linux-kernel - [PATCH v2 3/3] x86: remove unneeded flush in arch_copy_from_iter

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Date:   Wed, 26 Oct 2016 10:50:21 -0500
From:   Brian Boylston <brian.boylston@....com>
To:     linux-nvdimm@...ts.01.org
Cc:     linux-kernel@...r.kernel.org, toshi.kani@....com,
        oliver.moreno@....com, Brian Boylston <brian.boylston@....com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Al Viro <viro@...IV.linux.org.uk>,
        Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH v2 3/3] x86: remove unneeded flush in arch_copy_from_iter_pmem()

copy_from_iter_nocache() now uses nocache copies for all types of iovecs
on x86, so the flush in arch_copy_from_iter_pmem() is no longer needed.

Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: <x86@...nel.org>
Cc: Al Viro <viro@...IV.linux.org.uk>
Cc: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Brian Boylston <brian.boylston@....com>
Reviewed-by: Toshi Kani <toshi.kani@....com>
Reported-by: Oliver Moreno <oliver.moreno@....com>
---
 arch/x86/include/asm/pmem.h | 19 +------------------
 1 file changed, 1 insertion(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index 643eba4..2fbf4ae 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -72,15 +72,6 @@ static inline void arch_wb_cache_pmem(void *addr, size_t size)
 		clwb(p);
 }
 
-/*
- * copy_from_iter_nocache() on x86 only uses non-temporal stores for iovec
- * iterators, so for other types (bvec & kvec) we must do a cache write-back.
- */
-static inline bool __iter_needs_pmem_wb(struct iov_iter *i)
-{
-	return iter_is_iovec(i) == false;
-}
-
 /**
  * arch_copy_from_iter_pmem - copy data from an iterator to PMEM
  * @addr:	PMEM destination address
@@ -92,15 +83,7 @@ static inline bool __iter_needs_pmem_wb(struct iov_iter *i)
 static inline size_t arch_copy_from_iter_pmem(void *addr, size_t bytes,
 		struct iov_iter *i)
 {
-	size_t len;
-
-	/* TODO: skip the write-back by always using non-temporal stores */
-	len = copy_from_iter_nocache(addr, bytes, i);
-
-	if (__iter_needs_pmem_wb(i))
-		arch_wb_cache_pmem(addr, bytes);
-
-	return len;
+	return copy_from_iter_nocache(addr, bytes, i);
 }
 
 /**
-- 
2.8.3