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| author | Daniel Borkmann <dborkman@redhat.com> | 2014-01-15 16:25:35 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-01-16 16:17:11 -0800 |
| commit | 87a2fd286adf35a87cf6cb30fa80a0726eb74f76 (patch) | |
| tree | 0510e7dda15901deb3f4432f41c48539f40baf8c /net/packet | |
| parent | 902fefb82ef72a50c78cb4a20cc954b037a98d1c (diff) | |
| download | linux-87a2fd286adf35a87cf6cb30fa80a0726eb74f76.tar.gz linux-87a2fd286adf35a87cf6cb30fa80a0726eb74f76.tar.bz2 linux-87a2fd286adf35a87cf6cb30fa80a0726eb74f76.zip | |
packet: don't unconditionally schedule() in case of MSG_DONTWAIT
In tpacket_snd(), when we've discovered a first frame that is
not in status TP_STATUS_SEND_REQUEST, and return a NULL buffer,
we exit the send routine in case of MSG_DONTWAIT, since we've
finished traversing the mmaped send ring buffer and don't care
about pending frames.
While doing so, we still unconditionally call an expensive
schedule() in the packet_current_frame() "error" path, which
is unnecessary in this case since it's enough to just quit
the function.
Also, in case MSG_DONTWAIT is not set, we should rather test
for need_resched() first and do schedule() only if necessary
since meanwhile pending frames could already have finished
processing and called skb destructor.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
| -rw-r--r-- | net/packet/af_packet.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 85bb38cb56fd..d5495d87f399 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2156,6 +2156,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) int err, reserve = 0; void *ph; struct sockaddr_ll *saddr = (struct sockaddr_ll *)msg->msg_name; + bool need_wait = !(msg->msg_flags & MSG_DONTWAIT); int tp_len, size_max; unsigned char *addr; int len_sum = 0; @@ -2198,10 +2199,10 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) do { ph = packet_current_frame(po, &po->tx_ring, - TP_STATUS_SEND_REQUEST); - + TP_STATUS_SEND_REQUEST); if (unlikely(ph == NULL)) { - schedule(); + if (need_wait && need_resched()) + schedule(); continue; } @@ -2255,10 +2256,8 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) } packet_increment_head(&po->tx_ring); len_sum += tp_len; - } while (likely((ph != NULL) || - ((!(msg->msg_flags & MSG_DONTWAIT)) && - (atomic_read(&po->tx_ring.pending)))) - ); + } while (likely((ph != NULL) || (need_wait && + atomic_read(&po->tx_ring.pending)))); err = len_sum; goto out_put; |