linux-kernel - [PATCH 01/11] smp: Disable preemption explicitly in __csd_lock

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Message-Id: <20260203112401.3889029-2-zhouchuyi@bytedance.com>
Date: Tue,  3 Feb 2026 19:23:51 +0800
From: "Chuyi Zhou" <zhouchuyi@...edance.com>
To: <tglx@...utronix.de>, <mingo@...hat.com>, <luto@...nel.org>, 
	<peterz@...radead.org>, <paulmck@...nel.org>, <muchun.song@...ux.dev>, 
	<bp@...en8.de>, <dave.hansen@...ux.intel.com>
Cc: <linux-kernel@...r.kernel.org>, "Chuyi Zhou" <zhouchuyi@...edance.com>
Subject: [PATCH 01/11] smp: Disable preemption explicitly in __csd_lock_wait

The latter patches will enable preemption before csd_lock_wait(), which
could break csdlock_debug. Because the slice of other tasks on the CPU may
be accounted between ktime_get_mono_fast_ns() calls. Disable preemption
explicitly in __csd_lock_wait(). This is a preparation for the next
patches.

Signed-off-by: Chuyi Zhou <zhouchuyi@...edance.com>
---
 kernel/smp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/smp.c b/kernel/smp.c
index f349960f79ca..fc1f7a964616 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -323,6 +323,8 @@ static void __csd_lock_wait(call_single_data_t *csd)
 	int bug_id = 0;
 	u64 ts0, ts1;
 
+	guard(preempt)();
+
 	ts1 = ts0 = ktime_get_mono_fast_ns();
 	for (;;) {
 		if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id, &nmessages))
-- 
2.20.1