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From: Rusty Russell <rusty@rustcorp.com.au>
To: <torvalds@linux-foundation.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "LKML" <linux-kernel@vger.kernel.org>
Subject: Why does test_bit() take a volatile addr?
Date: Mon, 16 Sep 2013 13:38:35 +0930	[thread overview]
Message-ID: <87ioy11k8s.fsf@rustcorp.com.au> (raw)

Predates git, does anyone remember the rationale?

ie:
        int test_bit(int nr, const volatile unsigned long *addr)

I noticed because gcc failed to elimiate some code in a patch I was
playing with.

I'm nervous about subtle bugs involved in ripping it out, even if noone
knows why.  Should I add __test_bit()?

Thanks,
Rusty.

             reply	other threads:[~2013-09-16  6:38 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-16  4:08 Rusty Russell [this message]
2013-09-16  6:53 ` Why does test_bit() take a volatile addr? Stephen Rothwell
2013-09-16  7:26   ` Michael S. Tsirkin
2013-09-16  8:02     ` Stephen Rothwell
2013-09-16  8:47       ` Michael S. Tsirkin
2013-09-16  8:20 ` Geert Uytterhoeven
2013-09-16  8:37 ` Michael S. Tsirkin
2013-09-16  8:40 ` Oliver Neukum
2013-09-16  8:44   ` Michael S. Tsirkin
2013-09-16  8:49     ` Oliver Neukum
2013-09-16 11:59 ` Linus Torvalds
2013-09-22 21:37 ` Rob Landley
2013-09-23  1:13   ` Rusty Russell

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