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kprobes: Remove unnecessary module_mutex locking from kprobe_optimizer()

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Since we already lock both kprobe_mutex and text_mutex in the optimizer,
text will not be changed and the module unloading will be stopped
inside kprobes_module_callback().

The mutex_lock() has originally been introduced to avoid conflict with text modification,
at that point we didn't hold text_mutex.

But after:

  f1c6ece23729 ("kprobes: Fix potential deadlock in kprobe_optimizer()")

We started holding the text_mutex and don't need the modules mutex anyway.

So remove the module_mutex locking.

[ mingo: Amended the changelog. ]

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Link: https://lore.kernel.org/r/20200728163400.e00b09c594763349f99ce6cb@kernel.org
This commit is contained in:
Masami Hiramatsu 2020-07-28 16:34:00 +09:00 committed by Ingo Molnar
parent e89d4ca1df
commit 112a0e4171
1 changed files with 0 additions and 3 deletions
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3
kernel/kprobes.c
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@ -598,8 +598,6 @@ static void kprobe_optimizer(struct work_struct *work)
mutex_lock(&kprobe_mutex);
cpus_read_lock();
mutex_lock(&text_mutex);
/* Lock modules while optimizing kprobes */
mutex_lock(&module_mutex);
/*
* Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
@ -624,7 +622,6 @@ static void kprobe_optimizer(struct work_struct *work)
/* Step 4: Free cleaned kprobes after quiesence period */
do_free_cleaned_kprobes();
mutex_unlock(&module_mutex);
mutex_unlock(&text_mutex);
cpus_read_unlock();