linux-kernel - [PATCH] cred: Fix RCU warnings in override/revert

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Message-ID: <Z8QGQGW0IaSklKG7@gondor.apana.org.au>
Date: Sun, 2 Mar 2025 15:18:24 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Christian Brauner <brauner@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Vinicius Costa Gomes <vinicius.gomes@...el.com>,
	Amir Goldstein <amir73il@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH] cred: Fix RCU warnings in override/revert_creds

Fix RCU warnings in override_creds and revert_creds by turning
the RCU pointer into a normal pointer using rcu_replace_pointer.

These warnings were previously private to the cred code, but due
to the move into the header file they are now polluting unrelated
subsystems.

Fixes: 49dffdfde462 ("cred: Add a light version of override/revert_creds()")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 0c3c4b16b469..5658a3bfe803 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -172,18 +172,12 @@ static inline bool cap_ambient_invariant_ok(const struct cred *cred)
 
 static inline const struct cred *override_creds(const struct cred *override_cred)
 {
-	const struct cred *old = current->cred;
-
-	rcu_assign_pointer(current->cred, override_cred);
-	return old;
+	return rcu_replace_pointer(current->cred, override_cred, 1);
 }
 
 static inline const struct cred *revert_creds(const struct cred *revert_cred)
 {
-	const struct cred *override_cred = current->cred;
-
-	rcu_assign_pointer(current->cred, revert_cred);
-	return override_cred;
+	return rcu_replace_pointer(current->cred, revert_cred, 1);
 }
 
 /**
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt