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| author | Steven Rostedt <srostedt@redhat.com> | 2012-06-05 19:28:14 +0900 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2012-07-31 10:29:55 -0400 |
| commit | 72ef3794c5cd5f5f0e6355c24a529224c449cd14 (patch) | |
| tree | 3c8c4bb28009aa938c9e24b33914d11852ec4712 /kernel/kprobes.c | |
| parent | 647664eaf4033501739ac1f42dd52ce8c9266ccc (diff) | |
| download | lwn-72ef3794c5cd5f5f0e6355c24a529224c449cd14.tar.gz lwn-72ef3794c5cd5f5f0e6355c24a529224c449cd14.zip | |
kprobes: Inverse taking of module_mutex with kprobe_mutex
Currently module_mutex is taken before kprobe_mutex, but this
can cause issues when we have kprobes register ftrace, as the ftrace
mutex is taken before enabling a tracepoint, which currently takes
the module mutex.
If module_mutex is taken before kprobe_mutex, then we can not
have kprobes use the ftrace infrastructure.
There seems to be no reason that the kprobe_mutex can't be taken
before the module_mutex. Running lockdep shows that it is safe
among the kernels I've run.
Link: http://lkml.kernel.org/r/20120605102814.27845.21047.stgit@localhost.localdomain
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/kprobes.c')
| -rw-r--r-- | kernel/kprobes.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index c62b8546cc90..7a8a1222c7b1 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -561,9 +561,9 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) { LIST_HEAD(free_list); + mutex_lock(&kprobe_mutex); /* Lock modules while optimizing kprobes */ mutex_lock(&module_mutex); - mutex_lock(&kprobe_mutex); /* * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) @@ -586,8 +586,8 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) /* Step 4: Free cleaned kprobes after quiesence period */ do_free_cleaned_kprobes(&free_list); - mutex_unlock(&kprobe_mutex); mutex_unlock(&module_mutex); + mutex_unlock(&kprobe_mutex); /* Step 5: Kick optimizer again if needed */ if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) |