diff options
| author | Nam Cao <namcao@linutronix.de> | 2025-06-26 17:19:40 +0200 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2025-07-22 20:15:51 -0400 |
| commit | c897c1e5b19dd4fc32e84fa1ab2065c2507be3a7 (patch) | |
| tree | d32e8ea7be22b8641a2df686243502c4adbddfed | |
| parent | 878e1e94a8aafb2f93a333a1aaed5e1c5f17e339 (diff) | |
tracing: Remove pointless memory barriers
Memory barriers are useful to ensure memory accesses from one CPU appear in
the original order as seen by other CPUs.
Some smp_rmb() and smp_wmb() are used, but they are not ordering multiple
memory accesses.
Remove them.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/20250626151940.1756398-1-namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/rv/rv.c | 6 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 7 |
2 files changed, 0 insertions, 13 deletions
diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c index e4077500a91d..c04a49da4328 100644 --- a/kernel/trace/rv/rv.c +++ b/kernel/trace/rv/rv.c @@ -675,8 +675,6 @@ static bool __read_mostly monitoring_on; */ bool rv_monitoring_on(void) { - /* Ensures that concurrent monitors read consistent monitoring_on */ - smp_rmb(); return READ_ONCE(monitoring_on); } @@ -696,8 +694,6 @@ static ssize_t monitoring_on_read_data(struct file *filp, char __user *user_buf, static void turn_monitoring_off(void) { WRITE_ONCE(monitoring_on, false); - /* Ensures that concurrent monitors read consistent monitoring_on */ - smp_wmb(); } static void reset_all_monitors(void) @@ -713,8 +709,6 @@ static void reset_all_monitors(void) static void turn_monitoring_on(void) { WRITE_ONCE(monitoring_on, true); - /* Ensures that concurrent monitors read consistent monitoring_on */ - smp_wmb(); } static void turn_monitoring_on_with_reset(void) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 95ae7c4e5835..0dff4298fc0e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -936,7 +936,6 @@ int tracing_is_enabled(void) * return the mirror variable of the state of the ring buffer. * It's a little racy, but we don't really care. */ - smp_rmb(); return !global_trace.buffer_disabled; } @@ -1107,8 +1106,6 @@ void tracer_tracing_on(struct trace_array *tr) * important to be fast than accurate. */ tr->buffer_disabled = 0; - /* Make the flag seen by readers */ - smp_wmb(); } /** @@ -1640,8 +1637,6 @@ void tracer_tracing_off(struct trace_array *tr) * important to be fast than accurate. */ tr->buffer_disabled = 1; - /* Make the flag seen by readers */ - smp_wmb(); } /** @@ -2710,8 +2705,6 @@ void trace_buffered_event_enable(void) static void enable_trace_buffered_event(void *data) { - /* Probably not needed, but do it anyway */ - smp_rmb(); this_cpu_dec(trace_buffered_event_cnt); } |