From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>,
stable@vger.kernel.org, Vasily Averin <vvs@virtuozzo.com>
Subject: [for-linus][PATCH 08/12] tracing: Remove WARN_ON in start_thread()
Date: Tue, 01 Dec 2020 10:58:43 -0500 [thread overview]
Message-ID: <20201201160006.206022360@goodmis.org> (raw)
In-Reply-To: 20201201155835.647858317@goodmis.org
From: Vasily Averin <vvs@virtuozzo.com>
This patch reverts commit 978defee11a5 ("tracing: Do a WARN_ON()
if start_thread() in hwlat is called when thread exists")
.start hook can be legally called several times if according
tracer is stopped
screen window 1
[root@localhost ~]# echo 1 > /sys/kernel/tracing/events/kmem/kfree/enable
[root@localhost ~]# echo 1 > /sys/kernel/tracing/options/pause-on-trace
[root@localhost ~]# less -F /sys/kernel/tracing/trace
screen window 2
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo hwlat > /sys/kernel/debug/tracing/current_tracer
[root@localhost ~]# echo 1 > /sys/kernel/debug/tracing/tracing_on
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo 2 > /sys/kernel/debug/tracing/tracing_on
triggers warning in dmesg:
WARNING: CPU: 3 PID: 1403 at kernel/trace/trace_hwlat.c:371 hwlat_tracer_start+0xc9/0xd0
Link: https://lkml.kernel.org/r/bd4d3e70-400d-9c82-7b73-a2d695e86b58@virtuozzo.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 978defee11a5 ("tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_hwlat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index c9ad5c6fbaad..d071fc271eef 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -368,7 +368,7 @@ static int start_kthread(struct trace_array *tr)
struct task_struct *kthread;
int next_cpu;
- if (WARN_ON(hwlat_kthread))
+ if (hwlat_kthread)
return 0;
/* Just pick the first CPU on first iteration */
--
2.28.0
next prev parent reply other threads:[~2020-12-01 16:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 15:58 [for-linus][PATCH 00/12] tracing: Fixes for 5.10-rc6 Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 01/12] tools/bootconfig: Fix errno reference after printf() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 02/12] tools/bootconfig: Fix to check the write failure correctly Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 03/12] tools/bootconfig: Align the bootconfig applied initrd image size to 4 Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 04/12] docs: bootconfig: Update file format on initrd image Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 05/12] ring-buffer: Update write stamp with the correct ts Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 06/12] ring-buffer: Set the right timestamp in the slow path of __rb_reserve_next() Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 07/12] samples/ftrace: Mark my_tramp[12]? global Steven Rostedt
2020-12-01 15:58 ` Steven Rostedt [this message]
2020-12-01 15:58 ` [for-linus][PATCH 09/12] tracing: Fix alignment of static buffer Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 10/12] ftrace: Fix updating FTRACE_FL_TRAMP Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 11/12] ftrace: Fix DYNAMIC_FTRACE_WITH_DIRECT_CALLS dependency Steven Rostedt
2020-12-01 15:58 ` [for-linus][PATCH 12/12] ring-buffer: Always check to put back before stamp when crossing pages Steven Rostedt
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