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From: Pintu Kumar <quic_pintu@quicinc.com>
To: <hannes@cmpxchg.org>, <surenb@google.com>, <peterz@infradead.org>,
	<mingo@redhat.com>, <juri.lelli@redhat.com>,
	<vincent.guittot@linaro.org>, <dietmar.eggemann@arm.com>,
	<rostedt@goodmis.org>, <bsegall@google.com>, <mgorman@suse.de>,
	<vschneid@redhat.com>, <linux-kernel@vger.kernel.org>
Cc: <joe@perches.com>, <skhan@linuxfoundation.org>,
	<pintu.ping@gmail.com>, Pintu Kumar <quic_pintu@quicinc.com>
Subject: [PATCH v3] sched/psi: fix memory barrier without comment warnings
Date: Sat, 5 Oct 2024 23:15:35 +0530	[thread overview]
Message-ID: <20241005174535.2152-1-quic_pintu@quicinc.com> (raw)

These warnings were reported by checkpatch.
Fix them with minor changes.
No functional changes.

WARNING: memory barrier without comment
+       t = smp_load_acquire(trigger_ptr);

WARNING: memory barrier without comment
+       smp_store_release(&seq->private, new);

Signed-off-by: Pintu Kumar <quic_pintu@quicinc.com>

---
Changes in V3:
Removed signature of Joe as requested. No other change.
V2: https://lore.kernel.org/all/CAOuPNLi1mUKW_vv0E6Ynzvdw_rHvCye+nAf2bWv6Qj9A8ofX1g@mail.gmail.com/
Changes in V2:
Retain printk_deferred warnings as suggested by Joe Perches.
V1: https://lore.kernel.org/all/a848671f803ba2b4ab14b0f7b09f0f53a8dd1c4b.camel@perches.com/
---
 kernel/sched/psi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 020d58967d4e..4e4ff12fdeae 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1474,6 +1474,7 @@ __poll_t psi_trigger_poll(void **trigger_ptr,
 	if (static_branch_likely(&psi_disabled))
 		return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
 
+	/* Pairs with the smp_store_release in psi_write */
 	t = smp_load_acquire(trigger_ptr);
 	if (!t)
 		return DEFAULT_POLLMASK | EPOLLERR | EPOLLPRI;
@@ -1557,6 +1558,7 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf,
 		return PTR_ERR(new);
 	}
 
+	/* Pairs with the smp_store_acquire in psi_trigger_poll */
 	smp_store_release(&seq->private, new);
 	mutex_unlock(&seq->lock);
 
-- 
2.17.1


             reply	other threads:[~2024-10-05 17:46 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-05 17:45 Pintu Kumar [this message]
2024-10-05 18:52 ` Christophe JAILLET
2024-10-06  6:03   ` Pintu Agarwal

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