Optimize strspn. #603

V0idk · 2018-10-02T17:51:52Z

Variable count is redundant.

KernelPRBot · 2018-10-02T17:54:37Z

Thanks for your contribution to the Linux kernel!

Linux kernel development happens on mailing lists, rather than on GitHub - this GitHub repository is a read-only mirror that isn't used for accepting contributions. So that your change can become part of Linux, please email it to us as a patch.

Sending patches isn't quite as simple as sending a pull request, but fortunately it is a well documented process.

Here's what to do:

Format your contribution according to kernel requirements
Decide who to send your contribution to
Set up your system to send your contribution as an email
Send your contribution and wait for feedback

How do I format my contribution?

The Linux kernel community is notoriously picky about how contributions are formatted and sent. Fortunately, they have documented their expectations.

Firstly, all contributions need to be formatted as patches. A patch is a plain text document showing the change you want to make to the code, and documenting why it is a good idea.

You can create patches with git format-patch.

Secondly, patches need 'commit messages', which is the human-friendly documentation explaining what the change is and why it's necessary.

Thirdly, changes have some technical requirements. There is a Linux kernel coding style, and there are licensing requirements you need to comply with.

Both of these are documented in the Submitting Patches documentation that is part of the kernel.

Note that you will almost certainly have to modify your existing git commits to satisfy these requirements. Don't worry: there are many guides on the internet for doing this.

Who do I send my contribution to?

The Linux kernel is composed of a number of subsystems. These subsystems are maintained by different people, and have different mailing lists where they discuss proposed changes.

If you don't already know what subsystem your change belongs to, the get_maintainer.pl script in the kernel source can help you.

get_maintainer.pl will take the patch or patches you created in the previous step, and tell you who is responsible for them, and what mailing lists are used. You can also take a look at the MAINTAINERS file by hand.

Make sure that your list of recipients includes a mailing list. If you can't find a more specific mailing list, then LKML - the Linux Kernel Mailing List - is the place to send your patches.

It's not usually necessary to subscribe to the mailing list before you send the patches, but if you're interested in kernel development, subscribing to a subsystem mailing list is a good idea. (At this point, you probably don't need to subscribe to LKML - it is a very high traffic list with about a thousand messages per day, which is often not useful for beginners.)

How do I send my contribution?

Use git send-email, which will ensure that your patches are formatted in the standard manner. In order to use git send-email, you'll need to configure git to use your SMTP email server.

For more information about using git send-email, look at the Git documentation or type git help send-email. There are a number of useful guides and tutorials about git send-email that can be found on the internet.

How do I get help if I'm stuck?

Firstly, don't get discouraged! There are an enormous number of resources on the internet, and many kernel developers who would like to see you succeed.

Many issues - especially about how to use certain tools - can be resolved by using your favourite internet search engine.

If you can't find an answer, there are a few places you can turn:

Kernel Newbies - this website contains a lot of useful resources for new kernel developers.
The kernel documentation - see also the Documentation directory in the kernel tree.

If you get really, really stuck, you could try the owners of this bot, @daxtens and @ajdlinux. Please be aware that we do have full-time jobs, so we are almost certainly the slowest way to get answers!

I sent my patch - now what?

You wait.

You can check that your email has been received by checking the mailing list archives for the mailing list you sent your patch to. Messages may not be received instantly, so be patient. Kernel developers are generally very busy people, so it may take a few weeks before your patch is looked at.

Then, you keep waiting. Three things may happen:

You might get a response to your email. Often these will be comments, which may require you to make changes to your patch, or explain why your way is the best way. You should respond to these comments, and you may need to submit another revision of your patch to address the issues raised.
Your patch might be merged into the subsystem tree. Code that becomes part of Linux isn't merged into the main repository straight away - it first goes into the subsystem tree, which is managed by the subsystem maintainer. It is then batched up with a number of other changes sent to Linus for inclusion. (This process is described in some detail in the kernel development process guide).
Your patch might be ignored completely. This happens sometimes - don't take it personally. Here's what to do:
- Wait a bit more - patches often take several weeks to get a response; more if they were sent at a busy time.
- Kernel developers often silently ignore patches that break the rules. Check for obvious violations of the Submitting Patches guidelines, the style guidelines, and any other documentation you can find about your subsystem. Check that you're sending your patch to the right place.
- Try again later. When you resend it, don't add angry commentary, as that will get your patch ignored. It might also get you silently blacklisted.

Further information

Working with the kernel development community - the official documentation for new kernel contributors

Happy hacking!

This message was posted by a bot - if you have any questions or suggestions, please talk to my owners, @ajdlinux and @daxtens, or raise an issue at https://github.com/ajdlinux/KernelPRBot.

lieuwex · 2018-10-04T16:27:01Z

lib/string.c


 	for (p = s; *p != '\0'; ++p) {
 		for (a = accept; *a != '\0'; ++a) {
 			if (*p == *a)
 				break;
 		}
 		if (*a == '\0')
-			return count;
-		++count;
+			p - s;


shouldn't this be return p-s;

...my falut

While running the linux-nex with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <[email protected]> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Signed-off-by: Suzuki K Poulose <[email protected]> Signed-off-by: Mathieu Poirier <[email protected]> Cc: stable <[email protected]> # 5.1+

While running the linux-nex with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <[email protected]> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Signed-off-by: Suzuki K Poulose <[email protected]> Signed-off-by: Mathieu Poirier <[email protected]>

While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <[email protected]> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Signed-off-by: Suzuki K Poulose <[email protected]> [Fixed a typograhic error in the changelog] Signed-off-by: Mathieu Poirier <[email protected]>

While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <[email protected]> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Cc: stable <[email protected]> Signed-off-by: Suzuki K Poulose <[email protected]> [Fixed a typograhic error in the changelog] Signed-off-by: Mathieu Poirier <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 5511c0c upstream. While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <[email protected]> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Cc: stable <[email protected]> Signed-off-by: Suzuki K Poulose <[email protected]> [Fixed a typograhic error in the changelog] Signed-off-by: Mathieu Poirier <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>

Fixes checkpatch issues: CHECK: Alignment should match open parenthesis torvalds#87: FILE: drivers/reset/core.c:87: +static int of_reset_simple_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) CHECK: Lines should not end with a '(' torvalds#540: FILE: drivers/reset/core.c:540: +static struct reset_control *__reset_control_get_internal( CHECK: Alignment should match open parenthesis torvalds#603: FILE: drivers/reset/core.c:603: +struct reset_control *__of_reset_control_get(struct device_node *node, + const char *id, int index, bool shared, CHECK: Alignment should match open parenthesis torvalds#781: FILE: drivers/reset/core.c:781: +struct reset_control *__devm_reset_control_get(struct device *dev, + const char *id, int index, bool shared, Signed-off-by: Philipp Zabel <[email protected]>

rust: file: Add flags() method to `File`

PD#150465: driver defect clean up: torvalds#71 torvalds#77 torvalds#109 torvalds#127 torvalds#411 torvalds#600 torvalds#602 torvalds#603 torvalds#604 torvalds#611 torvalds#612 Change-Id: I38ac5ed6583bd6e57df9f42eaab04d05ee4ed663 Signed-off-by: Evoke Zhang <[email protected]>

According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <[email protected]>

According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <[email protected]> Reviewed-by: Ido Schimmel <[email protected]> Signed-off-by: David S. Miller <[email protected]>

[ Upstream commit 6ca3c00 ] According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <[email protected]> Reviewed-by: Ido Schimmel <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Sasha Levin <[email protected]>

[ Upstream commit 6ca3c00 ] According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <[email protected]> Reviewed-by: Ido Schimmel <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Ulrich Hecht <[email protected]>

BugLink: https://bugs.launchpad.net/bugs/2034469 [ Upstream commit 6ca3c00 ] According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <[email protected]> Reviewed-by: Ido Schimmel <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Kamal Mostafa <[email protected]> Signed-off-by: Stefan Bader <[email protected]>

With driver_async_probe=* on kernel command line, the following trace is produced because on i.MX8M Plus hardware because the soc-imx8m.c driver calls of_clk_get_by_name() which returns -EPROBE_DEFER because the clock driver is not yet probed. This was not detected during regular testing without driver_async_probe. Attempt to fix it by probing the SoC driver late, but I don't think that is the correct approach here. " ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at drivers/soc/imx/soc-imx8m.c:115 imx8mm_soc_revision+0xdc/0x180 CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-next-20240924-00002-g2062bb554dea torvalds#603 Hardware name: DH electronics i.MX8M Plus DHCOM Premium Developer Kit (3) (DT) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : imx8mm_soc_revision+0xdc/0x180 lr : imx8mm_soc_revision+0xd0/0x180 sp : ffff8000821fbcc0 x29: ffff8000821fbce0 x28: 0000000000000000 x27: ffff800081810120 x26: ffff8000818a9970 x25: 0000000000000006 x24: 0000000000824311 x23: ffff8000817f42c8 x22: ffff0000df8be210 x21: fffffffffffffdfb x20: ffff800082780000 x19: 0000000000000001 x18: ffffffffffffffff x17: ffff800081fff418 x16: ffff8000823e1000 x15: ffff0000c03b65e8 x14: ffff0000c00051b0 x13: ffff800082790000 x12: 0000000000000801 x11: ffff80008278ffff x10: ffff80008209d3a6 x9 : ffff80008062e95c x8 : ffff8000821fb9a0 x7 : 0000000000000000 x6 : 00000000000080e3 x5 : ffff0000df8c03d8 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : fffffffffffffdfb x0 : fffffffffffffdfb Call trace: imx8mm_soc_revision+0xdc/0x180 imx8_soc_init+0xb0/0x1e0 do_one_initcall+0x94/0x1a8 kernel_init_freeable+0x240/0x2a8 kernel_init+0x28/0x140 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- SoC: i.MX8MP revision 1.1 " Signed-off-by: Marek Vasut <[email protected]>

With driver_async_probe=* on kernel command line, the following trace is produced because on i.MX8M Plus hardware because the soc-imx8m.c driver calls of_clk_get_by_name() which returns -EPROBE_DEFER because the clock driver is not yet probed. This was not detected during regular testing without driver_async_probe. Convert the SoC code to platform driver and instantiate a platform device in its current device_initcall() to probe the platform driver. Rework .soc_revision callback to always return valid error code and return SoC revision via parameter. This way, if anything in the .soc_revision callback return -EPROBE_DEFER, it gets propagated to .probe and the .probe will get retried later. " ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at drivers/soc/imx/soc-imx8m.c:115 imx8mm_soc_revision+0xdc/0x180 CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-next-20240924-00002-g2062bb554dea torvalds#603 Hardware name: DH electronics i.MX8M Plus DHCOM Premium Developer Kit (3) (DT) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : imx8mm_soc_revision+0xdc/0x180 lr : imx8mm_soc_revision+0xd0/0x180 sp : ffff8000821fbcc0 x29: ffff8000821fbce0 x28: 0000000000000000 x27: ffff800081810120 x26: ffff8000818a9970 x25: 0000000000000006 x24: 0000000000824311 x23: ffff8000817f42c8 x22: ffff0000df8be210 x21: fffffffffffffdfb x20: ffff800082780000 x19: 0000000000000001 x18: ffffffffffffffff x17: ffff800081fff418 x16: ffff8000823e1000 x15: ffff0000c03b65e8 x14: ffff0000c00051b0 x13: ffff800082790000 x12: 0000000000000801 x11: ffff80008278ffff x10: ffff80008209d3a6 x9 : ffff80008062e95c x8 : ffff8000821fb9a0 x7 : 0000000000000000 x6 : 00000000000080e3 x5 : ffff0000df8c03d8 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : fffffffffffffdfb x0 : fffffffffffffdfb Call trace: imx8mm_soc_revision+0xdc/0x180 imx8_soc_init+0xb0/0x1e0 do_one_initcall+0x94/0x1a8 kernel_init_freeable+0x240/0x2a8 kernel_init+0x28/0x140 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- SoC: i.MX8MP revision 1.1 " Signed-off-by: Marek Vasut <[email protected]>

With driver_async_probe=* on kernel command line, the following trace is produced because on i.MX8M Plus hardware because the soc-imx8m.c driver calls of_clk_get_by_name() which returns -EPROBE_DEFER because the clock driver is not yet probed. This was not detected during regular testing without driver_async_probe. Convert the SoC code to platform driver and instantiate a platform device in its current device_initcall() to probe the platform driver. Rework .soc_revision callback to always return valid error code and return SoC revision via parameter. This way, if anything in the .soc_revision callback return -EPROBE_DEFER, it gets propagated to .probe and the .probe will get retried later. " ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at drivers/soc/imx/soc-imx8m.c:115 imx8mm_soc_revision+0xdc/0x180 CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-next-20240924-00002-g2062bb554dea torvalds#603 Hardware name: DH electronics i.MX8M Plus DHCOM Premium Developer Kit (3) (DT) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : imx8mm_soc_revision+0xdc/0x180 lr : imx8mm_soc_revision+0xd0/0x180 sp : ffff8000821fbcc0 x29: ffff8000821fbce0 x28: 0000000000000000 x27: ffff800081810120 x26: ffff8000818a9970 x25: 0000000000000006 x24: 0000000000824311 x23: ffff8000817f42c8 x22: ffff0000df8be210 x21: fffffffffffffdfb x20: ffff800082780000 x19: 0000000000000001 x18: ffffffffffffffff x17: ffff800081fff418 x16: ffff8000823e1000 x15: ffff0000c03b65e8 x14: ffff0000c00051b0 x13: ffff800082790000 x12: 0000000000000801 x11: ffff80008278ffff x10: ffff80008209d3a6 x9 : ffff80008062e95c x8 : ffff8000821fb9a0 x7 : 0000000000000000 x6 : 00000000000080e3 x5 : ffff0000df8c03d8 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : fffffffffffffdfb x0 : fffffffffffffdfb Call trace: imx8mm_soc_revision+0xdc/0x180 imx8_soc_init+0xb0/0x1e0 do_one_initcall+0x94/0x1a8 kernel_init_freeable+0x240/0x2a8 kernel_init+0x28/0x140 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- SoC: i.MX8MP revision 1.1 " Signed-off-by: Marek Vasut <[email protected]> Signed-off-by: Shawn Guo <[email protected]>

Optimize strspn.

39cdcbc

Variable count is redundant.

lieuwex reviewed Oct 4, 2018

View reviewed changes

Update string.c

e2a3d75

danobi pushed a commit to danobi/linux that referenced this pull request Jan 9, 2022

Merge pull request torvalds#603 from danobi/file_flags

4f082c4

rust: file: Add flags() method to `File`

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Optimize strspn. #603

Optimize strspn. #603

V0idk commented Oct 2, 2018

KernelPRBot commented Oct 2, 2018

lieuwex Oct 4, 2018

V0idk Oct 4, 2018

Optimize strspn. #603

Are you sure you want to change the base?

Optimize strspn. #603

Conversation

V0idk commented Oct 2, 2018

KernelPRBot commented Oct 2, 2018

How do I format my contribution?

Who do I send my contribution to?

How do I send my contribution?

How do I get help if I'm stuck?

I sent my patch - now what?

Further information

lieuwex Oct 4, 2018

Choose a reason for hiding this comment

V0idk Oct 4, 2018

Choose a reason for hiding this comment