From patchwork Tue Jan 14 03:51:10 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Kicinski X-Patchwork-Id: 13938385 X-Patchwork-Delegate: kuba@kernel.org 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 677CE23353C for ; Tue, 14 Jan 2025 03:51:33 +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=1736826693; cv=none; b=ApUtL1scGXJfNgXFce78eBqzOw4bKYeu9TsgEjPfVNslu89AwGIH60vWmKnyzdsQ8D7tw/UCDI2gzGUvHi0b80r77HHbweQHuzQI9QpTZcpp1aGo1QWpWrkQsE7nt6BIh8sX0swOTJpe+0T0PQOOSuIu+8wb9IimSL+e92COUXw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736826693; c=relaxed/simple; bh=o9GEh7JWbKmRqO6sblRDoE/qu3xXdfDzYkpbWQC0itI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lYFLG03MbZiNCUiApEgimH2ebqR9Dt0FmCg/4ehB5+RVd4sf8e8DFJo752U6JW+YpHO3Flf5j8LgNClBm6vb5iWPYGvVOZuGNPgqJHsef2VqtncLAqRnvrhk9L7mj3OFz8x/5HRo2PJ4w1SktF1ce6HJdzG1KhjnZB0b6BtyNdQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uNmC0tSu; 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="uNmC0tSu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66459C4CEE1; Tue, 14 Jan 2025 03:51:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736826692; bh=o9GEh7JWbKmRqO6sblRDoE/qu3xXdfDzYkpbWQC0itI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uNmC0tSugOSFYtTJkdGCHTsj2CKV5Y11g+FjE7q31w6a2z1oB82/yu+T9AbQZaTKd h7Wp2OdH6jeYdKF4TMAaxZStUfi1To5R8MU1hnn/QBpNHF+9nQA1NeoUuLMwA/9gMO Ej0cLRAyoc8jvD4hFf1ze5CEfo1OGH4juOGt03/b4z1rvBNfM+YCd8Er5izD2PnEXF cLMfOlNdOi04tPZaXbnZIp4SpU8GdxKy/+uoFzgSwQn7sKIxVIcrVwIZ0gG78Mevz7 WqiOUalYpLGWgpy9aMoEyjlQNGemC5Jn/y3LMP0UWXzq+0MVrOtL1X2UHamOqWFzL2 6NTleg1v0mUhQ== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, jdamato@fastly.com, Jakub Kicinski Subject: [PATCH net-next 04/11] net: add netdev->up protected by netdev_lock() Date: Mon, 13 Jan 2025 19:51:10 -0800 Message-ID: <20250114035118.110297-5-kuba@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250114035118.110297-1-kuba@kernel.org> References: <20250114035118.110297-1-kuba@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Some uAPI (netdev netlink) hide net_device's sub-objects while the interface is down to ensure uniform behavior across drivers. To remove the rtnl_lock dependency from those uAPIs we need a way to safely tell if the device is down or up. Add an indication of whether device is open or closed, protected by netdev->lock. The semantics are the same as IFF_UP, but taking netdev_lock around every write to ->flags would be a lot of code churn. We don't want to blanket the entire open / close path by netdev_lock, because it will prevent us from applying it to specific structures - core helpers won't be able to take that lock from any function called by the drivers on open/close paths. So the state of the flag is "pessimistic", as in it may report false negatives, but never false positives. Signed-off-by: Jakub Kicinski Reviewed-by: Eric Dumazet Reviewed-by: Joe Damato --- include/linux/netdevice.h | 13 ++++++++++++- net/core/dev.h | 12 ++++++++++++ net/core/dev.c | 4 ++-- 3 files changed, 26 insertions(+), 3 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index bdbc5849469c..565dfeb78774 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2443,12 +2443,23 @@ struct net_device { unsigned long gro_flush_timeout; u32 napi_defer_hard_irqs; + /** + * @up: copy of @state's IFF_UP, but safe to read with just @lock. + * May report false negatives while the device is being opened + * or closed (@lock does not protect .ndo_open, or .ndo_close). + */ + bool up; + /** * @lock: netdev-scope lock, protects a small selection of fields. * Should always be taken using netdev_lock() / netdev_unlock() helpers. * Drivers are free to use it for other protection. * - * Protects: @reg_state, @net_shaper_hierarchy. + * Protects: + * @net_shaper_hierarchy, @reg_state + * Partially protects (readers hold either @lock or rtnl_lock, + * writers must hold both for registered devices): + * @up * Ordering: take after rtnl_lock. */ struct mutex lock; diff --git a/net/core/dev.h b/net/core/dev.h index 25ae732c0775..ef37e2dd44f4 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -128,6 +128,18 @@ void __dev_notify_flags(struct net_device *dev, unsigned int old_flags, void unregister_netdevice_many_notify(struct list_head *head, u32 portid, const struct nlmsghdr *nlh); +static inline void netif_set_up(struct net_device *dev, bool value) +{ + if (value) + dev->flags |= IFF_UP; + else + dev->flags &= ~IFF_UP; + + netdev_lock(dev); + dev->up = value; + netdev_unlock(dev); +} + static inline void netif_set_gso_max_size(struct net_device *dev, unsigned int size) { diff --git a/net/core/dev.c b/net/core/dev.c index 2ded6eedb4cc..1a05ad60b89f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1618,7 +1618,7 @@ static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack) if (ret) clear_bit(__LINK_STATE_START, &dev->state); else { - dev->flags |= IFF_UP; + netif_set_up(dev, true); dev_set_rx_mode(dev); dev_activate(dev); add_device_randomness(dev->dev_addr, dev->addr_len); @@ -1697,7 +1697,7 @@ static void __dev_close_many(struct list_head *head) if (ops->ndo_stop) ops->ndo_stop(dev); - dev->flags &= ~IFF_UP; + netif_set_up(dev, false); netpoll_poll_enable(dev); } }