[PATCH v3 1/2] ftrace: disable preemption between ftrace_test_recursion_trylock/unlock()
rostedt at goodmis.org
Thu Oct 14 20:39:07 PDT 2021
On Thu, 14 Oct 2021 17:14:07 +0200
Petr Mladek <pmladek at suse.com> wrote:
> * ftrace_test_recursion_trylock - tests for recursion in same context
> * Use this for ftrace callbacks. This will detect if the function
> * tracing recursed in the same context (normal vs interrupt),
> * Returns: -1 if a recursion happened.
> - * >= 0 if no recursion
> + * >= 0 if no recursion (success)
> + *
> + * Disables the preemption on success. It is just for a convenience.
> + * Current users needed to disable the preemtion for some reasons.
I started replying to this explaining the difference between bit not
zero and a bit zero, and I think I found a design flaw that can allow
It's late and I'm about to go to bed, but I may have a new patch to fix
this before this gets added, as the fix will conflict with this patch,
and the fix will likely need to go to stable.
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