* [PATCH v3 33/41] virtio_ring: use virt_store_mb
From: Michael S. Tsirkin @ 2016-01-10 14:21 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
We need a full barrier after writing out event index, using
virt_store_mb there seems better than open-coding. As usual, we need a
wrapper to account for strong barriers.
It's tempting to use this in vhost as well, for that, we'll
need a variant of smp_store_mb that works on __user pointers.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/virtio_ring.h | 11 +++++++++++
drivers/virtio/virtio_ring.c | 15 +++++++++------
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index f3fa55b..a156e2b 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -45,6 +45,17 @@ static inline void virtio_wmb(bool weak_barriers)
wmb();
}
+static inline void virtio_store_mb(bool weak_barriers,
+ __virtio16 *p, __virtio16 v)
+{
+ if (weak_barriers) {
+ virt_store_mb(*p, v);
+ } else {
+ WRITE_ONCE(*p, v);
+ mb();
+ }
+}
+
struct virtio_device;
struct virtqueue;
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index ee663c4..e12e385 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -517,10 +517,10 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
/* If we expect an interrupt for the next entry, tell host
* by writing event index and flush out the write before
* the read in the next get_buf call. */
- if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
- vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, vq->last_used_idx);
- virtio_mb(vq->weak_barriers);
- }
+ if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+ virtio_store_mb(vq->weak_barriers,
+ &vring_used_event(&vq->vring),
+ cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
#ifdef DEBUG
vq->last_add_time_valid = false;
@@ -653,8 +653,11 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
}
/* TODO: tune this threshold */
bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4;
- vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs);
- virtio_mb(vq->weak_barriers);
+
+ virtio_store_mb(vq->weak_barriers,
+ &vring_used_event(&vq->vring),
+ cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
+
if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) {
END_USE(vq);
return false;
--
MST
^ permalink raw reply related
* [PATCH v3 32/41] sh: move xchg_cmpxchg to a header by itself
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, Rich Felker, linux-ia64, linux-sh, Peter Zijlstra,
virtualization, H. Peter Anvin, sparclinux, linux-arch,
linux-s390, Russell King - ARM Linux, Arnd Bergmann, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
Looks like future sh variants will support a 4-byte cas which will be
used to implement 1 and 2 byte xchg.
This is exactly what we do for llsc now, move the portable part of the
code into a separate header so it's easy to reuse.
Suggested-by: Rich Felker <dalias@libc.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
arch/sh/include/asm/cmpxchg-llsc.h | 35 +-------------------------
arch/sh/include/asm/cmpxchg-xchg.h | 51 ++++++++++++++++++++++++++++++++++++++
2 files changed, 52 insertions(+), 34 deletions(-)
create mode 100644 arch/sh/include/asm/cmpxchg-xchg.h
diff --git a/arch/sh/include/asm/cmpxchg-llsc.h b/arch/sh/include/asm/cmpxchg-llsc.h
index e754794..fcfd322 100644
--- a/arch/sh/include/asm/cmpxchg-llsc.h
+++ b/arch/sh/include/asm/cmpxchg-llsc.h
@@ -1,9 +1,6 @@
#ifndef __ASM_SH_CMPXCHG_LLSC_H
#define __ASM_SH_CMPXCHG_LLSC_H
-#include <linux/bitops.h>
-#include <asm/byteorder.h>
-
static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
{
unsigned long retval;
@@ -50,36 +47,6 @@ __cmpxchg_u32(volatile u32 *m, unsigned long old, unsigned long new)
return retval;
}
-static inline u32 __xchg_cmpxchg(volatile void *ptr, u32 x, int size)
-{
- int off = (unsigned long)ptr % sizeof(u32);
- volatile u32 *p = ptr - off;
-#ifdef __BIG_ENDIAN
- int bitoff = (sizeof(u32) - 1 - off) * BITS_PER_BYTE;
-#else
- int bitoff = off * BITS_PER_BYTE;
-#endif
- u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff;
- u32 oldv, newv;
- u32 ret;
-
- do {
- oldv = READ_ONCE(*p);
- ret = (oldv & bitmask) >> bitoff;
- newv = (oldv & ~bitmask) | (x << bitoff);
- } while (__cmpxchg_u32(p, oldv, newv) != oldv);
-
- return ret;
-}
-
-static inline unsigned long xchg_u16(volatile u16 *m, unsigned long val)
-{
- return __xchg_cmpxchg(m, val, sizeof *m);
-}
-
-static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
-{
- return __xchg_cmpxchg(m, val, sizeof *m);
-}
+#include <asm/cmpxchg-xchg.h>
#endif /* __ASM_SH_CMPXCHG_LLSC_H */
diff --git a/arch/sh/include/asm/cmpxchg-xchg.h b/arch/sh/include/asm/cmpxchg-xchg.h
new file mode 100644
index 0000000..7219719
--- /dev/null
+++ b/arch/sh/include/asm/cmpxchg-xchg.h
@@ -0,0 +1,51 @@
+#ifndef __ASM_SH_CMPXCHG_XCHG_H
+#define __ASM_SH_CMPXCHG_XCHG_H
+
+/*
+ * Copyright (C) 2016 Red Hat, Inc.
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See the
+ * file "COPYING" in the main directory of this archive for more details.
+ */
+#include <linux/bitops.h>
+#include <asm/byteorder.h>
+
+/*
+ * Portable implementations of 1 and 2 byte xchg using a 4 byte cmpxchg.
+ * Note: this header isn't self-contained: before including it, __cmpxchg_u32
+ * must be defined first.
+ */
+static inline u32 __xchg_cmpxchg(volatile void *ptr, u32 x, int size)
+{
+ int off = (unsigned long)ptr % sizeof(u32);
+ volatile u32 *p = ptr - off;
+#ifdef __BIG_ENDIAN
+ int bitoff = (sizeof(u32) - 1 - off) * BITS_PER_BYTE;
+#else
+ int bitoff = off * BITS_PER_BYTE;
+#endif
+ u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff;
+ u32 oldv, newv;
+ u32 ret;
+
+ do {
+ oldv = READ_ONCE(*p);
+ ret = (oldv & bitmask) >> bitoff;
+ newv = (oldv & ~bitmask) | (x << bitoff);
+ } while (__cmpxchg_u32(p, oldv, newv) != oldv);
+
+ return ret;
+}
+
+static inline unsigned long xchg_u16(volatile u16 *m, unsigned long val)
+{
+ return __xchg_cmpxchg(m, val, sizeof *m);
+}
+
+static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
+{
+ return __xchg_cmpxchg(m, val, sizeof *m);
+}
+
+#endif /* __ASM_SH_CMPXCHG_XCHG_H */
--
MST
^ permalink raw reply related
* [PATCH v3 31/41] sh: support 1 and 2 byte xchg
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, Rich Felker, linux-ia64, linux-sh, Peter Zijlstra,
virtualization, H. Peter Anvin, sparclinux, linux-arch,
linux-s390, Russell King - ARM Linux, Arnd Bergmann, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This completes the xchg implementation for sh architecture. Note: The
llsc variant is tricky since this only supports 4 byte atomics, the
existing implementation of 1 byte xchg is wrong: we need to do a 4 byte
cmpxchg and retry if any bytes changed meanwhile.
Write this in C for clarity.
Suggested-by: Rich Felker <dalias@libc.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
arch/sh/include/asm/cmpxchg-grb.h | 22 +++++++++++++++
arch/sh/include/asm/cmpxchg-irq.h | 11 ++++++++
arch/sh/include/asm/cmpxchg-llsc.h | 58 +++++++++++++++++++++++---------------
arch/sh/include/asm/cmpxchg.h | 3 ++
4 files changed, 72 insertions(+), 22 deletions(-)
diff --git a/arch/sh/include/asm/cmpxchg-grb.h b/arch/sh/include/asm/cmpxchg-grb.h
index f848dec..2ed557b 100644
--- a/arch/sh/include/asm/cmpxchg-grb.h
+++ b/arch/sh/include/asm/cmpxchg-grb.h
@@ -23,6 +23,28 @@ static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
return retval;
}
+static inline unsigned long xchg_u16(volatile u16 *m, unsigned long val)
+{
+ unsigned long retval;
+
+ __asm__ __volatile__ (
+ " .align 2 \n\t"
+ " mova 1f, r0 \n\t" /* r0 = end point */
+ " mov r15, r1 \n\t" /* r1 = saved sp */
+ " mov #-6, r15 \n\t" /* LOGIN */
+ " mov.w @%1, %0 \n\t" /* load old value */
+ " extu.w %0, %0 \n\t" /* extend as unsigned */
+ " mov.w %2, @%1 \n\t" /* store new value */
+ "1: mov r1, r15 \n\t" /* LOGOUT */
+ : "=&r" (retval),
+ "+r" (m),
+ "+r" (val) /* inhibit r15 overloading */
+ :
+ : "memory" , "r0", "r1");
+
+ return retval;
+}
+
static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
{
unsigned long retval;
diff --git a/arch/sh/include/asm/cmpxchg-irq.h b/arch/sh/include/asm/cmpxchg-irq.h
index bd11f63..f888772 100644
--- a/arch/sh/include/asm/cmpxchg-irq.h
+++ b/arch/sh/include/asm/cmpxchg-irq.h
@@ -14,6 +14,17 @@ static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
return retval;
}
+static inline unsigned long xchg_u16(volatile u16 *m, unsigned long val)
+{
+ unsigned long flags, retval;
+
+ local_irq_save(flags);
+ retval = *m;
+ *m = val;
+ local_irq_restore(flags);
+ return retval;
+}
+
static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
{
unsigned long flags, retval;
diff --git a/arch/sh/include/asm/cmpxchg-llsc.h b/arch/sh/include/asm/cmpxchg-llsc.h
index 4713666..e754794 100644
--- a/arch/sh/include/asm/cmpxchg-llsc.h
+++ b/arch/sh/include/asm/cmpxchg-llsc.h
@@ -1,6 +1,9 @@
#ifndef __ASM_SH_CMPXCHG_LLSC_H
#define __ASM_SH_CMPXCHG_LLSC_H
+#include <linux/bitops.h>
+#include <asm/byteorder.h>
+
static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
{
unsigned long retval;
@@ -22,29 +25,8 @@ static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
return retval;
}
-static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
-{
- unsigned long retval;
- unsigned long tmp;
-
- __asm__ __volatile__ (
- "1: \n\t"
- "movli.l @%2, %0 ! xchg_u8 \n\t"
- "mov %0, %1 \n\t"
- "mov %3, %0 \n\t"
- "movco.l %0, @%2 \n\t"
- "bf 1b \n\t"
- "synco \n\t"
- : "=&z"(tmp), "=&r" (retval)
- : "r" (m), "r" (val & 0xff)
- : "t", "memory"
- );
-
- return retval;
-}
-
static inline unsigned long
-__cmpxchg_u32(volatile int *m, unsigned long old, unsigned long new)
+__cmpxchg_u32(volatile u32 *m, unsigned long old, unsigned long new)
{
unsigned long retval;
unsigned long tmp;
@@ -68,4 +50,36 @@ __cmpxchg_u32(volatile int *m, unsigned long old, unsigned long new)
return retval;
}
+static inline u32 __xchg_cmpxchg(volatile void *ptr, u32 x, int size)
+{
+ int off = (unsigned long)ptr % sizeof(u32);
+ volatile u32 *p = ptr - off;
+#ifdef __BIG_ENDIAN
+ int bitoff = (sizeof(u32) - 1 - off) * BITS_PER_BYTE;
+#else
+ int bitoff = off * BITS_PER_BYTE;
+#endif
+ u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff;
+ u32 oldv, newv;
+ u32 ret;
+
+ do {
+ oldv = READ_ONCE(*p);
+ ret = (oldv & bitmask) >> bitoff;
+ newv = (oldv & ~bitmask) | (x << bitoff);
+ } while (__cmpxchg_u32(p, oldv, newv) != oldv);
+
+ return ret;
+}
+
+static inline unsigned long xchg_u16(volatile u16 *m, unsigned long val)
+{
+ return __xchg_cmpxchg(m, val, sizeof *m);
+}
+
+static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
+{
+ return __xchg_cmpxchg(m, val, sizeof *m);
+}
+
#endif /* __ASM_SH_CMPXCHG_LLSC_H */
diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h
index 85c97b18..5225916 100644
--- a/arch/sh/include/asm/cmpxchg.h
+++ b/arch/sh/include/asm/cmpxchg.h
@@ -27,6 +27,9 @@ extern void __xchg_called_with_bad_pointer(void);
case 4: \
__xchg__res = xchg_u32(__xchg_ptr, x); \
break; \
+ case 2: \
+ __xchg__res = xchg_u16(__xchg_ptr, x); \
+ break; \
case 1: \
__xchg__res = xchg_u8(__xchg_ptr, x); \
break; \
--
MST
^ permalink raw reply related
* [PATCH v3 30/41] virtio_ring: update weak barriers to use virt_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, Alexander Duyck,
virtualization, H. Peter Anvin, sparclinux, linux-arch,
linux-s390, Russell King - ARM Linux, Arnd Bergmann, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
virtio ring uses smp_wmb on SMP and wmb on !SMP,
the reason for the later being that it might be
talking to another kernel on the same SMP machine.
This is exactly what virt_xxx barriers do,
so switch to these instead of homegrown ifdef hacks.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/virtio_ring.h | 25 ++++---------------------
1 file changed, 4 insertions(+), 21 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 67e06fe..f3fa55b 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -12,7 +12,7 @@
* anyone care?
*
* For virtio_pci on SMP, we don't need to order with respect to MMIO
- * accesses through relaxed memory I/O windows, so smp_mb() et al are
+ * accesses through relaxed memory I/O windows, so virt_mb() et al are
* sufficient.
*
* For using virtio to talk to real devices (eg. other heterogeneous
@@ -21,11 +21,10 @@
* actually quite cheap.
*/
-#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
if (weak_barriers)
- smp_mb();
+ virt_mb();
else
mb();
}
@@ -33,7 +32,7 @@ static inline void virtio_mb(bool weak_barriers)
static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
- smp_rmb();
+ virt_rmb();
else
rmb();
}
@@ -41,26 +40,10 @@ static inline void virtio_rmb(bool weak_barriers)
static inline void virtio_wmb(bool weak_barriers)
{
if (weak_barriers)
- smp_wmb();
+ virt_wmb();
else
wmb();
}
-#else
-static inline void virtio_mb(bool weak_barriers)
-{
- mb();
-}
-
-static inline void virtio_rmb(bool weak_barriers)
-{
- rmb();
-}
-
-static inline void virtio_wmb(bool weak_barriers)
-{
- wmb();
-}
-#endif
struct virtio_device;
struct virtqueue;
--
MST
^ permalink raw reply related
* [PATCH v3 29/41] Revert "virtio_ring: Update weak barriers to use dma_wmb/rmb"
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, Alexander Duyck,
virtualization, H. Peter Anvin, sparclinux, linux-arch,
linux-s390, Russell King - ARM Linux, Arnd Bergmann, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This reverts commit 9e1a27ea42691429e31f158cce6fc61bc79bb2e9.
While that commit optimizes !CONFIG_SMP, it mixes
up DMA and SMP concepts, making the code hard
to figure out.
A better way to optimize this is with the new __smp_XXX
barriers.
As a first step, go back to full rmb/wmb barriers
for !SMP.
We switch to __smp_XXX barriers in the next patch.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/virtio_ring.h | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 8e50888..67e06fe 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -21,20 +21,19 @@
* actually quite cheap.
*/
+#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
-#ifdef CONFIG_SMP
if (weak_barriers)
smp_mb();
else
-#endif
mb();
}
static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
- dma_rmb();
+ smp_rmb();
else
rmb();
}
@@ -42,10 +41,26 @@ static inline void virtio_rmb(bool weak_barriers)
static inline void virtio_wmb(bool weak_barriers)
{
if (weak_barriers)
- dma_wmb();
+ smp_wmb();
else
wmb();
}
+#else
+static inline void virtio_mb(bool weak_barriers)
+{
+ mb();
+}
+
+static inline void virtio_rmb(bool weak_barriers)
+{
+ rmb();
+}
+
+static inline void virtio_wmb(bool weak_barriers)
+{
+ wmb();
+}
+#endif
struct virtio_device;
struct virtqueue;
--
MST
^ permalink raw reply related
* [PATCH v3 28/41] asm-generic: implement virt_xxx memory barriers
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, Jonathan Corbet, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, linux-doc,
Joe Perches, linuxppc-dev
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
Guests running within virtual machines might be affected by SMP effects even if
the guest itself is compiled without SMP support. This is an artifact of
interfacing with an SMP host while running an UP kernel. Using mandatory
barriers for this use-case would be possible but is often suboptimal.
In particular, virtio uses a bunch of confusing ifdefs to work around
this, while xen just uses the mandatory barriers.
To better handle this case, low-level virt_mb() etc macros are made available.
These are implemented trivially using the low-level __smp_xxx macros,
the purpose of these wrappers is to annotate those specific cases.
These have the same effect as smp_mb() etc when SMP is enabled, but generate
identical code for SMP and non-SMP systems. For example, virtual machine guests
should use virt_mb() rather than smp_mb() when synchronizing against a
(possibly SMP) host.
Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/asm-generic/barrier.h | 11 +++++++++++
Documentation/memory-barriers.txt | 28 +++++++++++++++++++++++-----
2 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 8752964..1cceca14 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -196,5 +196,16 @@ do { \
#endif
+/* Barriers for virtual machine guests when talking to an SMP host */
+#define virt_mb() __smp_mb()
+#define virt_rmb() __smp_rmb()
+#define virt_wmb() __smp_wmb()
+#define virt_read_barrier_depends() __smp_read_barrier_depends()
+#define virt_store_mb(var, value) __smp_store_mb(var, value)
+#define virt_mb__before_atomic() __smp_mb__before_atomic()
+#define virt_mb__after_atomic() __smp_mb__after_atomic()
+#define virt_store_release(p, v) __smp_store_release(p, v)
+#define virt_load_acquire(p) __smp_load_acquire(p)
+
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_GENERIC_BARRIER_H */
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index aef9487..8f4a93a 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1655,17 +1655,18 @@ macro is a good place to start looking.
SMP memory barriers are reduced to compiler barriers on uniprocessor compiled
systems because it is assumed that a CPU will appear to be self-consistent,
and will order overlapping accesses correctly with respect to itself.
+However, see the subsection on "Virtual Machine Guests" below.
[!] Note that SMP memory barriers _must_ be used to control the ordering of
references to shared memory on SMP systems, though the use of locking instead
is sufficient.
Mandatory barriers should not be used to control SMP effects, since mandatory
-barriers unnecessarily impose overhead on UP systems. They may, however, be
-used to control MMIO effects on accesses through relaxed memory I/O windows.
-These are required even on non-SMP systems as they affect the order in which
-memory operations appear to a device by prohibiting both the compiler and the
-CPU from reordering them.
+barriers impose unnecessary overhead on both SMP and UP systems. They may,
+however, be used to control MMIO effects on accesses through relaxed memory I/O
+windows. These barriers are required even on non-SMP systems as they affect
+the order in which memory operations appear to a device by prohibiting both the
+compiler and the CPU from reordering them.
There are some more advanced barrier functions:
@@ -2948,6 +2949,23 @@ The Alpha defines the Linux kernel's memory barrier model.
See the subsection on "Cache Coherency" above.
+VIRTUAL MACHINE GUESTS
+-------------------
+
+Guests running within virtual machines might be affected by SMP effects even if
+the guest itself is compiled without SMP support. This is an artifact of
+interfacing with an SMP host while running an UP kernel. Using mandatory
+barriers for this use-case would be possible but is often suboptimal.
+
+To handle this case optimally, low-level virt_mb() etc macros are available.
+These have the same effect as smp_mb() etc when SMP is enabled, but generate
+identical code for SMP and non-SMP systems. For example, virtual machine guests
+should use virt_mb() rather than smp_mb() when synchronizing against a
+(possibly SMP) host.
+
+These are equivalent to smp_mb() etc counterparts in all other respects,
+in particular, they do not control MMIO effects: to control
+MMIO effects, use mandatory barriers.
============
EXAMPLE USES
--
MST
^ permalink raw reply related
* [PATCH v3 27/41] x86: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, Ingo Molnar,
xen-devel, Ingo Molnar, Borislav Petkov, linux-xtensa,
user-mode-linux-devel, Stefano Stabellini, adi-buildroot-devel,
Andy Lutomirski, Thomas Gleixner, linux-metag, linux-arm-kernel,
Andrew Cooper, Joe Perches
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for x86,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/x86/include/asm/barrier.h | 31 ++++++++++++-------------------
1 file changed, 12 insertions(+), 19 deletions(-)
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index cc4c2a7..a584e1c 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -31,17 +31,10 @@
#endif
#define dma_wmb() barrier()
-#ifdef CONFIG_SMP
-#define smp_mb() mb()
-#define smp_rmb() dma_rmb()
-#define smp_wmb() barrier()
-#define smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
-#else /* !SMP */
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
-#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
-#endif /* SMP */
+#define __smp_mb() mb()
+#define __smp_rmb() dma_rmb()
+#define __smp_wmb() barrier()
+#define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
#if defined(CONFIG_X86_PPRO_FENCE)
@@ -50,31 +43,31 @@
* model and we should fall back to full barriers.
*/
-#define smp_store_release(p, v) \
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
- smp_mb(); \
+ __smp_mb(); \
WRITE_ONCE(*p, v); \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
- smp_mb(); \
+ __smp_mb(); \
___p1; \
})
#else /* regular x86 TSO memory ordering */
-#define smp_store_release(p, v) \
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
@@ -85,8 +78,8 @@ do { \
#endif
/* Atomic operations are already serializing on x86 */
-#define smp_mb__before_atomic() barrier()
-#define smp_mb__after_atomic() barrier()
+#define __smp_mb__before_atomic() barrier()
+#define __smp_mb__after_atomic() barrier()
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 26/41] xtensa: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
Max Filippov, H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Chris Zankel, Andrew Cooper,
Joe Perches, linuxppc-dev
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for xtensa,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/xtensa/include/asm/barrier.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/xtensa/include/asm/barrier.h b/arch/xtensa/include/asm/barrier.h
index 5b88774..956596e 100644
--- a/arch/xtensa/include/asm/barrier.h
+++ b/arch/xtensa/include/asm/barrier.h
@@ -13,8 +13,8 @@
#define rmb() barrier()
#define wmb() mb()
-#define smp_mb__before_atomic() barrier()
-#define smp_mb__after_atomic() barrier()
+#define __smp_mb__before_atomic() barrier()
+#define __smp_mb__after_atomic() barrier()
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 25/41] tile: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:20 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
Chris Metcalf, H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller <davem>
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for tile,
for use by virtualization.
Some smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Note: for 32 bit, keep smp_mb__after_atomic around since it's faster
than the generic implementation.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/tile/include/asm/barrier.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/tile/include/asm/barrier.h b/arch/tile/include/asm/barrier.h
index 96a42ae..d552228 100644
--- a/arch/tile/include/asm/barrier.h
+++ b/arch/tile/include/asm/barrier.h
@@ -79,11 +79,12 @@ mb_incoherent(void)
* But after the word is updated, the routine issues an "mf" before returning,
* and since it's a function call, we don't even need a compiler barrier.
*/
-#define smp_mb__before_atomic() smp_mb()
-#define smp_mb__after_atomic() do { } while (0)
+#define __smp_mb__before_atomic() __smp_mb()
+#define __smp_mb__after_atomic() do { } while (0)
+#define smp_mb__after_atomic() __smp_mb__after_atomic()
#else /* 64 bit */
-#define smp_mb__before_atomic() smp_mb()
-#define smp_mb__after_atomic() smp_mb()
+#define __smp_mb__before_atomic() __smp_mb()
+#define __smp_mb__after_atomic() __smp_mb()
#endif
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 24/41] sparc: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for sparc,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
---
arch/sparc/include/asm/barrier_64.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/sparc/include/asm/barrier_64.h b/arch/sparc/include/asm/barrier_64.h
index 26c3f72..c9f6ee6 100644
--- a/arch/sparc/include/asm/barrier_64.h
+++ b/arch/sparc/include/asm/barrier_64.h
@@ -37,14 +37,14 @@ do { __asm__ __volatile__("ba,pt %%xcc, 1f\n\t" \
#define rmb() __asm__ __volatile__("":::"memory")
#define wmb() __asm__ __volatile__("":::"memory")
-#define smp_store_release(p, v) \
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
@@ -52,8 +52,8 @@ do { \
___p1; \
})
-#define smp_mb__before_atomic() barrier()
-#define smp_mb__after_atomic() barrier()
+#define __smp_mb__before_atomic() barrier()
+#define __smp_mb__after_atomic() barrier()
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 23/41] sh: define __smp_xxx, fix smp_store_mb for !SMP
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
sh variant of smp_store_mb() calls xchg() on !SMP which is stronger than
implied by both the name and the documentation.
define __smp_store_mb instead: code in asm-generic/barrier.h
will then define smp_store_mb correctly depending on
CONFIG_SMP.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/sh/include/asm/barrier.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/sh/include/asm/barrier.h b/arch/sh/include/asm/barrier.h
index bf91037..f887c64 100644
--- a/arch/sh/include/asm/barrier.h
+++ b/arch/sh/include/asm/barrier.h
@@ -32,7 +32,8 @@
#define ctrl_barrier() __asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop")
#endif
-#define smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
+#define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
+#define smp_store_mb(var, value) __smp_store_mb(var, value)
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 22/41] s390: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, Heiko Carstens,
virtualization, H. Peter Anvin, sparclinux, Ingo Molnar,
linux-arch, linux-s390, Davidlohr Bueso, Russell King - ARM Linux,
Arnd Bergmann, x86, Christian Borntraeger, xen-devel, Ingo Molnar,
linux-xtensa, user-mode-linux-devel, Stefano Stabellini,
adi-buildroot-devel, Martin Schwidefsky, Thomas Gleixner,
linux-metag
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for s390,
for use by virtualization.
Some smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Note: smp_mb, smp_rmb and smp_wmb are defined as full barriers
unconditionally on this architecture.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/include/asm/barrier.h | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index c358c31..fbd25b2 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -26,18 +26,21 @@
#define wmb() barrier()
#define dma_rmb() mb()
#define dma_wmb() mb()
-#define smp_mb() mb()
-#define smp_rmb() rmb()
-#define smp_wmb() wmb()
-
-#define smp_store_release(p, v) \
+#define __smp_mb() mb()
+#define __smp_rmb() rmb()
+#define __smp_wmb() wmb()
+#define smp_mb() __smp_mb()
+#define smp_rmb() __smp_rmb()
+#define smp_wmb() __smp_wmb()
+
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
--
MST
^ permalink raw reply related
* [PATCH v3 21/41] mips: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, Davidlohr Bueso, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Ralf Baechle,
Joe Perches <jo>
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for mips,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Note: the only exception is smp_mb__before_llsc which is mips-specific.
We define both the __smp_mb__before_llsc variant (for use in
asm/barriers.h) and smp_mb__before_llsc (for use elsewhere on this
architecture).
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/mips/include/asm/barrier.h | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/arch/mips/include/asm/barrier.h b/arch/mips/include/asm/barrier.h
index 3eac4b9..d296633 100644
--- a/arch/mips/include/asm/barrier.h
+++ b/arch/mips/include/asm/barrier.h
@@ -85,20 +85,20 @@
#define wmb() fast_wmb()
#define rmb() fast_rmb()
-#if defined(CONFIG_WEAK_ORDERING) && defined(CONFIG_SMP)
+#if defined(CONFIG_WEAK_ORDERING)
# ifdef CONFIG_CPU_CAVIUM_OCTEON
-# define smp_mb() __sync()
-# define smp_rmb() barrier()
-# define smp_wmb() __syncw()
+# define __smp_mb() __sync()
+# define __smp_rmb() barrier()
+# define __smp_wmb() __syncw()
# else
-# define smp_mb() __asm__ __volatile__("sync" : : :"memory")
-# define smp_rmb() __asm__ __volatile__("sync" : : :"memory")
-# define smp_wmb() __asm__ __volatile__("sync" : : :"memory")
+# define __smp_mb() __asm__ __volatile__("sync" : : :"memory")
+# define __smp_rmb() __asm__ __volatile__("sync" : : :"memory")
+# define __smp_wmb() __asm__ __volatile__("sync" : : :"memory")
# endif
#else
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
+#define __smp_mb() barrier()
+#define __smp_rmb() barrier()
+#define __smp_wmb() barrier()
#endif
#if defined(CONFIG_WEAK_REORDERING_BEYOND_LLSC) && defined(CONFIG_SMP)
@@ -111,6 +111,7 @@
#ifdef CONFIG_CPU_CAVIUM_OCTEON
#define smp_mb__before_llsc() smp_wmb()
+#define __smp_mb__before_llsc() __smp_wmb()
/* Cause previous writes to become visible on all CPUs as soon as possible */
#define nudge_writes() __asm__ __volatile__(".set push\n\t" \
".set arch=octeon\n\t" \
@@ -118,11 +119,12 @@
".set pop" : : : "memory")
#else
#define smp_mb__before_llsc() smp_llsc_mb()
+#define __smp_mb__before_llsc() smp_llsc_mb()
#define nudge_writes() mb()
#endif
-#define smp_mb__before_atomic() smp_mb__before_llsc()
-#define smp_mb__after_atomic() smp_llsc_mb()
+#define __smp_mb__before_atomic() __smp_mb__before_llsc()
+#define __smp_mb__after_atomic() smp_llsc_mb()
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 20/41] metag: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, Davidlohr Bueso, x86,
xen-devel, Ingo Molnar, linux-xtensa, James Hogan,
user-mode-linux-devel, Stefano Stabellini, adi-buildroot-devel,
Thomas Gleixner, linux-metag, linux-arm-kernel, Andrew Cooper
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for metag,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Note: as __smp_XX macros should not depend on CONFIG_SMP, they can not
use the existing fence() macro since that is defined differently between
SMP and !SMP. For this reason, this patch introduces a wrapper
metag_fence() that doesn't depend on CONFIG_SMP.
fence() is then defined using that, depending on CONFIG_SMP.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/metag/include/asm/barrier.h | 32 +++++++++++++++-----------------
1 file changed, 15 insertions(+), 17 deletions(-)
diff --git a/arch/metag/include/asm/barrier.h b/arch/metag/include/asm/barrier.h
index b5b778b..84880c9 100644
--- a/arch/metag/include/asm/barrier.h
+++ b/arch/metag/include/asm/barrier.h
@@ -44,13 +44,6 @@ static inline void wr_fence(void)
#define rmb() barrier()
#define wmb() mb()
-#ifndef CONFIG_SMP
-#define fence() do { } while (0)
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
-#else
-
#ifdef CONFIG_METAG_SMP_WRITE_REORDERING
/*
* Write to the atomic memory unlock system event register (command 0). This is
@@ -60,26 +53,31 @@ static inline void wr_fence(void)
* incoherence). It is therefore ineffective if used after and on the same
* thread as a write.
*/
-static inline void fence(void)
+static inline void metag_fence(void)
{
volatile int *flushptr = (volatile int *) LINSYSEVENT_WR_ATOMIC_UNLOCK;
barrier();
*flushptr = 0;
barrier();
}
-#define smp_mb() fence()
-#define smp_rmb() fence()
-#define smp_wmb() barrier()
+#define __smp_mb() metag_fence()
+#define __smp_rmb() metag_fence()
+#define __smp_wmb() barrier()
#else
-#define fence() do { } while (0)
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
+#define metag_fence() do { } while (0)
+#define __smp_mb() barrier()
+#define __smp_rmb() barrier()
+#define __smp_wmb() barrier()
#endif
+
+#ifdef CONFIG_SMP
+#define fence() metag_fence()
+#else
+#define fence() do { } while (0)
#endif
-#define smp_mb__before_atomic() barrier()
-#define smp_mb__after_atomic() barrier()
+#define __smp_mb__before_atomic() barrier()
+#define __smp_mb__after_atomic() barrier()
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 19/41] ia64: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Davidlohr Bueso, Russell King - ARM Linux, Arnd Bergmann, x86,
xen-devel, Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Tony Luck, Andrew Cooper,
Fenghua Yu <fengh>
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for ia64,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
This reduces the amount of arch-specific boiler-plate code.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/ia64/include/asm/barrier.h | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/arch/ia64/include/asm/barrier.h b/arch/ia64/include/asm/barrier.h
index 2f93348..588f161 100644
--- a/arch/ia64/include/asm/barrier.h
+++ b/arch/ia64/include/asm/barrier.h
@@ -42,28 +42,24 @@
#define dma_rmb() mb()
#define dma_wmb() mb()
-#ifdef CONFIG_SMP
-# define smp_mb() mb()
-#else
-# define smp_mb() barrier()
-#endif
+# define __smp_mb() mb()
-#define smp_mb__before_atomic() barrier()
-#define smp_mb__after_atomic() barrier()
+#define __smp_mb__before_atomic() barrier()
+#define __smp_mb__after_atomic() barrier()
/*
* IA64 GCC turns volatile stores into st.rel and volatile loads into ld.acq no
* need for asm trickery!
*/
-#define smp_store_release(p, v) \
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
--
MST
^ permalink raw reply related
* [PATCH v3 18/41] blackfin: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:19 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for blackfin,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/blackfin/include/asm/barrier.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/blackfin/include/asm/barrier.h b/arch/blackfin/include/asm/barrier.h
index dfb66fe..7cca51c 100644
--- a/arch/blackfin/include/asm/barrier.h
+++ b/arch/blackfin/include/asm/barrier.h
@@ -78,8 +78,8 @@
#endif /* !CONFIG_SMP */
-#define smp_mb__before_atomic() barrier()
-#define smp_mb__after_atomic() barrier()
+#define __smp_mb__before_atomic() barrier()
+#define __smp_mb__after_atomic() barrier()
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 17/41] arm: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, Richard Woodruff,
user-mode-linux-devel, Stefano Stabellini, adi-buildroot-devel,
Russell King, Thomas Gleixner, linux-metag, linux-arm-kernel,
Andrew Cooper, Jo
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for arm,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
This reduces the amount of arch-specific boiler-plate code.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/include/asm/barrier.h | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/arch/arm/include/asm/barrier.h b/arch/arm/include/asm/barrier.h
index 31152e8..112cc1a 100644
--- a/arch/arm/include/asm/barrier.h
+++ b/arch/arm/include/asm/barrier.h
@@ -60,15 +60,9 @@ extern void arm_heavy_mb(void);
#define dma_wmb() barrier()
#endif
-#ifndef CONFIG_SMP
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
-#else
-#define smp_mb() dmb(ish)
-#define smp_rmb() smp_mb()
-#define smp_wmb() dmb(ishst)
-#endif
+#define __smp_mb() dmb(ish)
+#define __smp_rmb() __smp_mb()
+#define __smp_wmb() dmb(ishst)
#include <asm-generic/barrier.h>
--
MST
^ permalink raw reply related
* [PATCH v3 16/41] arm64: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, Catalin Marinas,
Will Deacon, virtualization, H. Peter Anvin, sparclinux,
Ingo Molnar, linux-arch, linux-s390, Russell King - ARM Linux,
Arnd Bergmann, x86, xen-devel, Ingo Molnar, linux-xtensa,
user-mode-linux-devel, Stefano Stabellini, Andre Przywara,
adi-buildroot-devel, Thomas Gleixner, linux-metag,
linux-arm-kernel, Andrew
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for arm64,
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
Note: arm64 does not support !SMP config,
so smp_xxx and __smp_xxx are always equivalent.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm64/include/asm/barrier.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 91a43f4..dae5c49 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -35,11 +35,11 @@
#define dma_rmb() dmb(oshld)
#define dma_wmb() dmb(oshst)
-#define smp_mb() dmb(ish)
-#define smp_rmb() dmb(ishld)
-#define smp_wmb() dmb(ishst)
+#define __smp_mb() dmb(ish)
+#define __smp_rmb() dmb(ishld)
+#define __smp_wmb() dmb(ishst)
-#define smp_store_release(p, v) \
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
switch (sizeof(*p)) { \
@@ -62,7 +62,7 @@ do { \
} \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
union { typeof(*p) __val; char __c[1]; } __u; \
compiletime_assert_atomic_type(*p); \
--
MST
^ permalink raw reply related
* [PATCH v3 15/41] powerpc: define __smp_xxx
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra,
Benjamin Herrenschmidt, virtualization, Paul Mackerras,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Davidlohr Bueso, Russell King - ARM Linux, Arnd Bergmann,
Michael Ellerman, x86, xen-devel, Ingo Molnar, Paul E. McKenney,
linux-xtensa, user-mode-linux-devel, Stefano Stabellini,
Boqun Feng, adi-buildroot-devel
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
This defines __smp_xxx barriers for powerpc
for use by virtualization.
smp_xxx barriers are removed as they are
defined correctly by asm-generic/barriers.h
This reduces the amount of arch-specific boiler-plate code.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
---
arch/powerpc/include/asm/barrier.h | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
index 980ad0c..c0deafc 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -44,19 +44,11 @@
#define dma_rmb() __lwsync()
#define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
-#ifdef CONFIG_SMP
-#define smp_lwsync() __lwsync()
+#define __smp_lwsync() __lwsync()
-#define smp_mb() mb()
-#define smp_rmb() __lwsync()
-#define smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
-#else
-#define smp_lwsync() barrier()
-
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
-#endif /* CONFIG_SMP */
+#define __smp_mb() mb()
+#define __smp_rmb() __lwsync()
+#define __smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
/*
* This is a barrier which prevents following instructions from being
@@ -67,18 +59,18 @@
#define data_barrier(x) \
asm volatile("twi 0,%0,0; isync" : : "r" (x) : "memory");
-#define smp_store_release(p, v) \
+#define __smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
- smp_lwsync(); \
+ __smp_lwsync(); \
WRITE_ONCE(*p, v); \
} while (0)
-#define smp_load_acquire(p) \
+#define __smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
- smp_lwsync(); \
+ __smp_lwsync(); \
___p1; \
})
--
MST
^ permalink raw reply related
* [PATCH v3 14/41] asm-generic: add __smp_xxx wrappers
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev, David Miller
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
On !SMP, most architectures define their
barriers as compiler barriers.
On SMP, most need an actual barrier.
Make it possible to remove the code duplication for
!SMP by defining low-level __smp_xxx barriers
which do not depend on the value of SMP, then
use them from asm-generic conditionally.
Besides reducing code duplication, these low level APIs will also be
useful for virtualization, where a barrier is sometimes needed even if
!SMP since we might be talking to another kernel on the same SMP system.
Both virtio and Xen drivers will benefit.
The smp_xxx variants should use __smp_XXX ones or barrier() depending on
SMP, identically for all architectures.
We keep ifndef guards around them for now - once/if all
architectures are converted to use the generic
code, we'll be able to remove these.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
include/asm-generic/barrier.h | 91 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 82 insertions(+), 9 deletions(-)
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 987b2e0..8752964 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -54,22 +54,38 @@
#define read_barrier_depends() do { } while (0)
#endif
+#ifndef __smp_mb
+#define __smp_mb() mb()
+#endif
+
+#ifndef __smp_rmb
+#define __smp_rmb() rmb()
+#endif
+
+#ifndef __smp_wmb
+#define __smp_wmb() wmb()
+#endif
+
+#ifndef __smp_read_barrier_depends
+#define __smp_read_barrier_depends() read_barrier_depends()
+#endif
+
#ifdef CONFIG_SMP
#ifndef smp_mb
-#define smp_mb() mb()
+#define smp_mb() __smp_mb()
#endif
#ifndef smp_rmb
-#define smp_rmb() rmb()
+#define smp_rmb() __smp_rmb()
#endif
#ifndef smp_wmb
-#define smp_wmb() wmb()
+#define smp_wmb() __smp_wmb()
#endif
#ifndef smp_read_barrier_depends
-#define smp_read_barrier_depends() read_barrier_depends()
+#define smp_read_barrier_depends() __smp_read_barrier_depends()
#endif
#else /* !CONFIG_SMP */
@@ -92,23 +108,78 @@
#endif /* CONFIG_SMP */
+#ifndef __smp_store_mb
+#define __smp_store_mb(var, value) do { WRITE_ONCE(var, value); __smp_mb(); } while (0)
+#endif
+
+#ifndef __smp_mb__before_atomic
+#define __smp_mb__before_atomic() __smp_mb()
+#endif
+
+#ifndef __smp_mb__after_atomic
+#define __smp_mb__after_atomic() __smp_mb()
+#endif
+
+#ifndef __smp_store_release
+#define __smp_store_release(p, v) \
+do { \
+ compiletime_assert_atomic_type(*p); \
+ __smp_mb(); \
+ WRITE_ONCE(*p, v); \
+} while (0)
+#endif
+
+#ifndef __smp_load_acquire
+#define __smp_load_acquire(p) \
+({ \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
+ compiletime_assert_atomic_type(*p); \
+ __smp_mb(); \
+ ___p1; \
+})
+#endif
+
+#ifdef CONFIG_SMP
+
+#ifndef smp_store_mb
+#define smp_store_mb(var, value) __smp_store_mb(var, value)
+#endif
+
+#ifndef smp_mb__before_atomic
+#define smp_mb__before_atomic() __smp_mb__before_atomic()
+#endif
+
+#ifndef smp_mb__after_atomic
+#define smp_mb__after_atomic() __smp_mb__after_atomic()
+#endif
+
+#ifndef smp_store_release
+#define smp_store_release(p, v) __smp_store_release(p, v)
+#endif
+
+#ifndef smp_load_acquire
+#define smp_load_acquire(p) __smp_load_acquire(p)
+#endif
+
+#else /* !CONFIG_SMP */
+
#ifndef smp_store_mb
-#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while (0)
+#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
#endif
#ifndef smp_mb__before_atomic
-#define smp_mb__before_atomic() smp_mb()
+#define smp_mb__before_atomic() barrier()
#endif
#ifndef smp_mb__after_atomic
-#define smp_mb__after_atomic() smp_mb()
+#define smp_mb__after_atomic() barrier()
#endif
#ifndef smp_store_release
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
- smp_mb(); \
+ barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
#endif
@@ -118,10 +189,12 @@ do { \
({ \
typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
- smp_mb(); \
+ barrier(); \
___p1; \
})
#endif
+#endif
+
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_GENERIC_BARRIER_H */
--
MST
^ permalink raw reply related
* [PATCH v3 13/41] x86: reuse asm-generic/barrier.h
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, Ingo Molnar,
xen-devel, Ingo Molnar, Borislav Petkov, linux-xtensa,
user-mode-linux-devel, Stefano Stabellini, adi-buildroot-devel,
Andy Lutomirski, Thomas Gleixner, linux-metag, linux-arm-kernel,
Andrew Cooper, Joe Perches
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
As on most architectures, on x86 read_barrier_depends and
smp_read_barrier_depends are empty. Drop the local definitions and pull
the generic ones from asm-generic/barrier.h instead: they are identical.
This is in preparation to refactoring this code area.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/x86/include/asm/barrier.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index 0681d25..cc4c2a7 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -43,9 +43,6 @@
#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
#endif /* SMP */
-#define read_barrier_depends() do { } while (0)
-#define smp_read_barrier_depends() do { } while (0)
-
#if defined(CONFIG_X86_PPRO_FENCE)
/*
@@ -91,4 +88,6 @@ do { \
#define smp_mb__before_atomic() barrier()
#define smp_mb__after_atomic() barrier()
+#include <asm-generic/barrier.h>
+
#endif /* _ASM_X86_BARRIER_H */
--
MST
^ permalink raw reply related
* [PATCH v3 12/41] x86/um: reuse asm-generic/barrier.h
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, user-mode-linux-user, linux-sh,
Peter Zijlstra, virtualization, H. Peter Anvin, sparclinux,
linux-arch, linux-s390, Russell King - ARM Linux, Arnd Bergmann,
Richard Weinberger, x86, Ingo Molnar, xen-devel, Ingo Molnar,
Borislav Petkov, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, Jeff Dike, adi-buildroot-devel,
Andy Lutomirski, Thomas Gleixner, linux-metag
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
On x86/um CONFIG_SMP is never defined. As a result, several macros
match the asm-generic variant exactly. Drop the local definitions and
pull in asm-generic/barrier.h instead.
This is in preparation to refactoring this code area.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Richard Weinberger <richard@nod.at>
---
arch/x86/um/asm/barrier.h | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/arch/x86/um/asm/barrier.h b/arch/x86/um/asm/barrier.h
index 755481f..174781a 100644
--- a/arch/x86/um/asm/barrier.h
+++ b/arch/x86/um/asm/barrier.h
@@ -36,13 +36,6 @@
#endif /* CONFIG_X86_PPRO_FENCE */
#define dma_wmb() barrier()
-#define smp_mb() barrier()
-#define smp_rmb() barrier()
-#define smp_wmb() barrier()
-
-#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
-
-#define read_barrier_depends() do { } while (0)
-#define smp_read_barrier_depends() do { } while (0)
+#include <asm-generic/barrier.h>
#endif
--
MST
^ permalink raw reply related
* [PATCH v3 11/41] mips: reuse asm-generic/barrier.h
From: Michael S. Tsirkin @ 2016-01-10 14:18 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Ralf Baechle,
Joe Perches, linuxppc-dev
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
On mips dma_rmb, dma_wmb, smp_store_mb, read_barrier_depends,
smp_read_barrier_depends, smp_store_release and smp_load_acquire match
the asm-generic variants exactly. Drop the local definitions and pull in
asm-generic/barrier.h instead.
This is in preparation to refactoring this code area.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/mips/include/asm/barrier.h | 25 ++-----------------------
1 file changed, 2 insertions(+), 23 deletions(-)
diff --git a/arch/mips/include/asm/barrier.h b/arch/mips/include/asm/barrier.h
index 752e0b8..3eac4b9 100644
--- a/arch/mips/include/asm/barrier.h
+++ b/arch/mips/include/asm/barrier.h
@@ -10,9 +10,6 @@
#include <asm/addrspace.h>
-#define read_barrier_depends() do { } while(0)
-#define smp_read_barrier_depends() do { } while(0)
-
#ifdef CONFIG_CPU_HAS_SYNC
#define __sync() \
__asm__ __volatile__( \
@@ -87,8 +84,6 @@
#define wmb() fast_wmb()
#define rmb() fast_rmb()
-#define dma_wmb() fast_wmb()
-#define dma_rmb() fast_rmb()
#if defined(CONFIG_WEAK_ORDERING) && defined(CONFIG_SMP)
# ifdef CONFIG_CPU_CAVIUM_OCTEON
@@ -112,9 +107,6 @@
#define __WEAK_LLSC_MB " \n"
#endif
-#define smp_store_mb(var, value) \
- do { WRITE_ONCE(var, value); smp_mb(); } while (0)
-
#define smp_llsc_mb() __asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
#ifdef CONFIG_CPU_CAVIUM_OCTEON
@@ -129,22 +121,9 @@
#define nudge_writes() mb()
#endif
-#define smp_store_release(p, v) \
-do { \
- compiletime_assert_atomic_type(*p); \
- smp_mb(); \
- WRITE_ONCE(*p, v); \
-} while (0)
-
-#define smp_load_acquire(p) \
-({ \
- typeof(*p) ___p1 = READ_ONCE(*p); \
- compiletime_assert_atomic_type(*p); \
- smp_mb(); \
- ___p1; \
-})
-
#define smp_mb__before_atomic() smp_mb__before_llsc()
#define smp_mb__after_atomic() smp_llsc_mb()
+#include <asm-generic/barrier.h>
+
#endif /* __ASM_BARRIER_H */
--
MST
^ permalink raw reply related
* [PATCH v3 10/41] metag: reuse asm-generic/barrier.h
From: Michael S. Tsirkin @ 2016-01-10 14:17 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, virtualization,
H. Peter Anvin, sparclinux, Ingo Molnar, linux-arch, linux-s390,
Russell King - ARM Linux, Arnd Bergmann, x86, xen-devel,
Ingo Molnar, linux-xtensa, James Hogan, user-mode-linux-devel,
Stefano Stabellini, adi-buildroot-devel, Thomas Gleixner,
linux-metag, linux-arm-kernel, Andrew Cooper, Joe Perches,
linuxppc-dev
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
On metag dma_rmb, dma_wmb, smp_store_mb, read_barrier_depends,
smp_read_barrier_depends, smp_store_release and smp_load_acquire match
the asm-generic variants exactly. Drop the local definitions and pull in
asm-generic/barrier.h instead.
This is in preparation to refactoring this code area.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/metag/include/asm/barrier.h | 25 ++-----------------------
1 file changed, 2 insertions(+), 23 deletions(-)
diff --git a/arch/metag/include/asm/barrier.h b/arch/metag/include/asm/barrier.h
index 172b7e5..b5b778b 100644
--- a/arch/metag/include/asm/barrier.h
+++ b/arch/metag/include/asm/barrier.h
@@ -44,9 +44,6 @@ static inline void wr_fence(void)
#define rmb() barrier()
#define wmb() mb()
-#define dma_rmb() rmb()
-#define dma_wmb() wmb()
-
#ifndef CONFIG_SMP
#define fence() do { } while (0)
#define smp_mb() barrier()
@@ -81,27 +78,9 @@ static inline void fence(void)
#endif
#endif
-#define read_barrier_depends() do { } while (0)
-#define smp_read_barrier_depends() do { } while (0)
-
-#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while (0)
-
-#define smp_store_release(p, v) \
-do { \
- compiletime_assert_atomic_type(*p); \
- smp_mb(); \
- WRITE_ONCE(*p, v); \
-} while (0)
-
-#define smp_load_acquire(p) \
-({ \
- typeof(*p) ___p1 = READ_ONCE(*p); \
- compiletime_assert_atomic_type(*p); \
- smp_mb(); \
- ___p1; \
-})
-
#define smp_mb__before_atomic() barrier()
#define smp_mb__after_atomic() barrier()
+#include <asm-generic/barrier.h>
+
#endif /* _ASM_METAG_BARRIER_H */
--
MST
^ permalink raw reply related
* [PATCH v3 09/41] arm64: reuse asm-generic/barrier.h
From: Michael S. Tsirkin @ 2016-01-10 14:17 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mips, linux-ia64, linux-sh, Peter Zijlstra, Catalin Marinas,
Will Deacon, virtualization, H. Peter Anvin, sparclinux,
Ingo Molnar, linux-arch, linux-s390, Russell King - ARM Linux,
Arnd Bergmann, x86, xen-devel, Ingo Molnar, linux-xtensa,
user-mode-linux-devel, Stefano Stabellini, Andre Przywara,
adi-buildroot-devel, Thomas Gleixner, linux-metag,
linux-arm-kernel, Andrew
In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com>
On arm64 nop, read_barrier_depends, smp_read_barrier_depends
smp_store_mb(), smp_mb__before_atomic and smp_mb__after_atomic match the
asm-generic variants exactly. Drop the local definitions and pull in
asm-generic/barrier.h instead.
This is in preparation to refactoring this code area.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm64/include/asm/barrier.h | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 9622eb4..91a43f4 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -91,14 +91,7 @@ do { \
__u.__val; \
})
-#define read_barrier_depends() do { } while(0)
-#define smp_read_barrier_depends() do { } while(0)
-
-#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while (0)
-#define nop() asm volatile("nop");
-
-#define smp_mb__before_atomic() smp_mb()
-#define smp_mb__after_atomic() smp_mb()
+#include <asm-generic/barrier.h>
#endif /* __ASSEMBLY__ */
--
MST
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