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Subject[PATCH v2 14/17] pmem: kill wmb_pmem()
From
Date
All users have been replaced with flushing in the pmem driver.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
arch/x86/include/asm/pmem.h | 36 ++-------------------------------
include/linux/pmem.h | 47 ++++---------------------------------------
2 files changed, 6 insertions(+), 77 deletions(-)

diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index fbc5e92e1ecc..a8cf2a6b14d9 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -26,8 +26,7 @@
* @n: length of the copy in bytes
*
* Copy data to persistent memory media via non-temporal stores so that
- * a subsequent arch_wmb_pmem() can flush cpu and memory controller
- * write buffers to guarantee durability.
+ * a subsequent pmem driver flush operation will drain posted write queues.
*/
static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
size_t n)
@@ -57,32 +56,12 @@ static inline int arch_memcpy_from_pmem(void *dst, const void __pmem *src,
}

/**
- * arch_wmb_pmem - synchronize writes to persistent memory
- *
- * After a series of arch_memcpy_to_pmem() operations this drains data
- * from cpu write buffers and any platform (memory controller) buffers
- * to ensure that written data is durable on persistent memory media.
- */
-static inline void arch_wmb_pmem(void)
-{
- /*
- * wmb() to 'sfence' all previous writes such that they are
- * architecturally visible to 'pcommit'. Note, that we've
- * already arranged for pmem writes to avoid the cache via
- * arch_memcpy_to_pmem().
- */
- wmb();
- pcommit_sfence();
-}
-
-/**
* arch_wb_cache_pmem - write back a cache range with CLWB
* @vaddr: virtual start address
* @size: number of bytes to write back
*
* Write back a cache range using the CLWB (cache line write back)
- * instruction. This function requires explicit ordering with an
- * arch_wmb_pmem() call.
+ * instruction.
*/
static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
{
@@ -113,7 +92,6 @@ static inline bool __iter_needs_pmem_wb(struct iov_iter *i)
* @i: iterator with source data
*
* Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
- * This function requires explicit ordering with an arch_wmb_pmem() call.
*/
static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
struct iov_iter *i)
@@ -136,7 +114,6 @@ static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
* @size: number of bytes to zero
*
* Write zeros into the memory range starting at 'addr' for 'size' bytes.
- * This function requires explicit ordering with an arch_wmb_pmem() call.
*/
static inline void arch_clear_pmem(void __pmem *addr, size_t size)
{
@@ -150,14 +127,5 @@ static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
{
clflush_cache_range((void __force *) addr, size);
}
-
-static inline bool __arch_has_wmb_pmem(void)
-{
- /*
- * We require that wmb() be an 'sfence', that is only guaranteed on
- * 64-bit builds
- */
- return static_cpu_has(X86_FEATURE_PCOMMIT);
-}
#endif /* CONFIG_ARCH_HAS_PMEM_API */
#endif /* __ASM_X86_PMEM_H__ */
diff --git a/include/linux/pmem.h b/include/linux/pmem.h
index 57d146fe44dd..9e3ea94b8157 100644
--- a/include/linux/pmem.h
+++ b/include/linux/pmem.h
@@ -26,16 +26,6 @@
* calling these symbols with arch_has_pmem_api() and redirect to the
* implementation in asm/pmem.h.
*/
-static inline bool __arch_has_wmb_pmem(void)
-{
- return false;
-}
-
-static inline void arch_wmb_pmem(void)
-{
- BUG();
-}
-
static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
size_t n)
{
@@ -101,20 +91,6 @@ static inline int memcpy_from_pmem(void *dst, void __pmem const *src,
return default_memcpy_from_pmem(dst, src, size);
}

-/**
- * arch_has_wmb_pmem - true if wmb_pmem() ensures durability
- *
- * For a given cpu implementation within an architecture it is possible
- * that wmb_pmem() resolves to a nop. In the case this returns
- * false, pmem api users are unable to ensure durability and may want to
- * fall back to a different data consistency model, or otherwise notify
- * the user.
- */
-static inline bool arch_has_wmb_pmem(void)
-{
- return arch_has_pmem_api() && __arch_has_wmb_pmem();
-}
-
/*
* These defaults seek to offer decent performance and minimize the
* window between i/o completion and writes being durable on media.
@@ -152,7 +128,7 @@ static inline void default_clear_pmem(void __pmem *addr, size_t size)
* being effectively evicted from, or never written to, the processor
* cache hierarchy after the copy completes. After memcpy_to_pmem()
* data may still reside in cpu or platform buffers, so this operation
- * must be followed by a wmb_pmem().
+ * must be followed by a blkdev_issue_flush() on the pmem block device.
*/
static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
{
@@ -163,28 +139,13 @@ static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
}

/**
- * wmb_pmem - synchronize writes to persistent memory
- *
- * After a series of memcpy_to_pmem() operations this drains data from
- * cpu write buffers and any platform (memory controller) buffers to
- * ensure that written data is durable on persistent memory media.
- */
-static inline void wmb_pmem(void)
-{
- if (arch_has_wmb_pmem())
- arch_wmb_pmem();
- else
- wmb();
-}
-
-/**
* copy_from_iter_pmem - copy data from an iterator to PMEM
* @addr: PMEM destination address
* @bytes: number of bytes to copy
* @i: iterator with source data
*
* Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
- * This function requires explicit ordering with a wmb_pmem() call.
+ * See blkdev_issue_flush() note for memcpy_to_pmem().
*/
static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
struct iov_iter *i)
@@ -200,7 +161,7 @@ static inline size_t copy_from_iter_pmem(void __pmem *addr, size_t bytes,
* @size: number of bytes to zero
*
* Write zeros into the memory range starting at 'addr' for 'size' bytes.
- * This function requires explicit ordering with a wmb_pmem() call.
+ * See blkdev_issue_flush() note for memcpy_to_pmem().
*/
static inline void clear_pmem(void __pmem *addr, size_t size)
{
@@ -230,7 +191,7 @@ static inline void invalidate_pmem(void __pmem *addr, size_t size)
* @size: number of bytes to write back
*
* Write back the processor cache range starting at 'addr' for 'size' bytes.
- * This function requires explicit ordering with a wmb_pmem() call.
+ * See blkdev_issue_flush() note for memcpy_to_pmem().
*/
static inline void wb_cache_pmem(void __pmem *addr, size_t size)
{
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