From a21d45726acacc963d8baddf74607d9b74e2b723 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 10 Apr 2012 20:30:48 +0000 Subject: tcp: avoid order-1 allocations on wifi and tx path Marc Merlin reported many order-1 allocations failures in TX path on its wireless setup, that dont make any sense with MTU=1500 network, and non SG capable hardware. After investigation, it turns out TCP uses sk_stream_alloc_skb() and used as a convention skb_tailroom(skb) to know how many bytes of data payload could be put in this skb (for non SG capable devices) Note : these skb used kmalloc-4096 (MTU=1500 + MAX_HEADER + sizeof(struct skb_shared_info) being above 2048) Later, mac80211 layer need to add some bytes at the tail of skb (IEEE80211_ENCRYPT_TAILROOM = 18 bytes) and since no more tailroom is available has to call pskb_expand_head() and request order-1 allocations. This patch changes sk_stream_alloc_skb() so that only sk->sk_prot->max_header bytes of headroom are reserved, and use a new skb field, avail_size to hold the data payload limit. This way, order-0 allocations done by TCP stack can leave more than 2 KB of tailroom and no more allocation is performed in mac80211 layer (or any layer needing some tailroom) avail_size is unioned with mark/dropcount, since mark will be set later in IP stack for output packets. Therefore, skb size is unchanged. Reported-by: Marc MERLIN Tested-by: Marc MERLIN Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/skbuff.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 33370271b8b..70a3f8d4911 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -481,6 +481,7 @@ struct sk_buff { union { __u32 mark; __u32 dropcount; + __u32 avail_size; }; sk_buff_data_t transport_header; @@ -1365,6 +1366,18 @@ static inline int skb_tailroom(const struct sk_buff *skb) return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail; } +/** + * skb_availroom - bytes at buffer end + * @skb: buffer to check + * + * Return the number of bytes of free space at the tail of an sk_buff + * allocated by sk_stream_alloc() + */ +static inline int skb_availroom(const struct sk_buff *skb) +{ + return skb_is_nonlinear(skb) ? 0 : skb->avail_size - skb->len; +} + /** * skb_reserve - adjust headroom * @skb: buffer to alter -- cgit v1.2.3-70-g09d2 From ca8f4fb21d08747013cce9cf1840aa5bfc31f2d8 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Mon, 9 Apr 2012 00:24:02 +0000 Subject: skbuff: struct ubuf_info callback type safety The skb struct ubuf_info callback gets passed struct ubuf_info itself, not the arg value as the field name and the function signature seem to imply. Rename the arg field to ctx to match usage, add documentation and change the callback argument type to make usage clear and to have compiler check correctness. Signed-off-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/vhost/net.c | 2 +- drivers/vhost/vhost.c | 5 ++--- drivers/vhost/vhost.h | 2 +- include/linux/skbuff.h | 7 ++++--- 4 files changed, 8 insertions(+), 8 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index f0da2c32fbd..1f21d2a1e52 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -238,7 +238,7 @@ static void handle_tx(struct vhost_net *net) vq->heads[vq->upend_idx].len = len; ubuf->callback = vhost_zerocopy_callback; - ubuf->arg = vq->ubufs; + ubuf->ctx = vq->ubufs; ubuf->desc = vq->upend_idx; msg.msg_control = ubuf; msg.msg_controllen = sizeof(ubuf); diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 947f00d8e09..51e4c1eeec4 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1598,10 +1598,9 @@ void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs) kfree(ubufs); } -void vhost_zerocopy_callback(void *arg) +void vhost_zerocopy_callback(struct ubuf_info *ubuf) { - struct ubuf_info *ubuf = arg; - struct vhost_ubuf_ref *ubufs = ubuf->arg; + struct vhost_ubuf_ref *ubufs = ubuf->ctx; struct vhost_virtqueue *vq = ubufs->vq; /* set len = 1 to mark this desc buffers done DMA */ diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 8dcf4cca6bf..8de1fd5b8ef 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -188,7 +188,7 @@ bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *); int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, unsigned int log_num, u64 len); -void vhost_zerocopy_callback(void *arg); +void vhost_zerocopy_callback(struct ubuf_info *); int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq); #define vq_err(vq, fmt, ...) do { \ diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 70a3f8d4911..775292a66fa 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -238,11 +238,12 @@ enum { /* * The callback notifies userspace to release buffers when skb DMA is done in * lower device, the skb last reference should be 0 when calling this. - * The desc is used to track userspace buffer index. + * The ctx field is used to track device context. + * The desc field is used to track userspace buffer index. */ struct ubuf_info { - void (*callback)(void *); - void *arg; + void (*callback)(struct ubuf_info *); + void *ctx; unsigned long desc; }; -- cgit v1.2.3-70-g09d2 From d961949660fa1c1b7eb0c3a3c157989c90f14e8e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 30 Apr 2012 21:29:16 +0000 Subject: net: fix two typos in skbuff.h fix kernel doc typos in function names Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/skbuff.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 775292a66fa..111f26b6e28 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1020,7 +1020,7 @@ static inline void skb_queue_splice(const struct sk_buff_head *list, } /** - * skb_queue_splice - join two skb lists and reinitialise the emptied list + * skb_queue_splice_init - join two skb lists and reinitialise the emptied list * @list: the new list to add * @head: the place to add it in the first list * @@ -1051,7 +1051,7 @@ static inline void skb_queue_splice_tail(const struct sk_buff_head *list, } /** - * skb_queue_splice_tail - join two skb lists and reinitialise the emptied list + * skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list * @list: the new list to add * @head: the place to add it in the first list * -- cgit v1.2.3-70-g09d2