linux-kernel - [PATCH v4 03/13] perf: tracing: Simplify perf_sysenter

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Message-ID: <20251021005232.758121204@kernel.org>
Date: Mon, 20 Oct 2025 20:51:58 -0400
From: Steven Rostedt <rostedt@...nel.org>
To: linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Peter Zijlstra <peterz@...radead.org>,
 Namhyung Kim <namhyung@...nel.org>,
 Takaya Saeki <takayas@...gle.com>,
 Tom Zanussi <zanussi@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Ian Rogers <irogers@...gle.com>,
 Douglas Raillard <douglas.raillard@....com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Jiri Olsa <jolsa@...nel.org>,
 Adrian Hunter <adrian.hunter@...el.com>,
 Ingo Molnar <mingo@...hat.com>
Subject: [PATCH v4 03/13] perf: tracing: Simplify perf_sysenter_enable/disable() with guards

From: Steven Rostedt <rostedt@...dmis.org>

Use guard(mutex)(&syscall_trace_lock) for perf_sysenter_enable() and
perf_sysenter_disable() as well as for the perf_sysexit_enable() and
perf_sysexit_disable(). This will make it easier to update these functions
with other code that has early exit handling.

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v3: https://lore.kernel.org/20251015173548.540984239@kernel.org

- Fixed return value of perf_sysenter_enable() and perf_sysexit_enable()
  to not return undefined value (kernel test robot)

 kernel/trace/trace_syscalls.c | 48 ++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 98670006ebeb..de2b6e285fc5 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -1009,22 +1009,21 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 
 static int perf_sysenter_enable(struct trace_event_call *call)
 {
-	int ret = 0;
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
 
-	mutex_lock(&syscall_trace_lock);
-	if (!sys_perf_refcount_enter)
-		ret = register_trace_sys_enter(perf_syscall_enter, NULL);
-	if (ret) {
-		pr_info("event trace: Could not activate syscall entry trace point");
-	} else {
-		set_bit(num, enabled_perf_enter_syscalls);
-		sys_perf_refcount_enter++;
+	guard(mutex)(&syscall_trace_lock);
+	if (!sys_perf_refcount_enter) {
+		int ret = register_trace_sys_enter(perf_syscall_enter, NULL);
+		if (ret) {
+			pr_info("event trace: Could not activate syscall entry trace point");
+			return ret;
+		}
 	}
-	mutex_unlock(&syscall_trace_lock);
-	return ret;
+	set_bit(num, enabled_perf_enter_syscalls);
+	sys_perf_refcount_enter++;
+	return 0;
 }
 
 static void perf_sysenter_disable(struct trace_event_call *call)
@@ -1033,12 +1032,11 @@ static void perf_sysenter_disable(struct trace_event_call *call)
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
 
-	mutex_lock(&syscall_trace_lock);
+	guard(mutex)(&syscall_trace_lock);
 	sys_perf_refcount_enter--;
 	clear_bit(num, enabled_perf_enter_syscalls);
 	if (!sys_perf_refcount_enter)
 		unregister_trace_sys_enter(perf_syscall_enter, NULL);
-	mutex_unlock(&syscall_trace_lock);
 }
 
 static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *regs,
@@ -1115,22 +1113,21 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 
 static int perf_sysexit_enable(struct trace_event_call *call)
 {
-	int ret = 0;
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
 
-	mutex_lock(&syscall_trace_lock);
-	if (!sys_perf_refcount_exit)
-		ret = register_trace_sys_exit(perf_syscall_exit, NULL);
-	if (ret) {
-		pr_info("event trace: Could not activate syscall exit trace point");
-	} else {
-		set_bit(num, enabled_perf_exit_syscalls);
-		sys_perf_refcount_exit++;
+	guard(mutex)(&syscall_trace_lock);
+	if (!sys_perf_refcount_exit) {
+		int ret = register_trace_sys_exit(perf_syscall_exit, NULL);
+		if (ret) {
+			pr_info("event trace: Could not activate syscall exit trace point");
+			return ret;
+		}
 	}
-	mutex_unlock(&syscall_trace_lock);
-	return ret;
+	set_bit(num, enabled_perf_exit_syscalls);
+	sys_perf_refcount_exit++;
+	return 0;
 }
 
 static void perf_sysexit_disable(struct trace_event_call *call)
@@ -1139,12 +1136,11 @@ static void perf_sysexit_disable(struct trace_event_call *call)
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
 
-	mutex_lock(&syscall_trace_lock);
+	guard(mutex)(&syscall_trace_lock);
 	sys_perf_refcount_exit--;
 	clear_bit(num, enabled_perf_exit_syscalls);
 	if (!sys_perf_refcount_exit)
 		unregister_trace_sys_exit(perf_syscall_exit, NULL);
-	mutex_unlock(&syscall_trace_lock);
 }
 
 #endif /* CONFIG_PERF_EVENTS */
-- 
2.51.0