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Two tracing fixes:

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- Add mutex protection to ring_buffer_reset()
 
 - Fix deadlock in modify_ftrace_direct_multi()
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Merge tag 'trace-v5.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Two locking fixes:

   - Add mutex protection to ring_buffer_reset()

   - Fix deadlock in modify_ftrace_direct_multi()"

* tag 'trace-v5.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/direct: Fix lockup in modify_ftrace_direct_multi
  ring-buffer: Protect ring_buffer_reset() from reentrancy
This commit is contained in:
Linus Torvalds 2021-11-11 10:16:33 -08:00
parent f54ca91fe6 2e6e9058d1
commit 600b18f88f
2 changed files with 7 additions and 1 deletions
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3
kernel/trace/ftrace.c
View file

@ -5602,10 +5602,11 @@ int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
}
}
mutex_unlock(&ftrace_lock);
/* Removing the tmp_ops will add the updated direct callers to the functions */
unregister_ftrace_function(&tmp_ops);
mutex_unlock(&ftrace_lock);
out_direct:
mutex_unlock(&direct_mutex);
return err;

5
kernel/trace/ring_buffer.c
View file

@ -5228,6 +5228,9 @@ void ring_buffer_reset(struct trace_buffer *buffer)
struct ring_buffer_per_cpu *cpu_buffer;
int cpu;
/* prevent another thread from changing buffer sizes */
mutex_lock(&buffer->mutex);
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
@ -5246,6 +5249,8 @@ void ring_buffer_reset(struct trace_buffer *buffer)
atomic_dec(&cpu_buffer->record_disabled);
atomic_dec(&cpu_buffer->resize_disabled);
}
mutex_unlock(&buffer->mutex);
}
EXPORT_SYMBOL_GPL(ring_buffer_reset);