From: Steven Rostedt <rostedt@kernel.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 2/2] tracing: Use switch statement instead of ifs in set_tracer_flag()
Date: Wed, 05 Nov 2025 19:33:26 -0500 [thread overview]
Message-ID: <20251106003501.890298562@kernel.org> (raw)
In-Reply-To: 20251106003324.964761749@kernel.org
From: Steven Rostedt <rostedt@goodmis.org>
The "mask" passed in to set_trace_flag() has a single bit set. The
function then checks if the mask is equal to one of the option masks and
performs the appropriate function associated to that option.
Instead of having a bunch of "if ()" statement, use a "switch ()"
statement instead to make it cleaner and a bit more optimal.
No function changes.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 38 +++++++++++++++++++++++---------------
1 file changed, 23 insertions(+), 15 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 07bd10808277..8460bec9f263 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5251,11 +5251,13 @@ int trace_keep_overwrite(struct tracer *tracer, u64 mask, int set)
int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
{
- if ((mask == TRACE_ITER(RECORD_TGID)) ||
- (mask == TRACE_ITER(RECORD_CMD)) ||
- (mask == TRACE_ITER(TRACE_PRINTK)) ||
- (mask == TRACE_ITER(COPY_MARKER)))
+ switch (mask) {
+ case TRACE_ITER(RECORD_TGID):
+ case TRACE_ITER(RECORD_CMD):
+ case TRACE_ITER(TRACE_PRINTK):
+ case TRACE_ITER(COPY_MARKER):
lockdep_assert_held(&event_mutex);
+ }
/* do nothing if flag is already set */
if (!!(tr->trace_flags & mask) == !!enabled)
@@ -5266,7 +5268,8 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
if (tr->current_trace->flag_changed(tr, mask, !!enabled))
return -EINVAL;
- if (mask == TRACE_ITER(TRACE_PRINTK)) {
+ switch (mask) {
+ case TRACE_ITER(TRACE_PRINTK):
if (enabled) {
update_printk_trace(tr);
} else {
@@ -5283,9 +5286,9 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
if (printk_trace == tr)
update_printk_trace(&global_trace);
}
- }
+ break;
- if (mask == TRACE_ITER(COPY_MARKER)) {
+ case TRACE_ITER(COPY_MARKER):
update_marker_trace(tr, enabled);
/* update_marker_trace updates the tr->trace_flags */
return 0;
@@ -5296,10 +5299,12 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
else
tr->trace_flags &= ~mask;
- if (mask == TRACE_ITER(RECORD_CMD))
+ switch (mask) {
+ case TRACE_ITER(RECORD_CMD):
trace_event_enable_cmd_record(enabled);
+ break;
- if (mask == TRACE_ITER(RECORD_TGID)) {
+ case TRACE_ITER(RECORD_TGID):
if (trace_alloc_tgid_map() < 0) {
tr->trace_flags &= ~TRACE_ITER(RECORD_TGID);
@@ -5307,24 +5312,27 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
}
trace_event_enable_tgid_record(enabled);
- }
+ break;
- if (mask == TRACE_ITER(EVENT_FORK))
+ case TRACE_ITER(EVENT_FORK):
trace_event_follow_fork(tr, enabled);
+ break;
- if (mask == TRACE_ITER(FUNC_FORK))
+ case TRACE_ITER(FUNC_FORK):
ftrace_pid_follow_fork(tr, enabled);
+ break;
- if (mask == TRACE_ITER(OVERWRITE)) {
+ case TRACE_ITER(OVERWRITE):
ring_buffer_change_overwrite(tr->array_buffer.buffer, enabled);
#ifdef CONFIG_TRACER_MAX_TRACE
ring_buffer_change_overwrite(tr->max_buffer.buffer, enabled);
#endif
- }
+ break;
- if (mask == TRACE_ITER(PRINTK)) {
+ case TRACE_ITER(PRINTK):
trace_printk_start_stop_comm(enabled);
trace_printk_control(enabled);
+ break;
}
return 0;
--
2.51.0
prev parent reply other threads:[~2025-11-06 0:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-06 0:33 [PATCH 0/2] tracing: Clean up of set_tracer_flag() Steven Rostedt
2025-11-06 0:33 ` [PATCH 1/2] tracing: Exit out immediately after update_marker_trace() Steven Rostedt
2025-11-06 0:33 ` Steven Rostedt [this message]
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