From: David Laight <David.Laight@ACULAB.COM>
To: 'Waiman Long' <longman@redhat.com>, Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH] locking/rwsem: Fix kernel crash when spinning on RWSEM_OWNER_UNKNOWN
Date: Wed, 15 Jan 2020 16:01:28 +0000 [thread overview]
Message-ID: <8930570b92aa435b941c99dff00c7802@AcuMS.aculab.com> (raw)
In-Reply-To: <4ac00b33-5397-3c69-6cba-cf3d9d375ea9@redhat.com>
From: Waiman Long
> Sent: 15 January 2020 15:48
...
> It depends. I find it hard to read an expression with "&" and "&&"
> without parentheses. Anyway, I will admit that the above code is
> inconsistent in term of how parentheses are used. So I will change that.
Conditionals containing fragments like (a == b && c == d && ...)
are much easier to read without any extra ().
The only problem with && is that when K&R added it to C they didn't
change the priority of & to be higher than == (where it should be).
At that time they could have changed all the existing code...
Modern compilers do warn about (a == b & c).
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-01-15 16:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 19:03 [PATCH] locking/rwsem: Fix kernel crash when spinning on RWSEM_OWNER_UNKNOWN Waiman Long
2020-01-15 6:50 ` Christoph Hellwig
2020-01-15 14:27 ` Waiman Long
2020-01-15 15:16 ` David Laight
2020-01-15 15:47 ` Waiman Long
2020-01-15 16:01 ` David Laight [this message]
2020-01-15 15:28 ` Waiman Long
2020-01-15 15:37 ` Peter Zijlstra
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