- Try pre-allocating all FIBs upfront. Previously we tried pre-allocating

128 FIBs first and allocated more later if necessary.  Remove now unused
definitions from the header file[1].
- Force sequential bus scanning.  It seems parallel scanning is in fact
slower and causes more harm than good[1].  Adjust a comment to reflect that.

PR:		kern/141269
Submitted by:	Alexander Sack (asack at niksun dot com)[1]
Reviewed by:	scottl

sys/dev/aac/aac.c

@@ -604,7 +604,7 @@ aac_alloc(struct aac_softc *sc)
 	TAILQ_INIT(&sc->aac_fibmap_tqh);
 	sc->aac_commands = malloc(sc->aac_max_fibs * sizeof(struct aac_command),
 				  M_AACBUF, M_WAITOK|M_ZERO);
-	while (sc->total_fibs < AAC_PREALLOCATE_FIBS) {
+	while (sc->total_fibs < sc->aac_max_fibs) {
 		if (aac_alloc_commands(sc) != 0)
 			break;
 	}

sys/dev/aac/aac_cam.c

@@ -260,8 +260,11 @@ aac_cam_action(struct cam_sim *sim, union ccb *ccb)
 		cpi->hba_inquiry = PI_WIDE_16;
 		cpi->target_sprt = 0;
 
-		/* Resetting via the passthrough causes problems. */
-		cpi->hba_misc = PIM_NOBUSRESET;
+		/*
+		 * Resetting via the passthrough or parallel bus scan
+		 * causes problems.
+		 */
+		cpi->hba_misc = PIM_NOBUSRESET | PIM_SEQSCAN;
 		cpi->hba_eng_cnt = 0;
 		cpi->max_target = camsc->inf->TargetsPerBus;
 		cpi->max_lun = 8;	/* Per the controller spec */

sys/dev/aac/aacvar.h

@@ -56,13 +56,6 @@
  */
 #define AAC_ADAPTER_FIBS	8
 
-/*
- * FIBs are allocated in page-size chunks and can grow up to the 512
- * limit imposed by the hardware.
- */
-#define AAC_PREALLOCATE_FIBS	128
-#define AAC_NUM_MGT_FIB		8
-
 /*
  * The controller reports status events in AIFs.  We hang on to a number of
  * these in order to pass them out to user-space management tools.