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authorKefeng Wang <wangkefeng.wang@huawei.com>2020-06-10 01:12:44 +0000
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2020-06-16 21:21:02 -0400
commite9b7b1c0c103a623be1a65c39f98719803440871 (patch)
tree33cc95e038fde369b2c6c3c3985d07985e8657b7 /samples/ftrace/sample-trace-array.c
parent9b38cc704e844e41d9cf74e647bff1d249512cb3 (diff)
sample-trace-array: Fix sleeping function called from invalid context
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: 89ed42495ef4 ("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>
Diffstat (limited to 'samples/ftrace/sample-trace-array.c')
-rw-r--r--samples/ftrace/sample-trace-array.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/samples/ftrace/sample-trace-array.c b/samples/ftrace/sample-trace-array.c
index d523450d73eb..9e437f930280 100644
--- a/samples/ftrace/sample-trace-array.c
+++ b/samples/ftrace/sample-trace-array.c
@@ -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