linux-kernel - [PATCH] ipmi: fix suspicious RCU usage warning

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Message-ID: <20250312131932.44d901f7@fangorn>
Date: Wed, 12 Mar 2025 13:19:32 -0400
From: Rik van Riel <riel@...riel.com>
To: Corey Minyard <corey@...yard.net>
Cc: "Paul E. McKenney" <paulmck@...nel.org>,
 openipmi-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
 kernel-team@...a.com
Subject: [PATCH] ipmi: fix suspicious RCU usage warning

On recent kernels this warning fires:

drivers/char/ipmi/ipmi_msghandler.c:1238 RCU-list traversed in non-reader section!!

This looks like a fairly simple lockdep trigger, where
list_for_each_entry_rcu and list_for_each_entry_srcu are
functionally identical, but the lockdep annotation in
the former has an extra check.

That extra check is whether the RCU read lock is held,
which is not true when the code uses srcu_read_lock.

Get rid of the warning by using the properly annotated
list traversal macro.

Signed-off-by: Rik van Riel <riel@...riel.com>
---
 drivers/char/ipmi/ipmi_msghandler.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 1e5313748f8b..a2823763fd37 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -1235,7 +1235,7 @@ int ipmi_create_user(unsigned int          if_num,
 		return -ENOMEM;

 	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+	list_for_each_entry_srcu(intf, &ipmi_interfaces, link) {
 		if (intf->intf_num == if_num)
 			goto found;
 	}
-- 
2.48.1