From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Soheil Hassas Yeganeh <soheil.kdev@gmail.com>,
Arnd Bergmann <arnd@arndb.de>, Shuo Chen <shuochen@google.com>,
linux-man@vger.kernel.org
Subject: Re: [PATCH v3 1/2] epoll: add nsec timeout support with epoll_pwait2
Date: Wed, 18 Nov 2020 10:10:52 -0500 [thread overview]
Message-ID: <CA+FuTSdxNBvNMy341EHeiKOWZ19H++aw-tfr6Fx1mFmbg-z4zQ@mail.gmail.com> (raw)
In-Reply-To: <20201118150041.GF29991@casper.infradead.org>
On Wed, Nov 18, 2020 at 10:00 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Wed, Nov 18, 2020 at 09:46:15AM -0500, Willem de Bruijn wrote:
> > -static inline struct timespec64 ep_set_mstimeout(long ms)
> > +static inline struct timespec64 ep_set_nstimeout(s64 timeout)
> > {
> > - struct timespec64 now, ts = {
> > - .tv_sec = ms / MSEC_PER_SEC,
> > - .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
> > - };
> > + struct timespec64 now, ts;
> >
> > + ts = ns_to_timespec64(timeout);
> > ktime_get_ts64(&now);
> > return timespec64_add_safe(now, ts);
> > }
>
> Why do you pass around an s64 for timeout, converting it to and from
> a timespec64 instead of passing around a timespec64?
I implemented both approaches. The alternative was no simpler.
Conversion in existing epoll_wait, epoll_pwait and epoll_pwait
(compat) becomes a bit more complex and adds a stack variable there if
passing the timespec64 by reference. And in ep_poll the ternary
timeout test > 0, 0, < 0 now requires checking both tv_secs and
tv_nsecs. Based on that, I found this simpler. But no strong
preference.
next prev parent reply other threads:[~2020-11-18 15:11 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 14:46 [PATCH v3 0/2] add epoll_pwait2 syscall Willem de Bruijn
2020-11-18 14:46 ` [PATCH v3 1/2] epoll: add nsec timeout support with epoll_pwait2 Willem de Bruijn
2020-11-18 15:00 ` Matthew Wilcox
2020-11-18 15:10 ` Willem de Bruijn [this message]
2020-11-18 15:37 ` Arnd Bergmann
2020-11-18 15:59 ` David Laight
2020-11-19 14:19 ` Willem de Bruijn
2020-11-19 14:31 ` Matthew Wilcox
2020-11-19 15:37 ` Willem de Bruijn
2020-11-19 15:45 ` Arnd Bergmann
2020-11-19 20:13 ` Willem de Bruijn
2020-11-20 8:13 ` Arnd Bergmann
2020-11-20 16:01 ` Willem de Bruijn
2020-11-20 19:23 ` Arnd Bergmann
2020-11-20 22:28 ` Willem de Bruijn
2020-11-21 9:27 ` Arnd Bergmann
2020-12-10 17:33 ` Willem de Bruijn
2020-12-10 20:34 ` Arnd Bergmann
2020-12-10 22:59 ` Willem de Bruijn
2021-01-11 20:06 ` Willem de Bruijn
2020-11-18 16:21 ` Willem de Bruijn
2020-11-18 16:50 ` Arnd Bergmann
2020-11-19 3:22 ` Willem de Bruijn
2020-11-18 14:46 ` [PATCH manpages RFC] epoll_wait.2: add epoll_pwait2 Willem de Bruijn
2020-11-18 14:46 ` [PATCH v3 2/2] selftests/filesystems: expand epoll with epoll_pwait2 Willem de Bruijn
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