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From: "gcc-bugs at tesarici dot cz" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/52080] Stores to bitfields introduce a store-data-race on adjacent data
Date: Thu, 02 Feb 2012 11:01:00 -0000	[thread overview]
Message-ID: <bug-52080-4-zAe1vMEjcN@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-52080-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52080

Petr Tesarik <gcc-bugs at tesarici dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc-bugs at tesarici dot cz

--- Comment #9 from Petr Tesarik <gcc-bugs at tesarici dot cz> 2012-02-02 11:00:50 UTC ---
OK, my minimal test case removed the "volatile" keyword by mistake.

The real code in BTRFS has the volatile for the lock value which precedes the
bitfield, so the corresponding structure would be:

struct x {
    long a;
    volatile unsigned int lock;   /* <- note the "volatile" here */
    unsigned int full : 1;
};

Now, GCC should honour that the value of "lock" can change any time, so it must
not assume that writing back the same value a few cycles later is safe.


  parent reply	other threads:[~2012-02-02 11:01 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-01 10:07 [Bug target/52080] New: " rguenth at gcc dot gnu.org
2012-02-01 10:23 ` [Bug target/52080] " rguenth at gcc dot gnu.org
2012-02-01 10:25 ` rguenth at gcc dot gnu.org
2012-02-01 10:39 ` rguenth at gcc dot gnu.org
2012-02-01 11:13 ` rguenth at gcc dot gnu.org
2012-02-01 17:12 ` ebotcazou at gcc dot gnu.org
2012-02-01 17:45 ` ebotcazou at gcc dot gnu.org
2012-02-01 17:50 ` matz at gcc dot gnu.org
2012-02-01 18:53 ` bergner at gcc dot gnu.org
2012-02-02 11:01 ` gcc-bugs at tesarici dot cz [this message]
2012-02-02 11:11 ` rguenth at gcc dot gnu.org
2012-02-02 12:40 ` gcc-bugs at tesarici dot cz
2012-02-21 12:04 ` rguenth at gcc dot gnu.org
2012-03-14 11:00 ` rguenth at gcc dot gnu.org
2012-03-14 11:01 ` rguenth at gcc dot gnu.org
2012-06-04  8:44 ` rguenth at gcc dot gnu.org
2013-02-19 20:37 ` LpSolit at netscape dot net
2014-02-16 13:17 ` jackie.rosen at hushmail dot com

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