From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Sender: Tejun Heo Date: Mon, 9 Apr 2018 11:56:16 -0700 From: "tj@kernel.org" To: Bart Van Assche Cc: "hch@lst.de" , "maxg@mellanox.com" , "israelr@mellanox.com" , "linux-block@vger.kernel.org" , "stable@vger.kernel.org" , "axboe@kernel.dk" , "sagi@grimberg.me" Subject: Re: [PATCH] blk-mq: Fix recently introduced races in the timeout handling code Message-ID: <20180409185616.GG3126663@devbig577.frc2.facebook.com> References: <20180409052038.5391-1-bart.vanassche@wdc.com> <20180409164737.GE3126663@devbig577.frc2.facebook.com> <4e32290f8d5901fbd16116d1623d37dbfdc1e1b8.camel@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4e32290f8d5901fbd16116d1623d37dbfdc1e1b8.camel@wdc.com> List-ID: Hello, On Mon, Apr 09, 2018 at 05:03:05PM +0000, Bart Van Assche wrote: > My opinion is not only that the two patches that you posted recently do not > fix all the races that are fixed by this patch but also that the races that The race was with the path where the ownership of a timed out request is passed back to normal completion path and those two patches fix that, right? > exist today in the blk-mq timeout handling code cannot be fixed completely > using RCU only. I really don't think that is that complicated. Let's first confirm the race fix and get to narrowing / closing that window. > That race window did not exist in the legacy block layer. I don't think IIRC, it did. It was there when I first started working on libata EH years ago. Thanks. -- tejun