From: Jason Wang <jasowang@redhat.com>
To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com
Cc: Jason Wang <jasowang@redhat.com>
Subject: [PATCH net-next V3 1/9] ptr_ring: add ptr_ring_unconsume
Date: Wed, 10 May 2017 10:37:53 +0800 [thread overview]
Message-ID: <1494383881-6811-2-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1494383881-6811-1-git-send-email-jasowang@redhat.com>
From: "Michael S. Tsirkin" <mst@redhat.com>
Applications that consume a batch of entries in one go
can benefit from ability to return some of them back
into the ring.
Add an API for that - assuming there's space. If there's no space
naturally can't do this and have to drop entries, but this implies ring
is full so we'd likely drop some anyway.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
include/linux/ptr_ring.h | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 6c70444..5476f68 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -359,6 +359,61 @@ static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
return 0;
}
+/*
+ * Return entries into ring. Destroy entries that don't fit.
+ *
+ * Note: this is expected to be a rare slow path operation.
+ *
+ * Note: producer lock is nested within consumer lock, so if you
+ * resize you must make sure all uses nest correctly.
+ * In particular if you consume ring in interrupt or BH context, you must
+ * disable interrupts/BH when doing so.
+ */
+static inline void ptr_ring_unconsume(struct ptr_ring *r, void **batch, int n,
+ void (*destroy)(void *))
+{
+ unsigned long flags;
+ int head;
+
+ spin_lock_irqsave(&r->consumer_lock, flags);
+ spin_lock(&r->producer_lock);
+
+ if (!r->size)
+ goto done;
+
+ /*
+ * Clean out buffered entries (for simplicity). This way following code
+ * can test entries for NULL and if not assume they are valid.
+ */
+ head = r->consumer_head - 1;
+ while (likely(head >= r->consumer_tail))
+ r->queue[head--] = NULL;
+ r->consumer_tail = r->consumer_head;
+
+ /*
+ * Go over entries in batch, start moving head back and copy entries.
+ * Stop when we run into previously unconsumed entries.
+ */
+ while (n) {
+ head = r->consumer_head - 1;
+ if (head < 0)
+ head = r->size - 1;
+ if (r->queue[head]) {
+ /* This batch entry will have to be destroyed. */
+ goto done;
+ }
+ r->queue[head] = batch[--n];
+ r->consumer_tail = r->consumer_head = head;
+ }
+
+done:
+ /* Destroy all entries left in the batch. */
+ while (n)
+ destroy(batch[--n]);
+ spin_unlock(&r->producer_lock);
+ spin_unlock_irqrestore(&r->consumer_lock, flags);
+}
+
static inline void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
int size, gfp_t gfp,
void (*destroy)(void *))
--
2.7.4
next prev parent reply other threads:[~2017-05-10 2:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-10 2:37 [PATCH net-next V3 0/9] vhost_net rx batch dequeuing Jason Wang
2017-05-10 2:37 ` Jason Wang [this message]
2017-05-10 2:37 ` [PATCH net-next V3 2/9] skb_array: introduce skb_array_unconsume Jason Wang
2017-05-10 2:37 ` [PATCH net-next V3 3/9] ptr_ring: introduce batch dequeuing Jason Wang
2017-05-10 2:37 ` [PATCH net-next V3 4/9] skb_array: " Jason Wang
2017-05-10 2:37 ` [PATCH net-next V3 5/9] tun: export skb_array Jason Wang
2017-05-10 2:37 ` [PATCH net-next V3 6/9] tap: " Jason Wang
2017-05-10 2:37 ` [PATCH net-next V3 7/9] tun: support receiving skb through msg_control Jason Wang
2017-05-10 2:38 ` [PATCH net-next V3 8/9] tap: support receiving skb from msg_control Jason Wang
2017-05-10 2:38 ` [PATCH net-next V3 9/9] vhost_net: try batch dequing from skb array Jason Wang
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