linux-kernel - [PATCH v3 1/2] uprobes: Remove redundant spinlock in uprobe_deny

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Message-ID: <20240815014629.2685155-2-liaochang1@huawei.com>
Date: Thu, 15 Aug 2024 01:46:28 +0000
From: Liao Chang <liaochang1@...wei.com>
To: <mhiramat@...nel.org>, <oleg@...hat.com>, <peterz@...radead.org>,
	<mingo@...hat.com>, <acme@...nel.org>, <namhyung@...nel.org>,
	<mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
	<jolsa@...nel.org>, <irogers@...gle.com>, <adrian.hunter@...el.com>,
	<kan.liang@...ux.intel.com>
CC: <linux-kernel@...r.kernel.org>, <linux-trace-kernel@...r.kernel.org>,
	<linux-perf-users@...r.kernel.org>, <bpf@...r.kernel.org>
Subject: [PATCH v3 1/2] uprobes: Remove redundant spinlock in uprobe_deny_signal()

Since clearing a bit in thread_info is an atomic operation, the spinlock
is redundant and can be removed, reducing lock contention is good for
performance.

Acked-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Liao Chang <liaochang1@...wei.com>
---
 kernel/events/uprobes.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 73cc47708679..76a51a1f51e2 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1979,9 +1979,7 @@ bool uprobe_deny_signal(void)
 	WARN_ON_ONCE(utask->state != UTASK_SSTEP);
 
 	if (task_sigpending(t)) {
-		spin_lock_irq(&t->sighand->siglock);
 		clear_tsk_thread_flag(t, TIF_SIGPENDING);
-		spin_unlock_irq(&t->sighand->siglock);
 
 		if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) {
 			utask->state = UTASK_SSTEP_TRAPPED;
-- 
2.34.1