From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH 3/9] IB: add a helper to safely drain a QP Date: Wed, 18 Nov 2015 09:59:15 +0200 Message-ID: <564C2FD3.6090608@dev.mellanox.co.il> References: <1447422410-20891-1-git-send-email-hch@lst.de> <1447422410-20891-4-git-send-email-hch@lst.de> <564851BB.1020004@dev.mellanox.co.il> <564B5E7D.9030309@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <564B5E7D.9030309-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche , Christoph Hellwig , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: axboe-b10kYP2dOMg@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 17/11/2015 19:06, Bart Van Assche wrote: > On 11/15/2015 01:34 AM, Sagi Grimberg wrote: >> This is taken from srp, and srp drains using a recv wr due to a race >> causing a use-after-free condition in srp which re-posts a recv buffer >> in the recv completion handler. > > Hello Sagi, > > Would it be possible to clarify this ? Does this refer to an existing > race or a race that would only occur if the code would be modified ? I was referring to a bug that srp_destroy_qp() was design to address: commit 7dad6b2e440d810273946b0e7092a8fe043c3b8a Author: Bart Van Assche Date: Tue Oct 21 18:00:35 2014 +0200 IB/srp: Fix a race condition triggered by destroying a queue pair At least LID reassignment can trigger a race condition in the SRP initiator driver, namely the receive completion handler trying to post a request on a QP during or after QP destruction and before the CQ's have been destroyed. Avoid this race by modifying a QP into the error state and by waiting until all receive completions have been processed before destroying a QP. Reported-by: Max Gurtuvoy Signed-off-by: Bart Van Assche Reviewed-by: Sagi Grimberg Signed-off-by: Christoph Hellwig -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html