From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 1/5] tracing: Use __this_cpu_read() in trace_event_buffer_lock_reserver()
Date: Mon, 29 Nov 2021 21:39:46 -0500 [thread overview]
Message-ID: <20211130024318.698165354@goodmis.org> (raw)
In-Reply-To: 20211130023945.789683928@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
The value read by this_cpu_read() is used later and its use is expected to
stay on the same CPU as being read. But this_cpu_read() does not warn if
it is called without preemption disabled, where as __this_cpu_read() will
check if preemption is disabled on CONFIG_DEBUG_PREEMPT
Currently all callers have preemption disabled, but there may be new
callers in the future that may not.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4821fe6a40a5..2e87b7bf2ba7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2746,7 +2746,7 @@ trace_event_buffer_lock_reserve(struct trace_buffer **current_rb,
if (!tr->no_filter_buffering_ref &&
(trace_file->flags & (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
- (entry = this_cpu_read(trace_buffered_event))) {
+ (entry = __this_cpu_read(trace_buffered_event))) {
/*
* Filtering is on, so try to use the per cpu buffer first.
* This buffer will simulate a ring_buffer_event,
--
2.33.0
next prev parent reply other threads:[~2021-11-30 2:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 2:39 [PATCH 0/5] tracing: Various updates Steven Rostedt
2021-11-30 2:39 ` Steven Rostedt [this message]
2021-11-30 2:39 ` [PATCH 2/5] tracing: Disable preemption when using the filter buffer Steven Rostedt
2021-11-30 5:02 ` kernel test robot
2021-11-30 2:39 ` [PATCH 3/5] tracing: Have eprobes use filtering logic of trace events Steven Rostedt
2021-11-30 2:39 ` [PATCH 4/5] tracing/kprobes: Do not open code event reserve logic Steven Rostedt
2021-11-30 4:38 ` Masami Hiramatsu
2021-11-30 2:39 ` [PATCH 5/5] tracing/uprobes: Use trace_event_buffer_reserve() helper Steven Rostedt
2021-11-30 4:40 ` Masami Hiramatsu
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