* FAILED: patch "[PATCH] tracing/samples: Fix creation and deletion of" failed to apply to 4.9-stable tree
@ 2017-10-24 7:41 gregkh
2017-10-31 15:42 ` Steven Rostedt
0 siblings, 1 reply; 3+ messages in thread
From: gregkh @ 2017-10-24 7:41 UTC (permalink / raw)
To: rostedt; +Cc: stable
The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 6575257c60e1a26a5319ccf2b5ce5b6449001017 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Date: Tue, 17 Oct 2017 14:55:24 -0400
Subject: [PATCH] tracing/samples: Fix creation and deletion of
simple_thread_fn creation
Commit 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and
DEFINE_EVENT()") added template examples for all the events. It created a
DEFINE_EVENT_FN() example which reused the foo_bar_reg and foo_bar_unreg
functions.
Enabling both the TRACE_EVENT_FN() and DEFINE_EVENT_FN() example trace
events caused the foo_bar_reg to be called twice, creating the test thread
twice. The foo_bar_unreg would remove it only once, even if it was called
multiple times, leaving a thread existing when the module is unloaded,
causing an oops.
Add a ref count and allow foo_bar_reg() and foo_bar_unreg() be called by
multiple trace events.
Cc: stable@vger.kernel.org
Fixes: 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/samples/trace_events/trace-events-sample.c b/samples/trace_events/trace-events-sample.c
index bc7fcf010a5b..446beb7ac48d 100644
--- a/samples/trace_events/trace-events-sample.c
+++ b/samples/trace_events/trace-events-sample.c
@@ -78,29 +78,37 @@ static int simple_thread_fn(void *arg)
}
static DEFINE_MUTEX(thread_mutex);
+static bool simple_thread_cnt;
int foo_bar_reg(void)
{
+ mutex_lock(&thread_mutex);
+ if (simple_thread_cnt++)
+ goto out;
+
pr_info("Starting thread for foo_bar_fn\n");
/*
* We shouldn't be able to start a trace when the module is
* unloading (there's other locks to prevent that). But
* for consistency sake, we still take the thread_mutex.
*/
- mutex_lock(&thread_mutex);
simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
+ out:
mutex_unlock(&thread_mutex);
return 0;
}
void foo_bar_unreg(void)
{
- pr_info("Killing thread for foo_bar_fn\n");
- /* protect against module unloading */
mutex_lock(&thread_mutex);
+ if (--simple_thread_cnt)
+ goto out;
+
+ pr_info("Killing thread for foo_bar_fn\n");
if (simple_tsk_fn)
kthread_stop(simple_tsk_fn);
simple_tsk_fn = NULL;
+ out:
mutex_unlock(&thread_mutex);
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: FAILED: patch "[PATCH] tracing/samples: Fix creation and deletion of" failed to apply to 4.9-stable tree
2017-10-24 7:41 FAILED: patch "[PATCH] tracing/samples: Fix creation and deletion of" failed to apply to 4.9-stable tree gregkh
@ 2017-10-31 15:42 ` Steven Rostedt
2017-10-31 16:22 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: Steven Rostedt @ 2017-10-31 15:42 UTC (permalink / raw)
To: gregkh; +Cc: stable
Below is the fix. The only conflict between 4.9 and Linus's tree was
that foo_bar_reg() changed from a void to returning int.
Also, I folded in Linus's fix of having simple_thread_cnt be int and
not bool. You can remove that if you want to add Linus's commit on top.
I'm guessing this should also work for 4.4 as well?
-- Steve
------------------ original commit in Linus's tree ------------------
>>From 6575257c60e1a26a5319ccf2b5ce5b6449001017 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Date: Tue, 17 Oct 2017 14:55:24 -0400
Subject: [PATCH] tracing/samples: Fix creation and deletion of
simple_thread_fn creation
Commit 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and
DEFINE_EVENT()") added template examples for all the events. It created a
DEFINE_EVENT_FN() example which reused the foo_bar_reg and foo_bar_unreg
functions.
Enabling both the TRACE_EVENT_FN() and DEFINE_EVENT_FN() example trace
events caused the foo_bar_reg to be called twice, creating the test thread
twice. The foo_bar_unreg would remove it only once, even if it was called
multiple times, leaving a thread existing when the module is unloaded,
causing an oops.
Add a ref count and allow foo_bar_reg() and foo_bar_unreg() be called by
multiple trace events.
Cc: stable@vger.kernel.org
Fixes: 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Index: linux-trace.git/samples/trace_events/trace-events-sample.c
===================================================================
--- linux-trace.git.orig/samples/trace_events/trace-events-sample.c
+++ linux-trace.git/samples/trace_events/trace-events-sample.c
@@ -78,28 +78,36 @@ static int simple_thread_fn(void *arg)
}
static DEFINE_MUTEX(thread_mutex);
+static int simple_thread_cnt;
void foo_bar_reg(void)
{
+ mutex_lock(&thread_mutex);
+ if (simple_thread_cnt++)
+ goto out;
+
pr_info("Starting thread for foo_bar_fn\n");
/*
* We shouldn't be able to start a trace when the module is
* unloading (there's other locks to prevent that). But
* for consistency sake, we still take the thread_mutex.
*/
- mutex_lock(&thread_mutex);
simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
+ out:
mutex_unlock(&thread_mutex);
}
void foo_bar_unreg(void)
{
- pr_info("Killing thread for foo_bar_fn\n");
- /* protect against module unloading */
mutex_lock(&thread_mutex);
+ if (--simple_thread_cnt)
+ goto out;
+
+ pr_info("Killing thread for foo_bar_fn\n");
if (simple_tsk_fn)
kthread_stop(simple_tsk_fn);
simple_tsk_fn = NULL;
+ out:
mutex_unlock(&thread_mutex);
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: FAILED: patch "[PATCH] tracing/samples: Fix creation and deletion of" failed to apply to 4.9-stable tree
2017-10-31 15:42 ` Steven Rostedt
@ 2017-10-31 16:22 ` Greg KH
0 siblings, 0 replies; 3+ messages in thread
From: Greg KH @ 2017-10-31 16:22 UTC (permalink / raw)
To: Steven Rostedt; +Cc: stable
On Tue, Oct 31, 2017 at 11:42:36AM -0400, Steven Rostedt wrote:
>
> Below is the fix. The only conflict between 4.9 and Linus's tree was
> that foo_bar_reg() changed from a void to returning int.
>
> Also, I folded in Linus's fix of having simple_thread_cnt be int and
> not bool. You can remove that if you want to add Linus's commit on top.
I would rather add Linus's commit on top, thanks.
> I'm guessing this should also work for 4.4 as well?
I'll try it after this next round of kernels are released, thanks.
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-10-31 16:22 UTC | newest]
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2017-10-24 7:41 FAILED: patch "[PATCH] tracing/samples: Fix creation and deletion of" failed to apply to 4.9-stable tree gregkh
2017-10-31 15:42 ` Steven Rostedt
2017-10-31 16:22 ` Greg KH
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