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Add membar_sync 

Provides the missing full barrier variant to the membar primitive set.

While not used right now, this is probably going to change down the
road.

Name taken from Solaris, to follow the existing routines.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Closes #13907
This commit is contained in:
Mateusz Guzik 2022-09-21 00:32:44 +02:00 committed by GitHub
parent 62e2a2881f
commit 402426c7d8
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 15 additions and 0 deletions
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1
include/os/freebsd/spl/sys/atomic.h
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@ -59,6 +59,7 @@ extern uint64_t atomic_cas_64(volatile uint64_t *target, uint64_t cmp,
#define membar_consumer() atomic_thread_fence_acq() #define membar_consumer() atomic_thread_fence_acq()
#define membar_producer() atomic_thread_fence_rel() #define membar_producer() atomic_thread_fence_rel()
#define membar_sync() atomic_thread_fence_seq_cst()
static __inline uint32_t static __inline uint32_t
atomic_add_32_nv(volatile uint32_t *target, int32_t delta) atomic_add_32_nv(volatile uint32_t *target, int32_t delta)

1
include/os/linux/spl/sys/vmsystm.h
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@ -46,6 +46,7 @@
#define membar_consumer() smp_rmb() #define membar_consumer() smp_rmb()
#define membar_producer() smp_wmb() #define membar_producer() smp_wmb()
#define membar_sync() smp_mb()
#define physmem zfs_totalram_pages #define physmem zfs_totalram_pages

6
lib/libspl/atomic.c
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@ -381,6 +381,12 @@ membar_exit(void)
__atomic_thread_fence(__ATOMIC_SEQ_CST); __atomic_thread_fence(__ATOMIC_SEQ_CST);
} }
void
membar_sync(void)
{
__atomic_thread_fence(__ATOMIC_SEQ_CST);
}
void void
membar_producer(void) membar_producer(void)
{ {

7
lib/libspl/include/atomic.h
View File

@ -313,6 +313,13 @@ extern void membar_enter(void);
*/ */
extern void membar_exit(void); extern void membar_exit(void);
/*
* Make all stores and loads emitted prior to the the barrier complete before
* crossing it, while also making sure stores and loads emitted after the
* barrier only start being executed after crossing it.
*/
extern void membar_sync(void);
/* /*
* Arrange that all stores issued before this point in the code reach * Arrange that all stores issued before this point in the code reach
* global visibility before any stores that follow; useful in producer * global visibility before any stores that follow; useful in producer