block: show request_queue freeze status

When request_queue is freezed, processes which start issuing io will be
blocked, add two new field to blockinfo dump, "Freeze Depth" will tell
how many queue freezing operations is going on and "Usage Counter"
represents those operations who own one ref count of the queue,
queue freezed succeed only when this counter drops to 0, so none zero
"Freeze Depth" with none zero "Usage Counter" means queue freezeing
operation is blocked by the "Usage Counter", the most common reason
for this is that there is in flight ios, check "Inflight I/Os" field.

Orabug: 37361260

Signed-off-by: Junxiao Bi <[email protected]>

drgn_tools/block.py

@@ -26,6 +26,7 @@
 from drgn_tools.corelens import CorelensModule
 from drgn_tools.table import print_table
 from drgn_tools.util import has_member
+from drgn_tools.util import percpu_ref_sum
 from drgn_tools.util import timestamp_str
 from drgn_tools.util import type_exists
 
@@ -631,18 +632,51 @@ def get_inflight_io_nr(prog: drgn.Program, disk: Object) -> int:
     return int(nr)
 
 
+def queue_freezed_depth(q: Object) -> int:
+    depth = q.mq_freeze_depth
+    if depth.type_.kind == TypeKind.INT:
+        return int(depth)
+    else:
+        return int(depth.counter)
+
+
+def queue_usage_counter(q: Object) -> int:
+    return percpu_ref_sum(q.prog_, q.q_usage_counter)
+
+
 def print_block_devs_info(prog: drgn.Program) -> None:
     """
     Prints the block device information
     """
-    output = [["MAJOR", "GENDISK", "NAME", "REQUEST_QUEUE", "Inflight I/Os"]]
+    output = [
+        [
+            "MAJOR",
+            "GENDISK",
+            "NAME",
+            "REQUEST_QUEUE",
+            "Inflight I/Os",
+            "Freezed Depth",
+            "Usage Counter",
+        ]
+    ]
     for disk in for_each_disk(prog):
+        q = disk.queue
         major = int(disk.major)
         gendisk = hex(disk.value_())
         name = disk.disk_name.string_().decode("utf-8")
-        rq = hex(disk.queue.value_())
+        rq = hex(q.value_())
         ios = get_inflight_io_nr(prog, disk)
-        output.append([str(major), gendisk, name, rq, str(ios)])
+        output.append(
+            [
+                str(major),
+                gendisk,
+                name,
+                rq,
+                str(ios),
+                str(queue_freezed_depth(q)),
+                str(queue_usage_counter(q)),
+            ]
+        )
     print_table(output)
 
 

drgn_tools/util.py

@@ -208,11 +208,11 @@ def percpu_ref_sum(prog: Program, ref: Object) -> int:
     PERCPU_COUNT_BIAS = 1 << (bits_per_long - 1)
     counter = atomic_count.counter & ~PERCPU_COUNT_BIAS
     if ptr & 0x3 != 0 or ptr == 0:
-        return counter
+        return int(counter)
     percpu = Object(prog, "unsigned long", address=ptr)
     for cpu in for_each_possible_cpu(prog):
         counter += per_cpu(percpu, cpu).value_()
-    return counter
+    return int(counter)
 
 
 def to_binary_units(num: t.Union[float, int], units: t.List[str]) -> str: