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 175505228; Sun, 12 Nov 2023 09:41:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="umeAOQNv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17725C433C7; Sun, 12 Nov 2023 09:41:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699782085; bh=QbWO5jczDTWfiCBuWGRjNrmWNSsp8db3vx0cMyEInsQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=umeAOQNvYTTSjOARLRDC8O83rwJGdTlNbnWGhFv+AtM1FcY6KDGpu0ebt34mXyMgs mzx0rO291VsLcpjMPdY/+qqpyqcHiwVs4driFi4ruXjHDBpqdNxdN5x8odw4LgZ9el fAov68D2HIVZOwkG774JqCWgLv+hs4uA90uvqXzRa/fP023WJEH1imsbh8e4KzmJ6L +AVidXc0e1g+uBfpun3DIuvUPzzxkHSHSmjdtn6AXbxcCD719eeFnIGQPofdh1WPE3 EIipNt01pq8UELRHjoKHEcBADsVRNSUSeM5S0Jy+TbrU3pKVX5K8BkYRXVenpiGCI7 yQivqWp6ApWqw== Date: Sun, 12 Nov 2023 09:41:15 +0000 From: Simon Horman To: Haiyang Zhang Cc: linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, kys@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net,v4, 2/3] hv_netvsc: Fix race of register_netdevice_notifier and VF register Message-ID: <20231112094115.GE705326@kernel.org> References: <1699627140-28003-1-git-send-email-haiyangz@microsoft.com> <1699627140-28003-3-git-send-email-haiyangz@microsoft.com> Precedence: bulk X-Mailing-List: linux-hyperv@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: <1699627140-28003-3-git-send-email-haiyangz@microsoft.com> On Fri, Nov 10, 2023 at 06:38:59AM -0800, Haiyang Zhang wrote: > If VF NIC is registered earlier, NETDEV_REGISTER event is replayed, > but NETDEV_POST_INIT is not. > > Move register_netdevice_notifier() earlier, so the call back > function is set before probing. > > Cc: stable@vger.kernel.org > Fixes: e04e7a7bbd4b ("hv_netvsc: Fix a deadlock by getting rtnl lock earlier in netvsc_probe()") > Reported-by: Dexuan Cui > Signed-off-by: Haiyang Zhang > Reviewed-by: Wojciech Drewek > > --- > v3: > Divide it into two patches, suggested by Jakub Kicinski. > v2: > Fix rtnl_unlock() in error handling as found by Wojciech Drewek. > --- > drivers/net/hyperv/netvsc_drv.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c > index 5e528a76f5f5..1d1491da303b 100644 > --- a/drivers/net/hyperv/netvsc_drv.c > +++ b/drivers/net/hyperv/netvsc_drv.c > @@ -2793,11 +2793,14 @@ static int __init netvsc_drv_init(void) > } > netvsc_ring_bytes = ring_size * PAGE_SIZE; > > + register_netdevice_notifier(&netvsc_netdev_notifier); > + > ret = vmbus_driver_register(&netvsc_drv); > - if (ret) > + if (ret) { > + unregister_netdevice_notifier(&netvsc_netdev_notifier); > return ret; > + } > > - register_netdevice_notifier(&netvsc_netdev_notifier); > return 0; > } Hi Haiyang Zhang, functionally this change looks good to me, thanks! I'm wondering if we could improve things slightly by using a more idiomatic form for the error path. Something like the following (completely untested!). My reasoning is that this way things are less likely go to wrong if more error conditions are added to this function later. ... register_netdevice_notifier(&netvsc_netdev_notifier); ret = vmbus_driver_register(&netvsc_drv); if (ret) goto err_unregister_netdevice_notifier; return 0; err_unregister_netdevice_notifier: unregister_netdevice_notifier(&netvsc_netdev_notifier); return ret; }