Messages in this thread Patch in this message | | | Subject | [PATCH][GIT PULL] tracing: Return -EBUSY when event_enable_func() fails to get module | From | Steven Rostedt <> | Date | Wed, 22 May 2013 15:08:45 -0400 |
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Linus,
Masami Hiramatsu fixed another bug. This time returning a proper result in event_enable_func(). After checking the return status of try_module_get(), it returned the status of try_module_get(). But try_module_get() returns 0 on failure, which is success for event_enable_func().
Please pull the latest trace-fixes-v3.10-rc2 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-fixes-v3.10-rc2
Tag SHA1: f1733dffe0252fd03bf115d6b15b0e0842b3facd Head SHA1: 6ed0106667d76589cb648c27edb4f4ffbf9d59ca
Masami Hiramatsu (1): tracing: Return -EBUSY when event_enable_func() fails to get module
---- kernel/trace/trace_events.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --------------------------- commit 6ed0106667d76589cb648c27edb4f4ffbf9d59ca Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Date: Thu May 16 20:48:49 2013 +0900
tracing: Return -EBUSY when event_enable_func() fails to get module Since try_module_get() returns false( = 0) when it fails to pindown a module, event_enable_func() returns 0 which means "succeed". This can cause a kernel panic when the entry is removed, because the event is already released. This fixes the bug by returning -EBUSY, because the reason why it fails is that the module is being removed at that time. Link: http://lkml.kernel.org/r/20130516114848.13508.97899.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 7a0cf68..27963e2 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2072,8 +2072,10 @@ event_enable_func(struct ftrace_hash *hash, out_reg: /* Don't let event modules unload while probe registered */ ret = try_module_get(file->event_call->mod); - if (!ret) + if (!ret) { + ret = -EBUSY; goto out_free; + } ret = __ftrace_event_enable_disable(file, 1, 1); if (ret < 0)
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