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powerpc: Implement smp_cond_load_relaxed()

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This implements smp_cond_load_relaxed() with the slowpath busy loop
using the preferred SMT priority pattern.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
[mpe: Make it 64-bit only to fix build errors on 32-bit]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200724131423.1362108-7-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2020-07-24 23:14:23 +10:00 committed by Michael Ellerman
parent 2f6560e652
commit 49a7d46a06
1 changed files with 16 additions and 0 deletions
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16
arch/powerpc/include/asm/barrier.h
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@ -80,6 +80,22 @@ do { \
___p1; \
})
#ifdef CONFIG_PPC64
#define smp_cond_load_relaxed(ptr, cond_expr) ({ \
typeof(ptr) __PTR = (ptr); \
__unqual_scalar_typeof(*ptr) VAL; \
VAL = READ_ONCE(*__PTR); \
if (unlikely(!(cond_expr))) { \
spin_begin(); \
do { \
VAL = READ_ONCE(*__PTR); \
} while (!(cond_expr)); \
spin_end(); \
} \
(typeof(*ptr))VAL; \
})
#endif
#ifdef CONFIG_PPC_BOOK3S_64
#define NOSPEC_BARRIER_SLOT nop
#elif defined(CONFIG_PPC_FSL_BOOK3E)