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H A D | spinlock.h | 3b885ac1 Sun Aug 12 15:31:17 CDT 2018 John David Anglin <dave.anglin@bell.net> parisc: Remove unnecessary barriers from spinlock.h
Now that mb() is an instruction barrier, it will slow performance if we issue unnecessary barriers.
The spinlock defines have a number of unnecessary barriers. The __ldcw() define is both a hardware and compiler barrier. The mb() barriers in the routines using __ldcw() serve no purpose.
The only barrier needed is the one in arch_spin_unlock(). We need to ensure all accesses are complete prior to releasing the lock.
Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: stable@vger.kernel.org # 4.0+ Signed-off-by: Helge Deller <deller@gmx.de> 3b885ac1 Sun Aug 12 15:31:17 CDT 2018 John David Anglin <dave.anglin@bell.net> parisc: Remove unnecessary barriers from spinlock.h Now that mb() is an instruction barrier, it will slow performance if we issue unnecessary barriers. The spinlock defines have a number of unnecessary barriers. The __ldcw() define is both a hardware and compiler barrier. The mb() barriers in the routines using __ldcw() serve no purpose. The only barrier needed is the one in arch_spin_unlock(). We need to ensure all accesses are complete prior to releasing the lock. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: stable@vger.kernel.org # 4.0+ Signed-off-by: Helge Deller <deller@gmx.de>
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