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authorPaul Mackerras <paulus@samba.org>2009-06-12 02:00:50 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-06-15 13:27:37 +1000
commit4c75f84f2c781beb230031234ed961d28771a764 (patch)
treebae42cc387d0fdbc206729f2163b3eebefb9a85c /lib/atomic64.c
parente8d1673b9720ec72d85916c6b7d5d476abb2c861 (diff)
powerpc: Add compiler memory barrier to mtmsr macro
On 32-bit non-Book E, local_irq_restore() turns into just mtmsr(), which doesn't currently have a compiler memory barrier. This means that accesses to memory inside a local_irq_save/restore section, or a spin_lock_irqsave/spin_unlock_irqrestore section on UP, can be reordered by the compiler to occur outside that section. To fix this, this adds a compiler memory barrier to mtmsr for both 32-bit and 64-bit. Having a compiler memory barrier in mtmsr makes sense because it will almost always be changing something about the context in which memory accesses are done, so in general we don't want memory accesses getting moved from one side of an mtmsr to the other. With the barrier in mtmsr(), some of the explicit barriers in hw_irq.h are now redundant, so this removes them. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'lib/atomic64.c')
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