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Message-ID: <20241006060042.17613-1-quic_pintu@quicinc.com>
Date: Sun, 6 Oct 2024 11:30:42 +0530
From: Pintu Kumar <quic_pintu@...cinc.com>
To: <hannes@...xchg.org>, <surenb@...gle.com>, <peterz@...radead.org>,
<mingo@...hat.com>, <juri.lelli@...hat.com>,
<vincent.guittot@...aro.org>, <dietmar.eggemann@....com>,
<rostedt@...dmis.org>, <bsegall@...gle.com>, <mgorman@...e.de>,
<vschneid@...hat.com>, <christophe.jaillet@...adoo.fr>,
<linux-kernel@...r.kernel.org>
CC: <joe@...ches.com>, <skhan@...uxfoundation.org>, <pintu.ping@...il.com>,
Pintu Kumar <quic_pintu@...cinc.com>
Subject: [PATCH v4] sched/psi: fix memory barrier without comment warnings
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@...cinc.com>
---
Changes in V4:
Added () in comment as well suggested by Christophe JAILLET.
V3: https://lore.kernel.org/all/00aeb243-3d47-42be-b52c-08b39c5fef07@wanadoo.fr/
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..175423716e4c 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
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