From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH 2/2] block: Avoid deadlocks with bio allocation by stacking drivers Date: Mon, 10 Sep 2012 14:33:49 -0700 Message-ID: <20120910213349.GH16360@google.com> References: <1347055973-11581-1-git-send-email-koverstreet@google.com> <1347055973-11581-3-git-send-email-koverstreet@google.com> <20120908193641.GB12773@dhcp-172-17-108-109.mtv.corp.google.com> <20120910002810.GA23241@moria.home.lan> <20120910172210.GC14103@google.com> <20120910202435.GG16360@google.com> <20120910204010.GA32310@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120910204010.GA32310-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tejun Heo Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, Vivek Goyal , Mikulas Patocka , bharrosh-C4P08NqkoRlBDgjK7y7TUQ@public.gmane.org, david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org List-Id: linux-bcache@vger.kernel.org On Mon, Sep 10, 2012 at 01:40:10PM -0700, Tejun Heo wrote: > Hello, Kent. > > On Mon, Sep 10, 2012 at 01:24:35PM -0700, Kent Overstreet wrote: > > And at that point, why duplicate that line of code? It doesn't matter that > > much, but IMO a goto retry better labels what's actually going on (it's > > something that's not uncommon in the kernel and if I see a retry label > > in a function I pretty immediately have an idea of what's going on). > > > > So we could do > > > > retry: > > p = mempool_alloc(bs->bio_pool, gfp_mask); > > if (!p && gfp_mask != saved_gfp) { > > punt_bios_to_rescuer(bs); > > gfp_mask = saved_gfp; > > goto retry; > > } > > Yes, we do retry loops if that makes the code simpler. Doing that to > save one extra alloc call, I don't think so. "Simpler" isn't really an objective thing though. To me the goto version is more obvious/idiomatic. Eh. I'll do it your way, but consider this a formal objection :p