From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E510240FE5; Sun, 24 Nov 2024 13:53:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732456425; cv=none; b=X985C7ctovcpB96UK/QrslQsUA4OZOnsJBDn5j4aSU4bJOeg21udsLuY/qdvwiE7qRUTpCDDC0Y0kCqZONQOd6Ogn/XxaSqn3biHSFVy3M4f2QHOkhQbgipwnvY6Edm1TJwXif0zH9jGv09g0MSN2yYWUdWyodOy6+bqRQChITM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732456425; c=relaxed/simple; bh=pXZyNcESKO1/12y1rcyEuI8zYSSFEPtGF4s6DVtZrf4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I02u4Kb2b/YCkFZt+ofTzjyhwnqL4LmiNgpc+GIUfyTH3p8/RPDiLE1t+Xut2MlQiC1OHNcVtkM2qm9EpP8UAe84fVn/RRT91bCe5o37TdjiVqMhmyTsK/drGcipvD7nWbO8afnjdx4xpjmq5NgM1Y9hy2PDuDhHiG+0BCR664w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P/tEkjCC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P/tEkjCC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B534EC4CED1; Sun, 24 Nov 2024 13:53:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732456425; bh=pXZyNcESKO1/12y1rcyEuI8zYSSFEPtGF4s6DVtZrf4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P/tEkjCCgqoNAKQ/YQ2YM9GjHFPyh8bSc8JNdAhIU3MibCOJ4TgLPGo8t9tkSpl97 Yg7XDiMhpHv2dfzWVnI0Cxj+7rFJOfid3fIzI5bCmqI8yuTqBl5GOA7J9EL1aj7L8U I+xzWNtjKtkYpqmG6yMDSq6EM4qll2/skKoGSzBaYu1PsYwhucB9e01xkHikga02Xu u/B3hHtDs9ehMTWf8hHK7SN9Y3+5igKWI5zSTqfTNH+WscE3NvrqjI6qWNAynhSNu5 3dKQShgIDaUaF6jEDWNOQ8GImGm8Z6ADbZaeUEuGJ6pkoKIjbdW+v/ocwh3OXw2OOk OAApMui/ELW3w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Breno Leitao , Michal Kubiak , Jakub Kicinski , Sasha Levin , davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, viro@zeniv.linux.org.uk, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 36/36] netpoll: Use rcu_access_pointer() in __netpoll_setup Date: Sun, 24 Nov 2024 08:51:50 -0500 Message-ID: <20241124135219.3349183-36-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241124135219.3349183-1-sashal@kernel.org> References: <20241124135219.3349183-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.173 Content-Transfer-Encoding: 8bit From: Breno Leitao [ Upstream commit c69c5e10adb903ae2438d4f9c16eccf43d1fcbc1 ] The ndev->npinfo pointer in __netpoll_setup() is RCU-protected but is being accessed directly for a NULL check. While no RCU read lock is held in this context, we should still use proper RCU primitives for consistency and correctness. Replace the direct NULL check with rcu_access_pointer(), which is the appropriate primitive when only checking for NULL without dereferencing the pointer. This function provides the necessary ordering guarantees without requiring RCU read-side protection. Reviewed-by: Michal Kubiak Signed-off-by: Breno Leitao Link: https://patch.msgid.link/20241118-netpoll_rcu-v1-1-a1888dcb4a02@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/netpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 2a9d95368d5a2..597e83e2bce86 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -636,7 +636,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev) goto out; } - if (!ndev->npinfo) { + if (!rcu_access_pointer(ndev->npinfo)) { npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL); if (!npinfo) { err = -ENOMEM; -- 2.43.0