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sample-trace-array: Fix sleeping function called from invalid context

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BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935
 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/5
 1 lock held by swapper/5/0:
  #0: ffff80001002bd90 (samples/ftrace/sample-trace-array.c:38){+.-.}-{0:0}, at: call_timer_fn+0x8/0x3e0
 CPU: 5 PID: 0 Comm: swapper/5 Not tainted 5.7.0+ #8
 Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
 Call trace:
  dump_backtrace+0x0/0x1a0
  show_stack+0x20/0x30
  dump_stack+0xe4/0x150
  ___might_sleep+0x160/0x200
  __might_sleep+0x58/0x90
  __mutex_lock+0x64/0x948
  mutex_lock_nested+0x3c/0x58
  __ftrace_set_clr_event+0x44/0x88
  trace_array_set_clr_event+0x24/0x38
  mytimer_handler+0x34/0x40 [sample_trace_array]

mutex_lock() will be called in interrupt context, using workqueue to fix it.

Link: https://lkml.kernel.org/r/20200610011244.2209486-1-wangkefeng.wang@huawei.com

Cc: stable@vger.kernel.org
Fixes: 89ed42495e ("tracing: Sample module to demonstrate kernel access to Ftrace instances.")
Reviewed-by: Divya Indi <divya.indi@oracle.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Kefeng Wang 2020-06-10 01:12:44 +00:00 committed by Steven Rostedt (VMware)
parent 9b38cc704e
commit e9b7b1c0c1
1 changed files with 13 additions and 5 deletions
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18
samples/ftrace/sample-trace-array.c
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@ -6,6 +6,7 @@
#include <linux/timer.h>
#include <linux/err.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
/*
* Any file that uses trace points, must include the header.
@ -20,6 +21,16 @@ struct trace_array *tr;
static void mytimer_handler(struct timer_list *unused);
static struct task_struct *simple_tsk;
static void trace_work_fn(struct work_struct *work)
{
/*
* Disable tracing for event "sample_event".
*/
trace_array_set_clr_event(tr, "sample-subsystem", "sample_event",
false);
}
static DECLARE_WORK(trace_work, trace_work_fn);
/*
* mytimer: Timer setup to disable tracing for event "sample_event". This
* timer is only for the purposes of the sample module to demonstrate access of
@ -29,11 +40,7 @@ static DEFINE_TIMER(mytimer, mytimer_handler);
static void mytimer_handler(struct timer_list *unused)
{
/*
* Disable tracing for event "sample_event".
*/
trace_array_set_clr_event(tr, "sample-subsystem", "sample_event",
false);
schedule_work(&trace_work);
}
static void simple_thread_func(int count)
@ -76,6 +83,7 @@ static int simple_thread(void *arg)
simple_thread_func(count++);
del_timer(&mytimer);
cancel_work_sync(&trace_work);
/*
* trace_array_put() decrements the reference counter associated with