From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Josh Triplett <josh@joshtriplett.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
Matthew Wilcox <willy@infradead.org>,
linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>,
linux-mm@kvack.org, Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH 2/2] Introduce __cond_lock_err
Date: Thu, 21 Dec 2017 15:10:50 -0700 [thread overview]
Message-ID: <20171221221050.GD9087@linux.intel.com> (raw)
In-Reply-To: <20171221220015.GA14919@localhost>
On Thu, Dec 21, 2017 at 02:00:16PM -0800, Josh Triplett wrote:
> On Thu, Dec 21, 2017 at 02:48:10PM -0700, Ross Zwisler wrote:
> > On Tue, Dec 19, 2017 at 08:58:23AM -0800, Matthew Wilcox wrote:
> > > From: Matthew Wilcox <mawilcox@microsoft.com>
> > >
> > > The __cond_lock macro expects the function to return 'true' if the lock
> > > was acquired and 'false' if it wasn't. We have another common calling
> > > convention in the kernel, which is returning 0 on success and an errno
> > > on failure. It's hard to use the existing __cond_lock macro for those
> > > kinds of functions, so introduce __cond_lock_err() and convert the
> > > two existing users.
> >
> > This is much cleaner! One quick issue below.
> >
> > > Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
> > > ---
> > > include/linux/compiler_types.h | 2 ++
> > > include/linux/mm.h | 9 ++-------
> > > mm/memory.c | 9 ++-------
> > > 3 files changed, 6 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> > > index 6b79a9bba9a7..ff3c41c78efa 100644
> > > --- a/include/linux/compiler_types.h
> > > +++ b/include/linux/compiler_types.h
> > > @@ -16,6 +16,7 @@
> > > # define __acquire(x) __context__(x,1)
> > > # define __release(x) __context__(x,-1)
> > > # define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
> > > +# define __cond_lock_err(x,c) ((c) ? 1 : ({ __acquire(x); 0; }))
> > ^
> > I think we actually want this to return c here ^
>
> Then you want to use ((c) ?: ...), to avoid evaluating c twice.
Oh, yep, great catch.
next prev parent reply other threads:[~2017-12-21 22:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-19 16:58 [PATCH 1/2] mm: Make follow_pte_pmd an inline Matthew Wilcox
2017-12-19 16:58 ` [PATCH 2/2] Introduce __cond_lock_err Matthew Wilcox
2017-12-21 21:48 ` Ross Zwisler
2017-12-21 22:00 ` Josh Triplett
2017-12-21 22:10 ` Ross Zwisler [this message]
2017-12-22 1:10 ` Matthew Wilcox
2017-12-22 4:21 ` Josh Triplett
2017-12-22 12:31 ` Matthew Wilcox
2017-12-22 13:36 ` Matthew Wilcox
2017-12-23 9:39 ` Josh Triplett
2017-12-23 13:06 ` Matthew Wilcox
2017-12-27 14:38 ` Luc Van Oostenryck
2017-12-27 14:28 ` Luc Van Oostenryck
2017-12-30 7:17 ` Matthew Wilcox
2017-12-19 17:05 ` [PATCH 1/2] mm: Make follow_pte_pmd an inline Joe Perches
2017-12-19 17:12 ` Matthew Wilcox
2017-12-21 21:29 ` Ross Zwisler
2017-12-22 1:07 ` Matthew Wilcox
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