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authorSteven Rostedt <srostedt@redhat.com>2012-06-05 19:28:14 +0900
committerSteven Rostedt <rostedt@goodmis.org>2012-07-31 10:29:55 -0400
commit72ef3794c5cd5f5f0e6355c24a529224c449cd14 (patch)
tree3c8c4bb28009aa938c9e24b33914d11852ec4712 /kernel/kprobes.c
parent647664eaf4033501739ac1f42dd52ce8c9266ccc (diff)
downloadlwn-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.c4
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))