sctp: allow sctp_transmit_packet and others to use gfp

Currently sctp_sendmsg() triggers some calls that will allocate memory
with GFP_ATOMIC even when not necessary. In the case of
sctp_packet_transmit it will allocate a linear skb that will be used to
construct the packet and this may cause sends to fail due to ENOMEM more
often than anticipated specially with big MTUs.

This patch thus allows it to inherit gfp flags from upper calls so that
it can use GFP_KERNEL if it was triggered by a sctp_sendmsg call or
similar. All others, like retransmits or flushes started from BH, are
still allocated using GFP_ATOMIC.

In netperf tests this didn't result in any performance drawbacks when
memory is not too fragmented and made it trigger ENOMEM way less often.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index 487ef34bbd63..efc01743b9d6 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -201,7 +201,7 @@ struct sctp_chunk *sctp_make_cwr(const struct sctp_association *,
 struct sctp_chunk * sctp_make_datafrag_empty(struct sctp_association *,
 					const struct sctp_sndrcvinfo *sinfo,
 					int len, const __u8 flags,
-					__u16 ssn);
+					__u16 ssn, gfp_t gfp);
 struct sctp_chunk *sctp_make_ecne(const struct sctp_association *,
 				  const __u32);
 struct sctp_chunk *sctp_make_sack(const struct sctp_association *);