Fix cpu hotplug atomic sleep issue #12714
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Signed-off-by: Paul Dagnelie <[email protected]>
behlendorf
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Nov 2, 2021
ahrens
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Nov 2, 2021
tonynguien
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Nov 2, 2021
tonyhutter
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Mar 1, 2022
We move the spinlock unlock before the thread creation. This should be safe because the thread creation code doesn't actually manipulate any taskq data structures; that's done by the thread once it's created. We also remove the assertion that the maxthreads is the current threads plus one; that assertion could fail if multiple hotplug events come in quick succession, and the first new taskq thread hasn't had a chance to start processing yet. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matthew Ahrens <[email protected]> eviewed-by: Tony Nguyen <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes openzfs#12714
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Motivation and Context
See #12696
Description
We move the spinlock unlock before the thread creation. This should be safe because the thread creation code doesn't actually manipulate any taskq data structures; that's done by the thread once it's created. We also remove the assertion that the maxthreads is the current threads plus one; that assertion could fail if multiple hotplug events come in in quick succession, and the first new taskq thread hasn't had a chance to start processing yet.
How Has This Been Tested?
Manually tested CPU hotplug to verify stability, normal ZFS test suite. The patch has also been tested by people in the original issue, and it seems to have removed the BUG message.
Types of changes
Checklist:
Signed-off-by.