tracing fixes for v7.0:

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- Fix potential deadlock in osnoise and hotplug
 
   The interface_lock can be called by a osnoise thread and the CPU shutdown
   logic of osnoise can wait for this thread to finish. But cpus_read_lock()
   can also be taken while holding the interface_lock. This produces a
   circular lock dependency and can cause a deadlock.
 
   Swap the ordering of cpus_read_lock() and the interface_lock to have
   interface_lock taken within the cpus_read_lock() context to prevent this
   circular dependency.
 
 - Fix freeing of event triggers in early boot up
 
   If the same trigger is added on the kernel command line, the second
   one will fail to be applied and the trigger created will be freed.
   This calls into the deferred logic and creates a kernel thread to do
   the freeing. But the command line logic is called before kernel
   threads can be created and this leads to a NULL pointer dereference.
 
   Delay freeing event triggers until late init.
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Merge tag 'trace-v7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix potential deadlock in osnoise and hotplug

   The interface_lock can be called by a osnoise thread and the CPU
   shutdown logic of osnoise can wait for this thread to finish. But
   cpus_read_lock() can also be taken while holding the interface_lock.
   This produces a circular lock dependency and can cause a deadlock.

   Swap the ordering of cpus_read_lock() and the interface_lock to have
   interface_lock taken within the cpus_read_lock() context to prevent
   this circular dependency.

 - Fix freeing of event triggers in early boot up

   If the same trigger is added on the kernel command line, the second
   one will fail to be applied and the trigger created will be freed.
   This calls into the deferred logic and creates a kernel thread to do
   the freeing. But the command line logic is called before kernel
   threads can be created and this leads to a NULL pointer dereference.

   Delay freeing event triggers until late init.

* tag 'trace-v7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Drain deferred trigger frees if kthread creation fails
  tracing: Fix potential deadlock in cpu hotplug with osnoise

...

This commit is contained in:

Linus Torvalds 2026-03-28 09:59:09 -07:00

parent e522b75c44 250ab25391

commit cbfffcca2b

2 changed files with 71 additions and 18 deletions

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85

kernel/trace/trace_events_trigger.c

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10

kernel/trace/trace_osnoise.c

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