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, 12 insertions, 11 deletions

diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index b5327bb77458..3c22c41a2bc2 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -1019,13 +1019,13 @@ static void sctp_cmd_t1_timer_update(struct sctp_association *asoc,
  * encouraged for small fragments.
  */
 static int sctp_cmd_send_msg(struct sctp_association *asoc,
-				struct sctp_datamsg *msg)
+				struct sctp_datamsg *msg, gfp_t gfp)
 {
 	struct sctp_chunk *chunk;
 	int error = 0;
 
 	list_for_each_entry(chunk, &msg->chunks, frag_list) {
-		error = sctp_outq_tail(&asoc->outqueue, chunk);
+		error = sctp_outq_tail(&asoc->outqueue, chunk, gfp);
 		if (error)
 			break;
 	}
@@ -1249,7 +1249,7 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 		case SCTP_CMD_NEW_ASOC:
 			/* Register a new association.  */
 			if (local_cork) {
-				sctp_outq_uncork(&asoc->outqueue);
+				sctp_outq_uncork(&asoc->outqueue, gfp);
 				local_cork = 0;
 			}
 
@@ -1269,7 +1269,7 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 
 		case SCTP_CMD_DELETE_TCB:
 			if (local_cork) {
-				sctp_outq_uncork(&asoc->outqueue);
+				sctp_outq_uncork(&asoc->outqueue, gfp);
 				local_cork = 0;
 			}
 			/* Delete the current association.  */
@@ -1423,13 +1423,14 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 				local_cork = 1;
 			}
 			/* Send a chunk to our peer.  */
-			error = sctp_outq_tail(&asoc->outqueue, cmd->obj.chunk);
+			error = sctp_outq_tail(&asoc->outqueue, cmd->obj.chunk,
+					       gfp);
 			break;
 
 		case SCTP_CMD_SEND_PKT:
 			/* Send a full packet to our peer.  */
 			packet = cmd->obj.packet;
-			sctp_packet_transmit(packet);
+			sctp_packet_transmit(packet, gfp);
 			sctp_ootb_pkt_free(packet);
 			break;
 
@@ -1639,7 +1640,7 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 			 */
 			chunk->pdiscard = 1;
 			if (asoc) {
-				sctp_outq_uncork(&asoc->outqueue);
+				sctp_outq_uncork(&asoc->outqueue, gfp);
 				local_cork = 0;
 			}
 			break;
@@ -1677,7 +1678,7 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 		case SCTP_CMD_FORCE_PRIM_RETRAN:
 			t = asoc->peer.retran_path;
 			asoc->peer.retran_path = asoc->peer.primary_path;
-			error = sctp_outq_uncork(&asoc->outqueue);
+			error = sctp_outq_uncork(&asoc->outqueue, gfp);
 			local_cork = 0;
 			asoc->peer.retran_path = t;
 			break;
@@ -1704,7 +1705,7 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 				sctp_outq_cork(&asoc->outqueue);
 				local_cork = 1;
 			}
-			error = sctp_cmd_send_msg(asoc, cmd->obj.msg);
+			error = sctp_cmd_send_msg(asoc, cmd->obj.msg, gfp);
 			break;
 		case SCTP_CMD_SEND_NEXT_ASCONF:
 			sctp_cmd_send_asconf(asoc);
@@ -1734,9 +1735,9 @@ out:
 	 */
 	if (asoc && SCTP_EVENT_T_CHUNK == event_type && chunk) {
 		if (chunk->end_of_packet || chunk->singleton)
-			error = sctp_outq_uncork(&asoc->outqueue);
+			error = sctp_outq_uncork(&asoc->outqueue, gfp);
 	} else if (local_cork)
-		error = sctp_outq_uncork(&asoc->outqueue);
+		error = sctp_outq_uncork(&asoc->outqueue, gfp);
 	return error;
 nomem:
 	error = -ENOMEM;