[PATCH net-next V3 3/6] ptr_ring: support resizing multiple queues

Jason Wang
2016-06-30T04:03:29Z

From: "Michael S. Tsirkin" <mst@redhat.com>

Sometimes, we need support resizing multiple queues at once. This is
because it was not easy to recover to recover from a partial failure
of multiple queues resizing.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
include/linux/ptr_ring.h | 71 +++++++++++++++++++++++++++++++++++-----
tools/virtio/ringtest/ptr_ring.c | 5 +++
2 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index d78b8b8..2052011 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -349,20 +349,14 @@ static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
return 0;
}

-static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
- void (*destroy)(void *))
+static inline void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
+ int size, gfp_t gfp,
+ void (*destroy)(void *))
{
- unsigned long flags;
int producer = 0;
- void **queue = __ptr_ring_init_queue_alloc(size, gfp);
void **old;
void *ptr;

- if (!queue)
- return -ENOMEM;
-
- spin_lock_irqsave(&(r)->producer_lock, flags);
-
while ((ptr = ptr_ring_consume(r)))
if (producer < size)
queue[producer++] = ptr;
@@ -375,6 +369,23 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
old = r->queue;
r->queue = queue;

+ return old;
+}
+
+static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
+ void (*destroy)(void *))
+{
+ unsigned long flags;
+ void **queue = __ptr_ring_init_queue_alloc(size, gfp);
+ void **old;
+
+ if (!queue)
+ return -ENOMEM;
+
+ spin_lock_irqsave(&(r)->producer_lock, flags);
+
+ old = __ptr_ring_swap_queue(r, queue, size, gfp, destroy);
+
spin_unlock_irqrestore(&(r)->producer_lock, flags);

kfree(old);
@@ -382,6 +393,48 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
return 0;
}

+static inline int ptr_ring_resize_multiple(struct ptr_ring **rings, int nrings,
+ int size,
+ gfp_t gfp, void (*destroy)(void *))
+{
+ unsigned long flags;
+ void ***queues;
+ int i;
+
+ queues = kmalloc(nrings * sizeof *queues, gfp);
+ if (!queues)
+ goto noqueues;
+
+ for (i = 0; i < nrings; ++i) {
+ queues[i] = __ptr_ring_init_queue_alloc(size, gfp);
+ if (!queues[i])
+ goto nomem;
+ }
+
+ for (i = 0; i < nrings; ++i) {
+ spin_lock_irqsave(&(rings[i])->producer_lock, flags);
+ queues[i] = __ptr_ring_swap_queue(rings[i], queues[i],
+ size, gfp, destroy);
+ spin_unlock_irqrestore(&(rings[i])->producer_lock, flags);
+ }
+
+ for (i = 0; i < nrings; ++i)
+ kfree(queues[i]);
+
+ kfree(queues);
+
+ return 0;
+
+nomem:
+ while (--i >= 0)
+ kfree(queues[i]);
+
+ kfree(queues);
+
+noqueues:
+ return -ENOMEM;
+}
+
static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
{
void *ptr;
diff --git a/tools/virtio/ringtest/ptr_ring.c b/tools/virtio/ringtest/ptr_ring.c
index 74abd74..68e4f9f 100644
--- a/tools/virtio/ringtest/ptr_ring.c
+++ b/tools/virtio/ringtest/ptr_ring.c
@@ -17,6 +17,11 @@
typedef pthread_spinlock_t spinlock_t;

typedef int gfp_t;
+static void *kmalloc(unsigned size, gfp_t gfp)
+{
+ return memalign(64, size);
+}
+
static void *kzalloc(unsigned size, gfp_t gfp)
{
void *p = memalign(64, size);
--
2.7.4