From: Matthew Wilcox <willy@infradead.org>
To: David Rientjes <rientjes@google.com>
Cc: Ian Kent <raven@themaw.net>,
autofs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH] autofs4: Use wait_event_killable
Date: Mon, 19 Mar 2018 12:30:31 -0700 [thread overview]
Message-ID: <20180319193031.GC6739@bombadil.infradead.org> (raw)
In-Reply-To: <alpine.DEB.2.20.1803191218210.114201@chino.kir.corp.google.com>
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.
next prev parent reply other threads:[~2018-03-19 19:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-19 19:16 [PATCH] autofs4: Use wait_event_killable Matthew Wilcox
2018-03-19 19:25 ` David Rientjes
2018-03-19 19:30 ` Matthew Wilcox [this message]
2018-03-20 2:42 ` Ian Kent
2018-03-20 1:58 ` Ian Kent
2018-03-20 3:12 ` Matthew Wilcox
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