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 B262724BFD6; Sun, 24 Nov 2024 13:56:54 +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=1732456614; cv=none; b=cMXL3qxdLahDbvWgGc0NnMsaCCGRrCfP+uD5qDQ4KWJS9WBM7srlyqrgTjJruafe1AHO3HOnokQy4tLcZKOxpb45pt4FjznE8bRKstUtwGJCn2Xa6P7EbZ4pFkWsPXPYDiX8Qff8QqtFIbjr9C0ei3HWnkz5sHHSDt9PzoSdFaY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732456614; c=relaxed/simple; bh=+SavanS+peFDtun9ThuhSkPysREvObdvfpHagGM5VXQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NIb0sB/UhDQMkmQpGgyxzGmlqKq+l/vDX0BBakAuymlasOGWAy0coiQ0Eak+eihX4c9poAlzGOUsYCXCMJxv6CNcPyyM0DDcarjLUZ2I0EM/M+DZNNImKGjJb6KVtV6dlxaLF6pqEwFUOsFhJt7dbEOg/xs8vkb6mAmou3e/RBA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tbKMXSLm; 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="tbKMXSLm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 930D2C4CED6; Sun, 24 Nov 2024 13:56:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732456614; bh=+SavanS+peFDtun9ThuhSkPysREvObdvfpHagGM5VXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tbKMXSLmixiC/kRtAGgIpDpSMOLAs/Hn1wNIXD3h9ln/FzLIO3FPoKtix55p1J+Em AwjZZjOm1EKDhY+496Fbmfg0XwiemOio3E7QOh0gmO9I2+hA8cf/UCWk4cHMuXt9Zj v42A09yzo9zOjHY7j2eRlgdg2Fo+SX0ViL+6vX5PK7+P+Zcv9EgUUhWLjVUStJICRi RFKDgOf9vuwBgLyaGGVQVsfJ1OlEt8oqGo8GXPp9UWNBspbRKcR6ejXkoU+kp/rY9W Y+qFkV8ku7dAfFK3LQWYSKN9BDlk4vYXGAepA1jr7PBZ7MEzAPSjJRRGt6jJFQ0uK4 Cgoj2Ff4HiJmg== 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 5.4 28/28] netpoll: Use rcu_access_pointer() in __netpoll_setup Date: Sun, 24 Nov 2024 08:55:28 -0500 Message-ID: <20241124135549.3350700-28-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241124135549.3350700-1-sashal@kernel.org> References: <20241124135549.3350700-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.286 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 9b263a5c0f36f..9a67aa989d606 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -615,7 +615,7 @@ 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