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 A743B1FCFD6; Sun, 24 Nov 2024 13:55:28 +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=1732456528; cv=none; b=UYuVHhWRMiWHdzoWrMp2Afx/a7VHaRZ4n1IYMH+pT3DaJ2V6+3MCWMKyGI3MpaeGZN1zDFQ2PIAV5GCkpSAxEMfmigf+yzxYoxkwz+cHGi3LMSzlLkOexUeaQsJ591mV6O9ZH0GU4DmhGnTqyAX1dGqJN5L9bNz6e/0aGtAI9eI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732456528; c=relaxed/simple; bh=u8EP5drxKPrzvzbBan3RsyQujzQo+A4/oHiSkOOsTJ4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nLH7b4ny4Lc6DkpoBcnkjM4411Xo4lKbvMK1WdtEB3pYCxv1wlLUfqI5dkI+nsssrw0mbitBax81NJzfZ4FgMhMmkk4rrC7JSf4mezCDwc3/8rxCbA2q+U7OWQpL5KUpFZnYP6uCfZWLgVYw8t/BtuzPWsrYWQwtpIywFwxWzu8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Y6M0ct6o; 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="Y6M0ct6o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC4A0C4CECC; Sun, 24 Nov 2024 13:55:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732456528; bh=u8EP5drxKPrzvzbBan3RsyQujzQo+A4/oHiSkOOsTJ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y6M0ct6opxELDO/mC3F2GhhNmt5LyrRyc0RJ+N6U3RkjsiiXrcyiRPtgqRcScoGU6 3f9+EWR5gvOt2fwKhWikYCJcTsDPmXSbfbocVHiNKTsFIjAMSYyRnyV+/ZRNXn/0uZ plMvSJA6lWLlsdc07lAXokb+jqxOt3TFnjXT5jGJ33Fv0HUtNhilofF2/joU8inATy J8M9HpTq5vrcRjlPm0vupRXUQoOQP14T/vuWen3gc3mL8HrVBqq0UXUTS+C8UHHvzI wNJIkRnKMjU5WaNDe23ud0cu1RzTpLKQL5+nbeHe0juuAZoSvrbc3HQUTKBHbjpyvl R5cqOtV61citQ== 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 5.10 33/33] netpoll: Use rcu_access_pointer() in __netpoll_setup Date: Sun, 24 Nov 2024 08:53:45 -0500 Message-ID: <20241124135410.3349976-33-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241124135410.3349976-1-sashal@kernel.org> References: <20241124135410.3349976-1-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 5.10.230 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 f76afab9fd8bd..4475b2174bcc4 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -635,7 +635,7 @@ 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