linux-kernel - [tip: locking/core] seqlock: Change do_io_accounting() to use scoped_seqlock

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Message-ID: <176104292009.2601451.1208802602283544481.tip-bot2@tip-bot2>
Date: Tue, 21 Oct 2025 10:35:20 -0000
From: "tip-bot2 for Oleg Nesterov" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Oleg Nesterov <oleg@...hat.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: locking/core] seqlock: Change do_io_accounting() to use
 scoped_seqlock_read()

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

Commit-ID:     795aab353d0650b2d04dc3aa2e22a51000cb2aaa
Gitweb:        https://git.kernel.org/tip/795aab353d0650b2d04dc3aa2e22a51000cb2aaa
Author:        Oleg Nesterov <oleg@...hat.com>
AuthorDate:    Wed, 08 Oct 2025 14:31:05 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 21 Oct 2025 12:31:57 +02:00

seqlock: Change do_io_accounting() to use scoped_seqlock_read()

To simplify the code and make it more readable.

[peterz: change to new interface]
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 fs/proc/base.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6299878..407b41c 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3043,21 +3043,14 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
 	if (whole) {
 		struct signal_struct *sig = task->signal;
 		struct task_struct *t;
-		unsigned int seq = 1;
-		unsigned long flags;
-
-		rcu_read_lock();
-		do {
-			seq++; /* 2 on the 1st/lockless path, otherwise odd */
-			flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
 
+		guard(rcu)();
+		scoped_seqlock_read (&sig->stats_lock, ss_lock_irqsave) {
 			acct = sig->ioac;
 			__for_each_thread(sig, t)
 				task_io_accounting_add(&acct, &t->ioac);
 
-		} while (need_seqretry(&sig->stats_lock, seq));
-		done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
-		rcu_read_unlock();
+		}
 	} else {
 		acct = task->ioac;
 	}