Return-Path: Date: Thu, 19 Jul 2018 15:19:04 +0200 From: "hch@lst.de" To: Keith Busch Cc: Bart Van Assche , "hch@lst.de" , "keith.busch@intel.com" , "linux-block@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "axboe@kernel.dk" , "ming.lei@redhat.com" Subject: Re: [RFC PATCH 3/3] blk-mq: Remove generation seqeunce Message-ID: <20180719131903.GB13129@lst.de> References: <7cad25b821c3a640e036f28ff1bbe51e7362d25d.camel@wdc.com> <20180713154346.GA18955@localhost.localdomain> <20180713184712.GA19419@localhost.localdomain> <291a13b35af1b65fbbe99a3a9cfc7d570a620cd9.camel@wdc.com> <20180713235807.GA19967@localhost.localdomain> <20180718195650.GA20336@lst.de> <20180718205321.GA32160@localhost.localdomain> <20180718211711.GB32160@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180718211711.GB32160@localhost.localdomain> List-ID: On Wed, Jul 18, 2018 at 03:17:11PM -0600, Keith Busch wrote: > And there may be other drivers that don't want their completions > ignored, so breaking them again is also a step in the wrong direction. > > There are not that many blk-mq drivers, so we can go through them all. I think the point is that SCSI is the biggest user by both the number of low-level drivers sitting under the midlayer, and also by usage. We need to be very careful not to break it. Note that this doesn't mean that I don't want to eventually move away from just ignoring completions in timeout state for SCSI. I'd just rather rever 4.18 to a clean known state instead of doctoring around late in the rc phase. > Most don't even implement .timeout, so they never know that condition > ever happened. Others always return BLK_EH_RESET_TIMER without doing > anythign else, so the 'new' behavior would have to be better for those, > too. And we should never even hit the timeout handler for those as it is rather pointless (although it looks we currently do..).