From: Zilin Guan <zilinguan811@gmail.com>
To: paulmck@kernel.org
Cc: frederic@kernel.org, neeraj.upadhyay@kernel.org,
joel@joelfernandes.org, josh@joshtriplett.org,
boqun.feng@gmail.com, urezki@gmail.com, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
qiang.zhang1211@gmail.com, rcu@vger.kernel.org,
linux-kernel@vger.kernel.org, Zilin Guan <zilinguan811@gmail.com>
Subject: [PATCH] rcu: Use READ_ONCE() for rdp->gpwrap access in __note_gp_changes()
Date: Mon, 4 Nov 2024 15:12:30 +0000 [thread overview]
Message-ID: <20241104151230.3107133-1-zilinguan811@gmail.com> (raw)
In function __note_gp_changes(), rdp->gpwrap is read using READ_ONCE()
in line 1307:
1307 if (IS_ENABLED(CONFIG_PROVE_RCU) && READ_ONCE(rdp->gpwrap))
1308 WRITE_ONCE(rdp->last_sched_clock, jiffies);
while read directly in line 1305:
1305 if (ULONG_CMP_LT(rdp->gp_seq_needed, rnp->gp_seq_needed) ||
rdp->gpwrap)
1306 WRITE_ONCE(rdp->gp_seq_needed, rnp->gp_seq_needed);
In the same environment, reads in two places should have the same
protection.
Signed-off-by: Zilin Guan <zilinguan811@gmail.com>
---
kernel/rcu/tree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b1f883fcd918..d3e2b420dce5 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1302,7 +1302,7 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp)
zero_cpu_stall_ticks(rdp);
}
rdp->gp_seq = rnp->gp_seq; /* Remember new grace-period state. */
- if (ULONG_CMP_LT(rdp->gp_seq_needed, rnp->gp_seq_needed) || rdp->gpwrap)
+ if (ULONG_CMP_LT(rdp->gp_seq_needed, rnp->gp_seq_needed) || READ_ONCE(rdp->gpwrap))
WRITE_ONCE(rdp->gp_seq_needed, rnp->gp_seq_needed);
if (IS_ENABLED(CONFIG_PROVE_RCU) && READ_ONCE(rdp->gpwrap))
WRITE_ONCE(rdp->last_sched_clock, jiffies);
--
2.34.1
next reply other threads:[~2024-11-04 15:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-04 15:12 Zilin Guan [this message]
2024-11-06 20:18 ` Paul E. McKenney
2024-11-07 14:01 ` Zilin Guan
2024-11-07 14:15 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20241104151230.3107133-1-zilinguan811@gmail.com \
--to=zilinguan811@gmail.com \
--cc=boqun.feng@gmail.com \
--cc=frederic@kernel.org \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=neeraj.upadhyay@kernel.org \
--cc=paulmck@kernel.org \
--cc=qiang.zhang1211@gmail.com \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=urezki@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®