linux-kernel - [PATCH 4/5] seqlock: change do_io_accounting() to use SEQLOCK_READ

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Message-ID: <20251005145035.GA1263@redhat.com>
Date: Sun, 5 Oct 2025 16:50:35 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Alexander Viro <viro@...iv.linux.org.uk>,
	Boqun Feng <boqun.feng@...il.com>,
	David Howells <dhowells@...hat.com>, Ingo Molnar <mingo@...hat.com>,
	Li RongQing <lirongqing@...du.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Waiman Long <longman@...hat.com>, Will Deacon <will@...nel.org>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] seqlock: change do_io_accounting() to use
 SEQLOCK_READ_SECTION()

To simplify the code and make it more readable.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 fs/proc/base.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 62d35631ba8c..7ec507efbb99 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3041,20 +3041,15 @@ 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);
-
+		SEQLOCK_READ_SECTION(&sig->stats_lock, &flags) {
 			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;
-- 
2.25.1.362.g51ebf55