diff options
| -rw-r--r-- | Documentation/memory-barriers.txt | 14 | ||||
| -rw-r--r-- | drivers/md/dm-writecache.c | 2 | ||||
| -rw-r--r-- | drivers/nvdimm/region_devs.c | 8 | ||||
| -rw-r--r-- | include/asm-generic/barrier.h | 10 |
4 files changed, 29 insertions, 5 deletions
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index eaabc3134294..ff07cd3b2f82 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1935,6 +1935,20 @@ There are some more advanced barrier functions: relaxed I/O accessors and the Documentation/DMA-API.txt file for more information on consistent memory. + (*) pmem_wmb(); + + This is for use with persistent memory to ensure that stores for which + modifications are written to persistent storage reached a platform + durability domain. + + For example, after a non-temporal write to pmem region, we use pmem_wmb() + to ensure that stores have reached a platform durability domain. This ensures + that stores have updated persistent storage before any data access or + data transfer caused by subsequent instructions is initiated. This is + in addition to the ordering done by wmb(). + + For load from persistent memory, existing read memory barriers are sufficient + to ensure read ordering. =============================== IMPLICIT KERNEL MEMORY BARRIERS diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index 74f3c506f084..00534fa4a384 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -536,7 +536,7 @@ static void ssd_commit_superblock(struct dm_writecache *wc) static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios) { if (WC_MODE_PMEM(wc)) - wmb(); + pmem_wmb(); else ssd_commit_flushed(wc, wait_for_ios); } diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 4502f9c4708d..c3237c2b03a6 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -1206,13 +1206,13 @@ int generic_nvdimm_flush(struct nd_region *nd_region) idx = this_cpu_add_return(flush_idx, hash_32(current->pid + idx, 8)); /* - * The first wmb() is needed to 'sfence' all previous writes - * such that they are architecturally visible for the platform - * buffer flush. Note that we've already arranged for pmem + * The pmem_wmb() is needed to 'sfence' all + * previous writes such that they are architecturally visible for + * the platform buffer flush. Note that we've already arranged for pmem * writes to avoid the cache via memcpy_flushcache(). The final * wmb() ensures ordering for the NVDIMM flush write. */ - wmb(); + pmem_wmb(); for (i = 0; i < nd_region->ndr_mappings; i++) if (ndrd_get_flush_wpq(ndrd, i, 0)) writeq(1, ndrd_get_flush_wpq(ndrd, i, idx)); diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 2eacaf7d62f6..b589bb216ee5 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -257,5 +257,15 @@ do { \ }) #endif +/* + * pmem_wmb() ensures that all stores for which the modification + * are written to persistent storage by preceding instructions have + * updated persistent storage before any data access or data transfer + * caused by subsequent instructions is initiated. + */ +#ifndef pmem_wmb +#define pmem_wmb() wmb() +#endif + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_GENERIC_BARRIER_H */ |