@@ -203,8 +203,8 @@ 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;
@@ -213,8 +213,9 @@ typedef struct {
*/
static inline int sctp_init_cmd_seq(sctp_cmd_seq_t *seq)
{
- seq->next_free_slot = 0;
- seq->next_cmd = 0;
+ /* 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. */
}
@@ -227,10 +228,13 @@ static inline int sctp_init_cmd_seq(sctp_cmd_seq_t *seq)
static inline 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);
+ sctp_cmd_t *cmd = seq->last_used_slot - 1;
- seq->cmds[seq->next_free_slot].verb = verb;
- seq->cmds[seq->next_free_slot++].obj = obj;
+ 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.
@@ -238,12 +242,10 @@ static inline void sctp_add_cmd_sf(sctp_cmd_seq_t *seq, sctp_verb_t verb,
*/
static inline 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++];
+ if (seq->next_cmd <= seq->last_used_slot)
+ return NULL;
- return retval;
+ return --seq->next_cmd;
}
#endif /* __net_sctp_command_h__ */
Using pointers into sctp_cmd_seq_t.cmds[] lets the compiler generate much better code. Use the last entry first to optimise the overflow check. Signed-off-by: David Laight <david.laight@aculab.com> --- Changes for v2: - Delete the initialisers of next_free_slot and next_cmd that v2 of patch 2/3 adds. include/net/sctp/command.h | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-)