4.9-stable patches

added patches:
	parisc-remove-unnecessary-barriers-from-spinlock.h.patch

diff --git a/queue-4.9/parisc-remove-unnecessary-barriers-from-spinlock.h.patch b/queue-4.9/parisc-remove-unnecessary-barriers-from-spinlock.h.patch
new file mode 100644 (file)
index 0000000..c42c1ca
--- /dev/null
+++ b/queue-4.9/parisc-remove-unnecessary-barriers-from-spinlock.h.patch
@@ -0,0 +1,71 @@
+From 3b885ac1dc35b87a39ee176a6c7e2af9c789d8b8 Mon Sep 17 00:00:00 2001
+From: John David Anglin <dave.anglin@bell.net>
+Date: Sun, 12 Aug 2018 16:31:17 -0400
+Subject: parisc: Remove unnecessary barriers from spinlock.h
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: John David Anglin <dave.anglin@bell.net>
+
+commit 3b885ac1dc35b87a39ee176a6c7e2af9c789d8b8 upstream.
+
+Now that mb() is an instruction barrier, it will slow performance if we issue
+unnecessary barriers.
+
+The spinlock defines have a number of unnecessary barriers.  The __ldcw()
+define is both a hardware and compiler barrier.  The mb() barriers in the
+routines using __ldcw() serve no purpose.
+
+The only barrier needed is the one in arch_spin_unlock().  We need to ensure
+all accesses are complete prior to releasing the lock.
+
+Signed-off-by: John David Anglin <dave.anglin@bell.net>
+Cc: stable@vger.kernel.org # 4.0+
+Signed-off-by: Helge Deller <deller@gmx.de>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/parisc/include/asm/spinlock.h |    8 ++------
+ 1 file changed, 2 insertions(+), 6 deletions(-)
+
+--- a/arch/parisc/include/asm/spinlock.h
++++ b/arch/parisc/include/asm/spinlock.h
+@@ -26,7 +26,6 @@ static inline void arch_spin_lock_flags(
+ {
+       volatile unsigned int *a;
+ 
+-      mb();
+       a = __ldcw_align(x);
+       while (__ldcw(a) == 0)
+               while (*a == 0)
+@@ -36,16 +35,15 @@ static inline void arch_spin_lock_flags(
+                               local_irq_disable();
+                       } else
+                               cpu_relax();
+-      mb();
+ }
+ 
+ static inline void arch_spin_unlock(arch_spinlock_t *x)
+ {
+       volatile unsigned int *a;
+-      mb();
++
+       a = __ldcw_align(x);
+-      *a = 1;
+       mb();
++      *a = 1;
+ }
+ 
+ static inline int arch_spin_trylock(arch_spinlock_t *x)
+@@ -53,10 +51,8 @@ static inline int arch_spin_trylock(arch
+       volatile unsigned int *a;
+       int ret;
+ 
+-      mb();
+       a = __ldcw_align(x);
+         ret = __ldcw(a) != 0;
+-      mb();
+ 
+       return ret;
+ }

diff --git a/queue-4.9/series b/queue-4.9/series
index 1405d30d5fcec7b3ea2797f81a58a239452c3ae5..848987841a9e0a601fb88af6c9cbb954b1464085 100644 (file)
--- a/queue-4.9/series
+++ b/queue-4.9/series
@@ -122,3 +122,4 @@ parisc-remove-ordered-stores-from-syscall.s.patch
 xfrm_user-prevent-leaking-2-bytes-of-kernel-memory.patch
 netfilter-conntrack-dccp-treat-sync-syncack-as-invalid-if-no-prior-state.patch
 packet-refine-ring-v3-block-size-test-to-hold-one-frame.patch
+parisc-remove-unnecessary-barriers-from-spinlock.h.patch