diff options
| author | Joel Fernandes (Google) <joel@joelfernandes.org> | 2018-08-02 19:34:07 -0700 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-08-03 09:38:39 -0400 |
| commit | da25a672cf0e2c143bffb40acb507a342e25b4f4 (patch) | |
| tree | 757e60958231e24d92f1c840e3e3a8ebe53d14fd /kernel/trace | |
| parent | 6bc6c77cfc6747292d5865d124cc31333b1b8536 (diff) | |
trace: Use rcu_dereference_raw for hooks from trace-event subsystem
Since we switched to using SRCU for tracepoints used in the idle path,
we can no longer use rcu_dereference_sched for dereferencing points in
trace-event hooks.
Since tracepoints can now use either SRCU or sched-RCU, just use
rcu_dereference_raw for traceevents just like we're doing when
dereferencing the tracepoint table.
This prevents an RCU warning reported by Masami:
[ 282.060593] WARNING: can't dereference registers at 00000000f3c7f62b
[ 282.063200] =============================
[ 282.064082] WARNING: suspicious RCU usage
[ 282.064963] 4.18.0-rc6+ #15 Tainted: G W
[ 282.066048] -----------------------------
[ 282.066923] /home/mhiramat/ksrc/linux/kernel/trace/trace_events.c:242
suspicious rcu_dereference_check() usage!
[ 282.068974]
[ 282.068974] other info that might help us debug this:
[ 282.068974]
[ 282.070770]
[ 282.070770] RCU used illegally from idle CPU!
[ 282.070770] rcu_scheduler_active = 2, debug_locks = 1
[ 282.072938] RCU used illegally from extended quiescent state!
[ 282.074183] no locks held by swapper/0/0.
[ 282.075071]
[ 282.075071] stack backtrace:
[ 282.076121] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W
[ 282.077782] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[ 282.079604] Call Trace:
[ 282.080212] <IRQ>
[ 282.080755] dump_stack+0x85/0xcb
[ 282.081523] trace_event_ignore_this_pid+0x66/0x70
[ 282.082541] trace_event_raw_event_preemptirq_template+0xa2/0xb0
[ 282.083774] ? interrupt_entry+0xc4/0xe0
[ 282.084665] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 282.085669] trace_hardirqs_off_caller+0x90/0xd0
[ 282.086597] trace_hardirqs_off_thunk+0x1a/0x1c
[ 282.087433] ? call_function_interrupt+0xa/0x20
[ 282.088201] interrupt_entry+0xc4/0xe0
[ 282.088848] ? call_function_interrupt+0xa/0x20
[ 282.089579] </IRQ>
[ 282.090029] ? native_safe_halt+0x2/0x10
[ 282.090695] ? default_idle+0x1f/0x160
[ 282.091330] ? default_idle_call+0x24/0x40
[ 282.091997] ? do_idle+0x210/0x250
[ 282.092658] ? cpu_startup_entry+0x6f/0x80
[ 282.093338] ? start_kernel+0x49d/0x4bd
[ 282.093987] ? secondary_startup_64+0xa5/0xb0
Link: http://lkml.kernel.org/r/20180803023407.225852-1-joel@joelfernandes.org
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: e6753f23d961 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_events.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 14ff4ff3caab..7b508ce8ac44 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -239,7 +239,7 @@ bool trace_event_ignore_this_pid(struct trace_event_file *trace_file) struct trace_array_cpu *data; struct trace_pid_list *pid_list; - pid_list = rcu_dereference_sched(tr->filtered_pids); + pid_list = rcu_dereference_raw(tr->filtered_pids); if (!pid_list) return false; @@ -512,7 +512,7 @@ event_filter_pid_sched_process_exit(void *data, struct task_struct *task) struct trace_pid_list *pid_list; struct trace_array *tr = data; - pid_list = rcu_dereference_sched(tr->filtered_pids); + pid_list = rcu_dereference_raw(tr->filtered_pids); trace_filter_add_remove_task(pid_list, NULL, task); } |