Merge branch 'sctp_command_queue'

David Laight says:

====================
net: sctp: Optimisations to sctp command queue code

These 3 patches optimise the code that processes sctp's command queue.
(A list of 'tasks' to be performed after the rest of the chunk processing.)

1) Inline all the functions from command.c
2) Remove the memset() calls used to zero a word-sized union.
3) Use pointers instead of array indexes.

The combined changes reduce the code size (amd64) by a few kb.

I'm not 100% convinced that the zeroing done in patch 2 is needed at all.
On BE systems it is likely to generate more code than on LE ones.
In fact it might be best to change the union to only contain 'long' sized
items.

Changes for v2:
	- Add some missing initialisers in patch 2/3 and delete them in 3/3.
	- Modify the commit message for 2/3 to point out that the union
	  shouldn't need to be zeroed, but the patches aren't intended to
	  change the behaviour even if the code is buggy.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/command.h

@@ -118,6 +118,7 @@ typedef enum {
 #define SCTP_MAX_NUM_COMMANDS 14
 
 typedef union {
+	void *zero_all;	/* Set to NULL to clear the entire union */
 	__s32 i32;
 	__u32 u32;
 	__be32 be32;
@@ -154,7 +155,7 @@ typedef union {
 static inline sctp_arg_t	\
 SCTP_## name (type arg)		\
 { sctp_arg_t retval;\
-  memset(&retval, 0, sizeof(sctp_arg_t));\
+  retval.zero_all = NULL;\
   retval.elt = arg;\
   return retval;\
 }
@@ -191,7 +192,7 @@ static inline sctp_arg_t SCTP_NOFORCE(void)
 static inline sctp_arg_t SCTP_NULL(void)
 {
 	sctp_arg_t retval;
-	memset(&retval, 0, sizeof(sctp_arg_t));
+	retval.zero_all = NULL;
 	return retval;
 }
 
@@ -202,27 +203,49 @@ typedef struct {
 
 typedef struct {
 	sctp_cmd_t cmds[SCTP_MAX_NUM_COMMANDS];
-	__u8 next_free_slot;
-	__u8 next_cmd;
+	sctp_cmd_t *last_used_slot;
+	sctp_cmd_t *next_cmd;
 } sctp_cmd_seq_t;
 
 
 /* Initialize a block of memory as a command sequence.
  * Return 0 if the initialization fails.
  */
-int sctp_init_cmd_seq(sctp_cmd_seq_t *seq);
+static inline int sctp_init_cmd_seq(sctp_cmd_seq_t *seq)
+{
+	/* cmds[] is filled backwards to simplify the overflow BUG() check */
+	seq->last_used_slot = seq->cmds + SCTP_MAX_NUM_COMMANDS;
+	seq->next_cmd = seq->last_used_slot;
+	return 1;		/* We always succeed.  */
+}
+
 
 /* Add a command to an sctp_cmd_seq_t.
  *
  * Use the SCTP_* constructors defined by SCTP_ARG_CONSTRUCTOR() above
  * to wrap data which goes in the obj argument.
  */
-void sctp_add_cmd_sf(sctp_cmd_seq_t *seq, sctp_verb_t verb, sctp_arg_t obj);
+static inline void sctp_add_cmd_sf(sctp_cmd_seq_t *seq, sctp_verb_t verb,
+				   sctp_arg_t obj)
+{
+	sctp_cmd_t *cmd = seq->last_used_slot - 1;
+
+	BUG_ON(cmd < seq->cmds);
+
+	cmd->verb = verb;
+	cmd->obj = obj;
+	seq->last_used_slot = cmd;
+}
 
 /* Return the next command structure in an sctp_cmd_seq.
  * Return NULL at the end of the sequence.
  */
-sctp_cmd_t *sctp_next_cmd(sctp_cmd_seq_t *seq);
+static inline sctp_cmd_t *sctp_next_cmd(sctp_cmd_seq_t *seq)
+{
+	if (seq->next_cmd <= seq->last_used_slot)
+		return NULL;
 
-#endif /* __net_sctp_command_h__ */
+	return --seq->next_cmd;
+}
 
+#endif /* __net_sctp_command_h__ */

net/sctp/Makefile

@@ -8,7 +8,7 @@ obj-$(CONFIG_NET_SCTPPROBE) += sctp_probe.o
 sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  protocol.o endpointola.o associola.o \
 	  transport.o chunk.o sm_make_chunk.o ulpevent.o \
-	  inqueue.o outqueue.o ulpqueue.o command.o \
+	  inqueue.o outqueue.o ulpqueue.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
 	  output.o input.o debug.o ssnmap.o auth.o
 

net/sctp/command.c

-/* SCTP kernel implementation Copyright (C) 1999-2001
- * Cisco, Motorola, and IBM
- * Copyright 2001 La Monte H.P. Yarroll
- *
- * This file is part of the SCTP kernel implementation
- *
- * These functions manipulate sctp command sequences.
- *
- * This SCTP implementation is free software;
- * you can redistribute it and/or modify it under the terms of
- * the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * This SCTP implementation is distributed in the hope that it
- * will be useful, but WITHOUT ANY WARRANTY; without even the implied
- *                 ************************
- * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- * See the GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with GNU CC; see the file COPYING.  If not, see
- * <http://www.gnu.org/licenses/>.
- *
- * Please send any bug reports or fixes you make to the
- * email address(es):
- *    lksctp developers <linux-sctp@vger.kernel.org>
- *
- * Written or modified by:
- *    La Monte H.P. Yarroll <piggy@acm.org>
- *    Karl Knutson <karl@athena.chicago.il.us>
- */
-
-#include <linux/types.h>
-#include <net/sctp/sctp.h>
-#include <net/sctp/sm.h>
-
-/* Initialize a block of memory as a command sequence. */
-int sctp_init_cmd_seq(sctp_cmd_seq_t *seq)
-{
-	memset(seq, 0, sizeof(sctp_cmd_seq_t));
-	return 1;		/* We always succeed.  */
-}
-
-/* Add a command to a sctp_cmd_seq_t.
- * Return 0 if the command sequence is full.
- */
-void sctp_add_cmd_sf(sctp_cmd_seq_t *seq, sctp_verb_t verb, sctp_arg_t obj)
-{
-	BUG_ON(seq->next_free_slot >= SCTP_MAX_NUM_COMMANDS);
-
-	seq->cmds[seq->next_free_slot].verb = verb;
-	seq->cmds[seq->next_free_slot++].obj = obj;
-}
-
-/* Return the next command structure in a sctp_cmd_seq.
- * Returns NULL at the end of the sequence.
- */
-sctp_cmd_t *sctp_next_cmd(sctp_cmd_seq_t *seq)
-{
-	sctp_cmd_t *retval = NULL;
-
-	if (seq->next_cmd < seq->next_free_slot)
-		retval = &seq->cmds[seq->next_cmd++];
-
-	return retval;
-}
-