From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:48378 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965715AbeCSTad (ORCPT ); Mon, 19 Mar 2018 15:30:33 -0400 Date: Mon, 19 Mar 2018 12:30:31 -0700 From: Matthew Wilcox To: David Rientjes Cc: Ian Kent , autofs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox Subject: Re: [PATCH] autofs4: Use wait_event_killable Message-ID: <20180319193031.GC6739@bombadil.infradead.org> References: <20180319191609.23880-1-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Mar 19, 2018 at 12:25:58PM -0700, David Rientjes wrote: > On Mon, 19 Mar 2018, Matthew Wilcox wrote: > > * wq->name.name is NULL iff the lock is already released > > * or the mount has been made catatonic. > > */ > > - if (wq->name.name) { > > - /* Block all but "shutdown" signals while waiting */ > > - unsigned long shutdown_sigs_mask; > > - unsigned long irqflags; > > - sigset_t oldset; > > - [...] > > - > > - wait_event_interruptible(wq->queue, wq->name.name == NULL); [...] > > - } else { > > - pr_debug("skipped sleeping\n"); > > - } > > - > > + wait_event_killable(wq->queue, wq->name.name == NULL); > > I understand converting the wait_event_interruptible() to > wait_event_killable(), but why was the above wait_event_interruptible() > only called when wq->name.name != NULL? My guess is that it was to avoid the overhead of diddling the signal set when wq->name.name was already NULL. I don't really kow though, it predates git history and I'm too lazy to go and poke through the historical repos to see if that reason was captured by BitKeeper. > wait_event_{killable,interruptible}() will return without sleeping when > wq->name.name == NULL, so I suppose it has something to do with the > comment above it.