From 5a1b26d7c629915446222ebe77d16567c98426ff Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Thu, 31 Dec 2015 12:09:13 +0200 Subject: lcoking/barriers, arch: Use smp barriers in smp_store_release() With commit b92b8b35a2e ("locking/arch: Rename set_mb() to smp_store_mb()") it was made clear that the context of this call (and thus set_mb) is strictly for CPU ordering, as opposed to IO. As such all archs should use the smp variant of mb(), respecting the semantics and saving a mandatory barrier on UP. Signed-off-by: Davidlohr Bueso Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Andrew Morton Cc: Benjamin Herrenschmidt Cc: Heiko Carstens Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tony Luck Cc: dave@stgolabs.net Link: http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar Reviewed-by: Paul E. McKenney --- include/asm-generic/barrier.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index b42afada1280..0f45f93ef692 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -93,7 +93,7 @@ #endif /* CONFIG_SMP */ #ifndef smp_store_mb -#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); mb(); } while (0) +#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while (0) #endif #ifndef smp_mb__before_atomic -- cgit v1.2.3-58-ga151 From 57f7c0370f386d5e0960e25d2c3ceb0b8e8c489d Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 14:10:52 +0200 Subject: asm-generic: guard smp_store_release/load_acquire Allow architectures to override smp_store_release and smp_load_acquire by guarding the defines in asm-generic/barrier.h with ifndef directives. This is in preparation to reusing asm-generic/barrier.h on architectures which have their own definition of these macros. Signed-off-by: Michael S. Tsirkin Acked-by: Arnd Bergmann Acked-by: Peter Zijlstra (Intel) --- include/asm-generic/barrier.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 0f45f93ef692..987b2e04ad5a 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -104,13 +104,16 @@ #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); \ @@ -118,6 +121,7 @@ do { \ smp_mb(); \ ___p1; \ }) +#endif #endif /* !__ASSEMBLY__ */ #endif /* __ASM_GENERIC_BARRIER_H */ -- cgit v1.2.3-58-ga151 From a9e4252a9b147043142282ebb65da94dcb951e2a Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 13:50:07 +0200 Subject: asm-generic: add __smp_xxx wrappers 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 Signed-off-by: Michael S. Tsirkin Acked-by: Arnd Bergmann Acked-by: Peter Zijlstra (Intel) --- include/asm-generic/barrier.h | 91 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 82 insertions(+), 9 deletions(-) (limited to 'include') diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 987b2e04ad5a..8752964f8ff7 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 */ -- cgit v1.2.3-58-ga151 From 6a65d26385bf487926a0616650927303058551e3 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 18:23:01 +0200 Subject: asm-generic: implement virt_xxx memory barriers 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 Signed-off-by: Michael S. Tsirkin Acked-by: Peter Zijlstra (Intel) --- Documentation/memory-barriers.txt | 28 +++++++++++++++++++++++----- include/asm-generic/barrier.h | 11 +++++++++++ 2 files changed, 34 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index aef9487303d0..8f4a93aae19f 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 diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 8752964f8ff7..1cceca146905 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 */ -- cgit v1.2.3-58-ga151 From d307fb16f788823b29aab9aa7e4821ac8a124b19 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 20 Dec 2015 13:52:10 +0200 Subject: Revert "virtio_ring: Update weak barriers to use dma_wmb/rmb" 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 Cc: Alexander Duyck Signed-off-by: Michael S. Tsirkin Acked-by: Peter Zijlstra (Intel) --- include/linux/virtio_ring.h | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index 8e50888a6d59..67e06fe18c03 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; -- cgit v1.2.3-58-ga151 From a65961272e1ebdb60804bbe2bb440481fcbd1c76 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 17:55:35 +0200 Subject: virtio_ring: update weak barriers to use virt_xxx 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 Cc: Alexander Duyck Signed-off-by: Michael S. Tsirkin Acked-by: Peter Zijlstra (Intel) --- include/linux/virtio_ring.h | 25 ++++--------------------- 1 file changed, 4 insertions(+), 21 deletions(-) (limited to 'include') diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index 67e06fe18c03..f3fa55bdd6ce 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; -- cgit v1.2.3-58-ga151 From 788e5b3a5da24cc8d93ce2f7c6508181cd7d7fb6 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 17 Dec 2015 12:20:39 +0200 Subject: virtio_ring: use virt_store_mb 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 Acked-by: Peter Zijlstra (Intel) --- drivers/virtio/virtio_ring.c | 15 +++++++++------ include/linux/virtio_ring.h | 11 +++++++++++ 2 files changed, 20 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index ee663c458b20..e12e385f7ac3 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; diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index f3fa55bdd6ce..a156e2b6ccfe 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; -- cgit v1.2.3-58-ga151 From 506b02eb1cf79838b76c6e3e43171cf960f01fc8 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 18:02:16 +0200 Subject: xen/io: use virt_xxx barriers include/xen/interface/io/ring.h uses full memory barriers to communicate with the other side. For guests compiled with CONFIG_SMP, smp_wmb and smp_mb would be sufficient, so mb() and wmb() here are only needed if a non-SMP guest runs on an SMP host. Switch to virt_xxx barriers which serve this exact purpose. Signed-off-by: Michael S. Tsirkin Acked-by: David Vrabel Acked-by: Peter Zijlstra (Intel) --- include/xen/interface/io/ring.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'include') diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 7dc685b4057d..21f4fbd55e48 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -208,12 +208,12 @@ struct __name##_back_ring { \ #define RING_PUSH_REQUESTS(_r) do { \ - wmb(); /* back sees requests /before/ updated producer index */ \ + virt_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = (_r)->req_prod_pvt; \ } while (0) #define RING_PUSH_RESPONSES(_r) do { \ - wmb(); /* front sees responses /before/ updated producer index */ \ + virt_wmb(); /* front sees responses /before/ updated producer index */ \ (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ } while (0) @@ -250,9 +250,9 @@ struct __name##_back_ring { \ #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ RING_IDX __old = (_r)->sring->req_prod; \ RING_IDX __new = (_r)->req_prod_pvt; \ - wmb(); /* back sees requests /before/ updated producer index */ \ + virt_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = __new; \ - mb(); /* back sees new requests /before/ we check req_event */ \ + virt_mb(); /* back sees new requests /before/ we check req_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -260,9 +260,9 @@ struct __name##_back_ring { \ #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ RING_IDX __old = (_r)->sring->rsp_prod; \ RING_IDX __new = (_r)->rsp_prod_pvt; \ - wmb(); /* front sees responses /before/ updated producer index */ \ + virt_wmb(); /* front sees responses /before/ updated producer index */ \ (_r)->sring->rsp_prod = __new; \ - mb(); /* front sees new responses /before/ we check rsp_event */ \ + virt_mb(); /* front sees new responses /before/ we check rsp_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -271,7 +271,7 @@ struct __name##_back_ring { \ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ if (_work_to_do) break; \ (_r)->sring->req_event = (_r)->req_cons + 1; \ - mb(); \ + virt_mb(); \ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ } while (0) @@ -279,7 +279,7 @@ struct __name##_back_ring { \ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ if (_work_to_do) break; \ (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ - mb(); \ + virt_mb(); \ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ } while (0) -- cgit v1.2.3-58-ga151 From f7ad26ff952b3ca2702d7da03aad0ab1f6c01d7c Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 17 Dec 2015 16:53:43 +0800 Subject: virtio: make find_vqs() checkpatch.pl-friendly checkpatch.pl wants arrays of strings declared as follows: static const char * const names[] = { "vq-1", "vq-2", "vq-3" }; Currently the find_vqs() function takes a const char *names[] argument so passing checkpatch.pl's const char * const names[] results in a compiler error due to losing the second const. This patch adjusts the find_vqs() prototype and updates all virtio transports. This makes it possible for virtio_balloon.c, virtio_input.c, virtgpu_kms.c, and virtio_rpmsg_bus.c to use the checkpatch.pl-friendly type. Signed-off-by: Stefan Hajnoczi Signed-off-by: Michael S. Tsirkin Acked-by: Bjorn Andersson --- drivers/gpu/drm/virtio/virtgpu_kms.c | 2 +- drivers/misc/mic/card/mic_virtio.c | 2 +- drivers/remoteproc/remoteproc_virtio.c | 2 +- drivers/rpmsg/virtio_rpmsg_bus.c | 2 +- drivers/s390/virtio/kvm_virtio.c | 2 +- drivers/s390/virtio/virtio_ccw.c | 2 +- drivers/virtio/virtio_balloon.c | 2 +- drivers/virtio/virtio_input.c | 2 +- drivers/virtio/virtio_mmio.c | 2 +- drivers/virtio/virtio_pci_common.c | 4 ++-- drivers/virtio/virtio_pci_common.h | 2 +- drivers/virtio/virtio_pci_modern.c | 2 +- include/linux/virtio_config.h | 2 +- 13 files changed, 14 insertions(+), 14 deletions(-) (limited to 'include') diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c index 06496a128162..4150873d432e 100644 --- a/drivers/gpu/drm/virtio/virtgpu_kms.c +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c @@ -130,7 +130,7 @@ int virtio_gpu_driver_load(struct drm_device *dev, unsigned long flags) static vq_callback_t *callbacks[] = { virtio_gpu_ctrl_ack, virtio_gpu_cursor_ack }; - static const char *names[] = { "control", "cursor" }; + static const char * const names[] = { "control", "cursor" }; struct virtio_gpu_device *vgdev; /* this will expand later */ diff --git a/drivers/misc/mic/card/mic_virtio.c b/drivers/misc/mic/card/mic_virtio.c index e486a0c26267..f6ed57d3125c 100644 --- a/drivers/misc/mic/card/mic_virtio.c +++ b/drivers/misc/mic/card/mic_virtio.c @@ -311,7 +311,7 @@ unmap: static int mic_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { struct mic_vdev *mvdev = to_micvdev(vdev); struct mic_device_ctrl __iomem *dc = mvdev->dc; diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c index e1a10232a943..e44872fb9e5e 100644 --- a/drivers/remoteproc/remoteproc_virtio.c +++ b/drivers/remoteproc/remoteproc_virtio.c @@ -147,7 +147,7 @@ static void rproc_virtio_del_vqs(struct virtio_device *vdev) static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { struct rproc *rproc = vdev_to_rproc(vdev); int i, ret; diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c index 73354ee27877..1fcd27c1f183 100644 --- a/drivers/rpmsg/virtio_rpmsg_bus.c +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -945,7 +945,7 @@ static void rpmsg_ns_cb(struct rpmsg_channel *rpdev, void *data, int len, static int rpmsg_probe(struct virtio_device *vdev) { vq_callback_t *vq_cbs[] = { rpmsg_recv_done, rpmsg_xmit_done }; - const char *names[] = { "input", "output" }; + static const char * const names[] = { "input", "output" }; struct virtqueue *vqs[2]; struct virtproc_info *vrp; void *bufs_va; diff --git a/drivers/s390/virtio/kvm_virtio.c b/drivers/s390/virtio/kvm_virtio.c index 53fb975c404b..1d060fd293a3 100644 --- a/drivers/s390/virtio/kvm_virtio.c +++ b/drivers/s390/virtio/kvm_virtio.c @@ -255,7 +255,7 @@ static void kvm_del_vqs(struct virtio_device *vdev) static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { struct kvm_device *kdev = to_kvmdev(vdev); int i; diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 1b831598df7c..bf2d1300a957 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -635,7 +635,7 @@ out: static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { struct virtio_ccw_device *vcdev = to_vc_device(vdev); unsigned long *indicatorp = NULL; diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 7d3e5d0e9aa4..0c3691f46575 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -388,7 +388,7 @@ static int init_vqs(struct virtio_balloon *vb) { struct virtqueue *vqs[3]; vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; - const char *names[] = { "inflate", "deflate", "stats" }; + static const char * const names[] = { "inflate", "deflate", "stats" }; int err, nvqs; /* diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c index c96944b59856..350a2a5a49db 100644 --- a/drivers/virtio/virtio_input.c +++ b/drivers/virtio/virtio_input.c @@ -170,7 +170,7 @@ static int virtinput_init_vqs(struct virtio_input *vi) struct virtqueue *vqs[2]; vq_callback_t *cbs[] = { virtinput_recv_events, virtinput_recv_status }; - static const char *names[] = { "events", "status" }; + static const char * const names[] = { "events", "status" }; int err; err = vi->vdev->config->find_vqs(vi->vdev, 2, vqs, cbs, names); diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c index f499d9da7237..745c6ee1bb3e 100644 --- a/drivers/virtio/virtio_mmio.c +++ b/drivers/virtio/virtio_mmio.c @@ -482,7 +482,7 @@ error_available: static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); unsigned int irq = platform_get_irq(vm_dev->pdev, 0); diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c index 78f804af6c20..36205c27c4d0 100644 --- a/drivers/virtio/virtio_pci_common.c +++ b/drivers/virtio/virtio_pci_common.c @@ -296,7 +296,7 @@ void vp_del_vqs(struct virtio_device *vdev) static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[], + const char * const names[], bool use_msix, bool per_vq_vectors) { @@ -376,7 +376,7 @@ error_find: int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { int err; diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h index b976d968e793..2cc252270b2d 100644 --- a/drivers/virtio/virtio_pci_common.h +++ b/drivers/virtio/virtio_pci_common.h @@ -139,7 +139,7 @@ void vp_del_vqs(struct virtio_device *vdev); int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]); + const char * const names[]); const char *vp_bus_name(struct virtio_device *vdev); /* Setup the affinity for a virtqueue: diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c index 8e5cf194cc0b..c0c11fad4611 100644 --- a/drivers/virtio/virtio_pci_modern.c +++ b/drivers/virtio/virtio_pci_modern.c @@ -418,7 +418,7 @@ err_new_queue: static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]) + const char * const names[]) { struct virtio_pci_device *vp_dev = to_vp_device(vdev); struct virtqueue *vq; diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index e5ce8ab0b8b0..6e6cb0c9d7cb 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -70,7 +70,7 @@ struct virtio_config_ops { int (*find_vqs)(struct virtio_device *, unsigned nvqs, struct virtqueue *vqs[], vq_callback_t *callbacks[], - const char *names[]); + const char * const names[]); void (*del_vqs)(struct virtio_device *); u64 (*get_features)(struct virtio_device *vdev); int (*finalize_features)(struct virtio_device *vdev); -- cgit v1.2.3-58-ga151