linux-kernel - [tip: perf/core] uprobes: Remove redundant spinlock in uprobe_deny

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Message-ID: <173858689756.10177.14621017602283942308.tip-bot2@tip-bot2>
Date: Mon, 03 Feb 2025 12:48:17 -0000
From: "tip-bot2 for Liao Chang" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Liao Chang <liaochang1@...wei.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
 Oleg Nesterov <oleg@...hat.com>, x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: perf/core] uprobes: Remove redundant spinlock in uprobe_deny_signal()

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     eae8a56ae0c74c1cf2f92a6709d215a9f329f60c
Gitweb:        https://git.kernel.org/tip/eae8a56ae0c74c1cf2f92a6709d215a9f329f60c
Author:        Liao Chang <liaochang1@...wei.com>
AuthorDate:    Fri, 24 Jan 2025 09:38:25 
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 03 Feb 2025 11:46:06 +01:00

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.

Signed-off-by: Liao Chang <liaochang1@...wei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Acked-by: Oleg Nesterov <oleg@...hat.com>
Link: https://lore.kernel.org/r/20250124093826.2123675-2-liaochang1@huawei.com
---
 kernel/events/uprobes.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 2ca797c..33bd608 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -2302,9 +2302,7 @@ 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;