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 1A9F037160; Fri, 1 Aug 2025 11:05:23 +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=1754046324; cv=none; b=Xe+RgUQcabDGLt+5p7S/ZCAS99aE1ERTmyUJhHIaX04iRRM0lS+o2yr3R5WzGcSLtJPkZlW1KayynEHJPiMsAfP+Fnt5bL6FeV8OArrx1bMdMZDoQqRVH/YcpMXEayJx6IpZLBYb+QNnAyWo0Vi0hskjmQ4F2vLK9UNiAZXTZtw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754046324; c=relaxed/simple; bh=difHokwBktTQLgVwGBkJrWHShhZQ9E1oVaauNa7VNeE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hVBB/jqeP+QBjKqUk5bv/zq4BLr690cSJfoeiSYYXo0/SWU6MgFpX5h8IBuVEAoz8u+39EqPZfRfuIkpBv2/ghut1jr4krbBfcSI3H2/dfE83HMxaNZNRLGzqL3ASAcCIoRHLBiCLC97vIXD3DxurQ8MsbYaEs8Yt4i86nV1/CA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jathTBlF; 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="jathTBlF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16632C4CEF4; Fri, 1 Aug 2025 11:05:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754046323; bh=difHokwBktTQLgVwGBkJrWHShhZQ9E1oVaauNa7VNeE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jathTBlF7iNB+Cbbbv7Bp8B6REodF3f8dw7fmOFIiC+dZs0hemDJzvRtNduOKaUle vTB1fiiDyKwLK+zVQk2HdErEi/cMItC5fvDRXoqxgeFVxWd0oW3EIIZe0dkT4elBV5 9eXfMv+4Xj5zum0UeONQ0DcgcEHNruLxbtq/TSHdt6TJ5Rxa2d/10JdiYPhazEWpUK REIULTqWqdNdmXZbo7SHopLECBdKFJ5tvp9k3GYSHaykwIFg+C+xdptN6jWK+1FNIM R8+3Jt8spyvo83SbsLV0ds+/+W7NDOsD9Cqk5P2juo5OeUguL2R52jKC2VOl1HDyt6 R+bHMMYu10i1Q== Date: Fri, 1 Aug 2025 12:05:18 +0100 From: Simon Horman To: Jijie Shao Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, andrew+netdev@lunn.ch, shenjian15@huawei.com, liuyonglong@huawei.com, chenhao418@huawei.com, jonathan.cameron@huawei.com, shameerali.kolothum.thodi@huawei.com, salil.mehta@huawei.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net 1/3] net: hibmcge: fix rtnl deadlock issue Message-ID: <20250801110518.GN8494@horms.kernel.org> References: <20250731134749.4090041-1-shaojijie@huawei.com> <20250731134749.4090041-2-shaojijie@huawei.com> <20250801100520.GJ8494@horms.kernel.org> <15388e7f-45a8-4356-88c9-45848c3a296f@huawei.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <15388e7f-45a8-4356-88c9-45848c3a296f@huawei.com> On Fri, Aug 01, 2025 at 06:44:36PM +0800, Jijie Shao wrote: > > on 2025/8/1 18:05, Simon Horman wrote: > > On Thu, Jul 31, 2025 at 09:47:47PM +0800, Jijie Shao wrote: > > > Currently, the hibmcge netdev acquires the rtnl_lock in > > > pci_error_handlers.reset_prepare() and releases it in > > > pci_error_handlers.reset_done(). > > > > > > However, in the PCI framework: > > > pci_reset_bus - __pci_reset_slot - pci_slot_save_and_disable_locked - > > > pci_dev_save_and_disable - err_handler->reset_prepare(dev); > > > > > > In pci_slot_save_and_disable_locked(): > > > list_for_each_entry(dev, &slot->bus->devices, bus_list) { > > > if (!dev->slot || dev->slot!= slot) > > > continue; > > > pci_dev_save_and_disable(dev); > > > if (dev->subordinate) > > > pci_bus_save_and_disable_locked(dev->subordinate); > > > } > > > > > > This will iterate through all devices under the current bus and execute > > > err_handler->reset_prepare(), causing two devices of the hibmcge driver > > > to sequentially request the rtnl_lock, leading to a deadlock. > > > > > > Since the driver now executes netif_device_detach() > > > before the reset process, it will not concurrently with > > > other netdev APIs, so there is no need to hold the rtnl_lock now. > > > > > > Therefore, this patch removes the rtnl_lock during the reset process and > > > adjusts the position of HBG_NIC_STATE_RESETTING to ensure > > > that multiple resets are not executed concurrently. > > > > > > Fixes: 3f5a61f6d504f ("net: hibmcge: Add reset supported in this module") > > > Signed-off-by: Jijie Shao > > > --- > > > drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c | 13 ++++--------- > > > 1 file changed, 4 insertions(+), 9 deletions(-) > > > > > > diff --git a/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c b/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c > > > index 503cfbfb4a8a..94bc6f0da912 100644 > > > --- a/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c > > > +++ b/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c > > > @@ -53,9 +53,11 @@ static int hbg_reset_prepare(struct hbg_priv *priv, enum hbg_reset_type type) > > > { > > > int ret; > > > - ASSERT_RTNL(); > > > + if (test_and_set_bit(HBG_NIC_STATE_RESETTING, &priv->state)) > > > + return -EBUSY; > > > if (netif_running(priv->netdev)) { > > > + clear_bit(HBG_NIC_STATE_RESETTING, &priv->state); > > > dev_warn(&priv->pdev->dev, > > > "failed to reset because port is up\n"); > > > return -EBUSY; > > > @@ -64,7 +66,6 @@ static int hbg_reset_prepare(struct hbg_priv *priv, enum hbg_reset_type type) > > > netif_device_detach(priv->netdev); > > > priv->reset_type = type; > > > - set_bit(HBG_NIC_STATE_RESETTING, &priv->state); > > > clear_bit(HBG_NIC_STATE_RESET_FAIL, &priv->state); > > > ret = hbg_hw_event_notify(priv, HBG_HW_EVENT_RESET); > > > if (ret) { > > > @@ -84,10 +85,8 @@ static int hbg_reset_done(struct hbg_priv *priv, enum hbg_reset_type type) > > > type != priv->reset_type) > > > return 0; > > > - ASSERT_RTNL(); > > > - > > > - clear_bit(HBG_NIC_STATE_RESETTING, &priv->state); > > > ret = hbg_rebuild(priv); > > > + clear_bit(HBG_NIC_STATE_RESETTING, &priv->state); > > Hi Jijie, > > > > If I understand things correctly, then with this patch the > > HBG_NIC_STATE_RESETTING bit is used to prevent concurrent execution. > > > > Noting that a reset may be triggered via eththool, where hbg_reset() is > > used as a callback, I am concerned about concurrency implications for lines > > below this one. > > Yes, just like the following, it can lead to reset and net open concurrency. > =========== > > reset1 reset2 open > > set_bit HBG_NIC_STATE_RESETTING > > netif_device_detach() > resetting... > > clear_bit HBG_NIC_STATE_RESETTING > set_bit HBG_NIC_STATE_RESETTING > netif_device_detach() > > netif_device_attach() > resetting... hbg_net_open() > hbg_txrx_init() > > clear_bit HBG_NIC_STATE_RESETTING > netif_device_attach() > > ============ > Thank you for your reminder. > I will fix it in V2 Likewise, thanks. -- pw-bot: cr