[PATCH] net: sctp: Don't use 64 kilobyte lookup table for four elements

From: Denys Vlasenko
Date: Sat Sep 26 2015 - 14:53:30 EST


Seemingly innocuous sctp_trans_state_to_prio_map[] array
is way bigger than it looks, since
"[SCTP_UNKNOWN] = 2" expands into "[0xffff] = 2" !

This patch replaces it with switch() statement.

Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
CC: Vlad Yasevich <vyasevich@xxxxxxxxx>
CC: Neil Horman <nhorman@xxxxxxxxxxxxx>
CC: linux-sctp@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
---
net/sctp/associola.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 197c3f5..dae51ac 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1208,20 +1208,22 @@ void sctp_assoc_update(struct sctp_association *asoc,
* within this document.
*
* Our basic strategy is to round-robin transports in priorities
- * according to sctp_state_prio_map[] e.g., if no such
+ * according to sctp_trans_score() e.g., if no such
* transport with state SCTP_ACTIVE exists, round-robin through
* SCTP_UNKNOWN, etc. You get the picture.
*/
-static const u8 sctp_trans_state_to_prio_map[] = {
- [SCTP_ACTIVE] = 3, /* best case */
- [SCTP_UNKNOWN] = 2,
- [SCTP_PF] = 1,
- [SCTP_INACTIVE] = 0, /* worst case */
-};
-
static u8 sctp_trans_score(const struct sctp_transport *trans)
{
- return sctp_trans_state_to_prio_map[trans->state];
+ switch (trans->state) {
+ case SCTP_ACTIVE:
+ return 3; /* best case */
+ case SCTP_UNKNOWN:
+ return 2;
+ case SCTP_PF:
+ return 1;
+ default: /* case SCTP_INACTIVE */
+ return 0; /* worst case */
+ }
}

static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
--
1.8.1.4

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