cmd_alloc54-3.patch [3/3]

this patch implements the new command allocation scheme for SCSI
Core, using the slab cache and a free_list for each host for a
backup store of one command (or many).

 o The three (3) subversion means that it has been updated to use
   ISA DMA and PCI DMA memory for scsi command allocation,
   i.e. there's two scsi command caches now.

 o The interface is, of course, unchanged; and this is the whole
   point of making this allocation scheme -- i.e. the allocator
   is abstracted.

drivers/scsi/aic7xxx/aic79xx_osm.c

@@ -971,7 +971,7 @@ ahd_linux_queue(Scsi_Cmnd * cmd, void (*scsi_done) (Scsi_Cmnd *))
 	struct	 ahd_linux_device *dev;
 	u_long	 flags;
 
-	ahd = *(struct ahd_softc **)cmd->host->hostdata;
+	ahd = *(struct ahd_softc **)cmd->device->host->hostdata;
 
 	/*
 	 * Save the callback on completion function.
@@ -995,8 +995,8 @@ ahd_linux_queue(Scsi_Cmnd * cmd, void (*scsi_done) (Scsi_Cmnd *))
 		ahd_midlayer_entrypoint_unlock(ahd, &flags);
 		return (0);
 	}
-	dev = ahd_linux_get_device(ahd, cmd->channel, cmd->target,
-				   cmd->lun, /*alloc*/TRUE);
+	dev = ahd_linux_get_device(ahd, cmd->device->channel, cmd->device->id,
+				   cmd->device->lun, /*alloc*/TRUE);
 	if (dev == NULL) {
 		ahd_midlayer_entrypoint_unlock(ahd, &flags);
 		printf("aic79xx_linux_queue: Unable to allocate device!\n");
@@ -1217,7 +1217,7 @@ ahd_linux_abort(Scsi_Cmnd *cmd)
 	int    found;
 #endif
 
-	ahd = *(struct ahd_softc **)cmd->host->hostdata;
+	ahd = *(struct ahd_softc **)cmd->device->host->hostdata;
 #if NOTYET
 	int error;
 
@@ -1251,7 +1251,7 @@ ahd_linux_dev_reset(Scsi_Cmnd *cmd)
 	int    found;
 #endif
 
-	ahd = *(struct ahd_softc **)cmd->host->hostdata;
+	ahd = *(struct ahd_softc **)cmd->device->host->hostdata;
 #ifdef AHD_DEBUG
 	if ((ahd_debug & AHD_SHOW_RECOVERY) != 0)
 		printf("%s: Dev reset called for cmd %p\n",
@@ -1283,14 +1283,14 @@ ahd_linux_bus_reset(Scsi_Cmnd *cmd)
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
 	spin_unlock_irq(&io_request_lock);
 #endif
-	ahd = *(struct ahd_softc **)cmd->host->hostdata;
+	ahd = *(struct ahd_softc **)cmd->device->host->hostdata;
 #ifdef AHD_DEBUG
 	if ((ahd_debug & AHD_SHOW_RECOVERY) != 0)
 		printf("%s: Bus reset called for cmd %p\n",
 		       ahd_name(ahd), cmd);
 #endif
 	ahd_midlayer_entrypoint_lock(ahd, &s);
-	found = ahd_reset_channel(ahd, cmd->channel + 'A',
+	found = ahd_reset_channel(ahd, cmd->device->channel + 'A',
 				  /*initiate reset*/TRUE);
 	acmd = TAILQ_FIRST(&ahd->platform_data->completeq);
 	TAILQ_INIT(&ahd->platform_data->completeq);
@@ -1415,7 +1415,7 @@ static int ahd_linux_halt(struct notifier_block *nb, u_long event, void *buf)
 
 /******************************** Macros **************************************/
 #define BUILD_SCSIID(ahd, cmd)						\
-	((((cmd)->target << TID_SHIFT) & TID) | (ahd)->our_id)
+	((((cmd)->device->id << TID_SHIFT) & TID) | (ahd)->our_id)
 
 /******************************** Bus DMA *************************************/
 int
@@ -3668,7 +3668,7 @@ ahd_linux_dv_timeout(struct scsi_cmnd *cmd)
 	struct	scb *scb;
 	u_long	flags;
 
-	ahd = *((struct ahd_softc **)cmd->host->hostdata);
+	ahd = *((struct ahd_softc **)cmd->device->host->hostdata);
 	ahd_lock(ahd, &flags);
 
 #ifdef AHD_DEBUG
@@ -3696,7 +3696,7 @@ ahd_linux_dv_timeout(struct scsi_cmnd *cmd)
 		ahd_set_transaction_status(scb, CAM_AUTOSENSE_FAIL);
 	else
 		ahd_set_transaction_status(scb, CAM_CMD_TIMEOUT);
-	ahd_reset_channel(ahd, cmd->channel + 'A', /*initiate*/TRUE);
+	ahd_reset_channel(ahd, cmd->device->channel + 'A', /*initiate*/TRUE);
 
 	/*
 	 * Add a minimal bus settle delay for devices that are slow to
@@ -3746,7 +3746,7 @@ ahd_linux_dv_complete(struct scsi_cmnd *cmd)
 {
 	struct ahd_softc *ahd;
 
-	ahd = *((struct ahd_softc **)cmd->host->hostdata);
+	ahd = *((struct ahd_softc **)cmd->device->host->hostdata);
 
 	/* Delete the DV timer before it goes off! */
 	scsi_delete_timer(cmd);
@@ -3754,7 +3754,8 @@ ahd_linux_dv_complete(struct scsi_cmnd *cmd)
 #ifdef AHD_DEBUG
 	if (ahd_debug & AHD_SHOW_DV)
 		printf("%s:%c:%d: Command completed, status= 0x%x\n",
-		       ahd_name(ahd), cmd->channel, cmd->target, cmd->result);
+		       ahd_name(ahd), cmd->device->channel,
+		       cmd->device->id, cmd->result);
 #endif
 
 	/* Wake up the state machine */
@@ -3948,12 +3949,13 @@ ahd_linux_run_device_queue(struct ahd_softc *ahd, struct ahd_linux_device *dev)
 		 * Get an scb to use.
 		 */
 		tinfo = ahd_fetch_transinfo(ahd, 'A', ahd->our_id,
-					    cmd->target, &tstate);
+					    cmd->device->id, &tstate);
 		if ((dev->flags & (AHD_DEV_Q_TAGGED|AHD_DEV_Q_BASIC)) == 0
 		 || (tinfo->curr.ppr_options & MSG_EXT_PPR_IU_REQ) != 0) {
 			col_idx = AHD_NEVER_COL_IDX;
 		} else {
-			col_idx = AHD_BUILD_COL_IDX(cmd->target, cmd->lun);
+			col_idx = AHD_BUILD_COL_IDX(cmd->device->id,
+						    cmd->device->lun);
 		}
 		if ((scb = ahd_get_scb(ahd, col_idx)) == NULL) {
 			TAILQ_INSERT_TAIL(&ahd->platform_data->device_runq,
@@ -3973,7 +3975,7 @@ ahd_linux_run_device_queue(struct ahd_softc *ahd, struct ahd_linux_device *dev)
 		 */
 		hscb->control = 0;
 		hscb->scsiid = BUILD_SCSIID(ahd, cmd);
-		hscb->lun = cmd->lun;
+		hscb->lun = cmd->device->lun;
 		mask = SCB_GET_TARGET_MASK(ahd, scb);
 
 		if ((ahd->user_discenable & mask) != 0)
@@ -4641,8 +4643,9 @@ ahd_linux_queue_cmd_complete(struct ahd_softc *ahd, Scsi_Cmnd *cmd)
 			struct ahd_devinfo devinfo;
 			uint32_t action;
 
-			dev = ahd_linux_get_device(ahd, cmd->channel,
-						   cmd->target, cmd->lun,
+			dev = ahd_linux_get_device(ahd, cmd->device->channel,
+						   cmd->device->id,
+						   cmd->device->lun,
 						   /*alloc*/FALSE);
 
 			if (dev == NULL)

drivers/scsi/cpqfcTSinit.c

@@ -1603,8 +1603,7 @@ return -ENOTSUPP;
 
   scsi_cdb[0] = RELEASE;
 
-  // allocate with wait = true, interruptible = false 
-  SCpnt = scsi_allocate_device(ScsiDev, 1);
+  SCpnt = scsi_getset_command(ScsiDev, GFP_KERNEL);
   {
     CPQFC_DECLARE_COMPLETION(wait);
     
@@ -1653,7 +1652,7 @@ return -ENOTSUPP;
   result = SCpnt->result;
 
   SDpnt = SCpnt->device;
-  scsi_release_command(SCpnt);
+  scsi_put_command(SCpnt);
   SCpnt = NULL;
 
   // if (!SDpnt->was_reset && SDpnt->scsi_request_fn)

drivers/scsi/gdth.c

@@ -4599,7 +4599,7 @@ static void gdth_flush(int hanum)
 
 #if LINUX_VERSION_CODE >= 0x020322
     sdev = scsi_get_host_dev(gdth_ctr_tab[hanum]);
-    scp  = scsi_allocate_device(sdev, 1);
+    scp  = scsi_getset_command(sdev, GFP_KERNEL);
     scp->cmd_len = 12;
     scp->use_sg = 0;
 #else
@@ -4627,7 +4627,7 @@ static void gdth_flush(int hanum)
         }
     }
 #if LINUX_VERSION_CODE >= 0x020322
-    scsi_release_command(scp);
+    scsi_put_command(scp);
     scsi_free_host_dev(sdev);
 #endif
 }
@@ -4673,7 +4673,7 @@ void gdth_halt(void)
         memset(cmnd, 0xff, MAX_COMMAND_SIZE);
 #if LINUX_VERSION_CODE >= 0x020322
         sdev = scsi_get_host_dev(gdth_ctr_tab[hanum]);
-        scp  = scsi_allocate_device(sdev, 1);
+        scp  = scsi_getset_command(sdev, GFP_KERNEL);
         scp->cmd_len = 12;
         scp->use_sg = 0;
 #else
@@ -4690,7 +4690,7 @@ void gdth_halt(void)
         TRACE2(("gdth_halt(): reset controller %d\n", hanum));
 #if LINUX_VERSION_CODE >= 0x020322
         gdth_do_cmd(scp, &gdtcmd, cmnd, 10);
-        scsi_release_command(scp);
+        scsi_put_command(scp);
         scsi_free_host_dev(sdev);
 #else
         gdth_do_cmd(&scp, &gdtcmd, cmnd, 10);

drivers/scsi/gdth_proc.c

@@ -48,7 +48,7 @@ static int gdth_set_info(char *buffer,int length,int vh,int hanum,int busnum)
 
 #if LINUX_VERSION_CODE >= 0x020322
     sdev = scsi_get_host_dev(gdth_ctr_vtab[vh]);
-    scp  = scsi_allocate_device(sdev, 1);
+    scp  = scsi_getset_command(sdev, GFP_KERNEL);
     if (!scp)
         return -ENOMEM;
     scp->cmd_len = 12;
@@ -81,7 +81,7 @@ static int gdth_set_info(char *buffer,int length,int vh,int hanum,int busnum)
         ret_val = -EINVAL;
     }
 #if LINUX_VERSION_CODE >= 0x020322
-    scsi_release_command(scp);
+    scsi_put_command(scp);
     scsi_free_host_dev(sdev);
 #endif
     return ret_val;
@@ -712,7 +712,7 @@ static int gdth_get_info(char *buffer,char **start,off_t offset,
 
 #if LINUX_VERSION_CODE >= 0x020322
     sdev = scsi_get_host_dev(gdth_ctr_vtab[vh]);
-    scp  = scsi_allocate_device(sdev, 1);
+    scp  = scsi_getset_command(sdev, GFP_KERNEL);
     if (!scp)
         return -ENOMEM;
     scp->cmd_len = 12;
@@ -1234,7 +1234,7 @@ static int gdth_get_info(char *buffer,char **start,off_t offset,
 
 stop_output:
 #if LINUX_VERSION_CODE >= 0x020322
-    scsi_release_command(scp);
+    scsi_put_command(scp);
     scsi_free_host_dev(sdev);
 #endif
     *start = buffer +(offset-begin);

drivers/scsi/hosts.c

@@ -347,6 +347,13 @@ void scsi_unregister(struct Scsi_Host *shost)
 	/* Cleanup proc */
 	scsi_proc_host_rm(shost);
 
+	while (!list_empty(&shost->free_list)) {
+		struct scsi_cmnd *cmd;
+		cmd = list_entry(shost->free_list.next,struct scsi_cmnd,list);
+		list_del_init(&cmd->list);
+		kmem_cache_free(scsi_core->scsi_cmd_cache, cmd);
+	}
+
 	kfree(shost);
 }
 
@@ -367,6 +374,7 @@ extern int blk_nohighio;
 struct Scsi_Host * scsi_register(Scsi_Host_Template *shost_tp, int xtr_bytes)
 {
 	struct Scsi_Host *shost, *shost_scr;
+	struct scsi_cmnd *cmd = NULL;
 	int gfp_mask;
 	DECLARE_MUTEX_LOCKED(sem);
 
@@ -456,6 +464,16 @@ struct Scsi_Host * scsi_register(Scsi_Host_Template *shost_tp, int xtr_bytes)
 found:
 	spin_unlock(&scsi_host_list_lock);
 
+	spin_lock_init(&shost->free_list_lock);
+	INIT_LIST_HEAD(&shost->free_list);
+
+	/* Get one backup command for this host. */
+	cmd = scsi_get_command(shost, GFP_KERNEL);
+	if (cmd)
+		list_add(&cmd->list, &shost->free_list);		
+	else
+		printk(KERN_NOTICE "The system is running low in memory.\n");
+
 	scsi_proc_host_add(shost);
 
 	shost->eh_notify = &sem;

drivers/scsi/hosts.h

@@ -375,6 +375,9 @@ struct Scsi_Host
     struct list_head      sh_list;
     struct list_head	  my_devices;
 
+    spinlock_t            free_list_lock;
+    struct list_head      free_list;   /* backup store of cmd structs */
+
     spinlock_t		  default_lock;
     spinlock_t		  *host_lock;
 

drivers/scsi/scsi.c

@@ -265,7 +265,7 @@ void scsi_release_request(Scsi_Request * req)
 {
 	if( req->sr_command != NULL )
 	{
-		scsi_release_command(req->sr_command);
+		scsi_put_command(req->sr_command);
 		req->sr_command = NULL;
 	}
 
@@ -768,7 +768,7 @@ void scsi_wait_req (Scsi_Request * SRpnt, const void *cmnd ,
 	SRpnt->sr_request->waiting = NULL;
 	if( SRpnt->sr_command != NULL )
 	{
-		scsi_release_command(SRpnt->sr_command);
+		scsi_put_command(SRpnt->sr_command);
 		SRpnt->sr_command = NULL;
 	}
 
@@ -834,7 +834,7 @@ void scsi_do_req(Scsi_Request * SRpnt, const void *cmnd,
 	 */
 	if( SRpnt->sr_command != NULL )
 	{
-		scsi_release_command(SRpnt->sr_command);
+		scsi_put_command(SRpnt->sr_command);
 		SRpnt->sr_command = NULL;
 	}
 
@@ -1506,6 +1506,12 @@ void scsi_adjust_queue_depth(Scsi_Device *SDpnt, int tagged, int tags)
 			SDpnt->new_queue_depth = tags;
 			break;
 	}
+	/* TODO FIXME This is a hack and MUST go eventually.
+	   This fixes a problem in scsi_scan.c::scsi_alloc_sdev()
+	   else we cannot ever have ANY SCSI devices.
+	*/
+	SDpnt->current_queue_depth = 1;
+
 	spin_unlock_irqrestore(&device_request_lock, flags);
 }
 
@@ -2017,6 +2023,14 @@ static int __init init_scsi(void)
 {
 	printk(KERN_INFO "SCSI subsystem driver " REVISION "\n");
 
+	scsi_core = kmalloc(sizeof(*scsi_core), GFP_KERNEL);
+	if (!scsi_core)
+		goto out_no_mem;
+	memset(scsi_core, 0, sizeof(*scsi_core));
+	
+	if (scsi_create_cmdcache(scsi_core))
+		goto out_no_mem;
+
 	scsi_init_queue();
 	scsi_init_procfs();
 	devfs_mk_dir(NULL, "scsi", NULL);
@@ -2025,6 +2039,10 @@ static int __init init_scsi(void)
 	scsi_sysfs_register();
 	open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);
 	return 0;
+
+out_no_mem:
+	printk(KERN_CRIT "Couldn't load SCSI Core -- out of memory!\n");
+	return -ENOMEM;
 }
 
 static void __exit exit_scsi(void)
@@ -2034,6 +2052,12 @@ static void __exit exit_scsi(void)
 	devfs_remove("scsi");
 	scsi_exit_procfs();
 	scsi_exit_queue();
+
+	scsi_destroy_cmdcache(scsi_core);
+
+	if (scsi_core)
+		kfree(scsi_core);
+	scsi_core = NULL;
 }
 
 subsys_initcall(init_scsi);

drivers/scsi/scsi.h

@@ -734,7 +734,8 @@ struct scsi_cmnd {
 	Scsi_Request *sc_request;
 	struct scsi_cmnd *next;
 	struct scsi_cmnd *reset_chain;
-	struct list_head list_entry; /* Used to place us on the cmd lists */
+
+	struct list_head list;  /* scsi_cmnd participates in queue lists */
 
 	int eh_state;		/* Used for state tracking in error handlr */
 	int eh_eflags;		/* Used by error handlr */
@@ -994,4 +995,45 @@ extern void scsi_device_unregister(struct scsi_device *);
 extern int scsi_sysfs_register(void);
 extern void scsi_sysfs_unregister(void);
 
+/* -------------------------------------------------- */
+/* data decl: */
+
+/* All the SCSI Core specific global data, etc,
+   should go in here.
+*/
+
+struct scsi_core_data {
+	kmem_cache_t   *scsi_cmd_cache;
+	kmem_cache_t   *scsi_cmd_dma_cache;
+};
+
+extern struct scsi_core_data *scsi_core;
+
+/* -------------------------------------------------- */
+/* fn decl: */
+
+int scsi_create_cmdcache(struct scsi_core_data *scsi_core);
+int scsi_destroy_cmdcache(struct scsi_core_data *scsi_core);
+
+struct scsi_cmnd * scsi_get_command(struct Scsi_Host *host, int alloc_flags);
+void scsi_put_command(struct scsi_cmnd *cmd);
+void scsi_setup_command(struct scsi_device *dev, struct scsi_cmnd *cmd);
+
+/* -------------------------------------------------- */
+/* inline funcs: */
+
+/* scsi_getset_command: allocate, set and return a command struct,
+   when the device is known.
+*/
+static inline struct scsi_cmnd *scsi_getset_command(struct scsi_device *dev,
+						    int flags)
+{
+	struct scsi_cmnd *cmd;
+
+	if (!dev) return NULL;
+	if (!dev->host) return NULL;
+	scsi_setup_command(dev, (cmd = scsi_get_command(dev->host, flags)));
+	return cmd;
+}				
+
 #endif

drivers/scsi/scsi_error.c

@@ -1384,7 +1384,7 @@ static void scsi_eh_lock_done(struct scsi_cmnd *scmd)
 	scmd->sc_request = NULL;
 	sreq->sr_command = NULL;
 
-	scsi_release_command(scmd);
+	scsi_put_command(scmd);
 	scsi_release_request(sreq);
 }
 

drivers/scsi/scsi_lib.c

@@ -33,7 +33,9 @@ struct scsi_host_sg_pool {
 struct scsi_host_sg_pool scsi_sg_pools[SG_MEMPOOL_NR] = { 
 	SP(8), SP(16), SP(32), SP(64), SP(MAX_PHYS_SEGMENTS)
 }; 	
-#undef SP 	
+#undef SP
+
+struct scsi_core_data *scsi_core;
 
 /*
  * Function:    scsi_insert_special_cmd()
@@ -357,7 +359,7 @@ static Scsi_Cmnd *scsi_end_request(Scsi_Cmnd * SCpnt,
 	 * This will goose the queue request function at the end, so we don't
 	 * need to worry about launching another command.
 	 */
-	__scsi_release_command(SCpnt);
+	scsi_put_command(SCpnt);
 	scsi_queue_next_request(q, NULL);
 	return NULL;
 }
@@ -802,7 +804,8 @@ int scsi_prep_fn(struct request_queue *q, struct request *req)
 		SRpnt = (Scsi_Request *) req->special;
 		
 		if( SRpnt->sr_magic == SCSI_REQ_MAGIC ) {
-			SCpnt = scsi_allocate_device(SRpnt->sr_device, 0);
+			SCpnt = scsi_getset_command(SRpnt->sr_device,
+						    GFP_ATOMIC);
 			if (!SCpnt)
 				return BLKPREP_DEFER;
 			scsi_init_cmd_from_req(SCpnt, SRpnt);
@@ -815,7 +818,7 @@ int scsi_prep_fn(struct request_queue *q, struct request *req)
 		if (req->special) {
 			SCpnt = (Scsi_Cmnd *) req->special;
 		} else {
-			SCpnt = scsi_allocate_device(SDpnt, 0);
+			SCpnt = scsi_getset_command(SDpnt, GFP_ATOMIC);
 		}
 		/*
 		 * if command allocation failure, wait a bit
@@ -1179,3 +1182,143 @@ void __exit scsi_exit_queue(void)
 		kmem_cache_destroy(sgp->slab);
 	}
 }
+
+/* -------------------------------------------------- */
+
+int scsi_create_cmdcache(struct scsi_core_data *scsi_core)
+{
+	if (!scsi_core)
+		return -EFAULT;
+
+	scsi_core->scsi_cmd_cache
+		= kmem_cache_create("scsi_cmd_cache",
+				    sizeof(struct scsi_cmnd), 0,
+				    SLAB_NO_REAP|SLAB_HWCACHE_ALIGN,NULL,NULL);
+	if (!scsi_core->scsi_cmd_cache)
+		return -ENOMEM;
+
+	scsi_core->scsi_cmd_dma_cache
+		= kmem_cache_create("scsi_cmd_cache(DMA)",
+				    sizeof(struct scsi_cmnd), 0,
+				    SLAB_NO_REAP|SLAB_HWCACHE_ALIGN
+				    |SLAB_CACHE_DMA,
+				    NULL,NULL);
+	if (!scsi_core->scsi_cmd_dma_cache) {
+		scsi_destroy_cmdcache(scsi_core);
+		return -ENOMEM;
+	}
+	return 0;
+} /* end scsi_create_cmdcache() */
+
+/* -------------------------------------------------- */
+
+int scsi_destroy_cmdcache(struct scsi_core_data *scsi_core)
+{
+	if (!scsi_core)
+		return -EFAULT;
+
+	if (scsi_core->scsi_cmd_cache &&
+	    kmem_cache_destroy(scsi_core->scsi_cmd_cache)) {
+		goto bail;
+	} else {
+		scsi_core->scsi_cmd_cache = NULL;
+	}
+
+	if (scsi_core->scsi_cmd_dma_cache &&
+	    kmem_cache_destroy(scsi_core->scsi_cmd_dma_cache)) {
+		goto bail;
+	} else {
+		scsi_core->scsi_cmd_dma_cache = NULL;
+	}
+		
+	return 0;
+bail:
+	printk(KERN_CRIT "Failed to free scsi command cache"
+	       " -- memory leak\n");
+	return -EFAULT;
+} /* end scsi_destroy_cmdcache() */
+
+/* -------------------------------------------------- */
+
+struct scsi_cmnd * scsi_get_command(struct Scsi_Host *host, int alloc_flags)
+{
+	unsigned long flags;
+	struct scsi_cmnd *cmd = NULL;
+	
+	if (!host)
+		return NULL;
+
+	if (host->unchecked_isa_dma) {
+		cmd = kmem_cache_alloc(scsi_core->scsi_cmd_dma_cache,
+				       alloc_flags);
+	} else {
+		cmd = kmem_cache_alloc(scsi_core->scsi_cmd_cache, alloc_flags);
+	}
+
+	if (!cmd) {
+		spin_lock_irqsave(&host->free_list_lock, flags);
+		if (!list_empty(&host->free_list)) {
+			cmd = list_entry(host->free_list.next,
+					 struct scsi_cmnd, list);
+			list_del_init(&cmd->list);
+		}
+		spin_unlock_irqrestore(&host->free_list_lock, flags);
+	}
+
+	return cmd;
+} /* end scsi_get_command() */
+
+/* -------------------------------------------------- */
+/* scsi_put_command: free a scsi_cmnd struct.
+   Note: the command must not belong to any lists!
+*/
+void scsi_put_command(struct scsi_cmnd *cmd)
+{
+	unsigned long flags;
+	struct Scsi_Host *host;
+	
+	if (!cmd)
+		return;
+
+	if (!cmd->device || !cmd->device->host) {
+		printk(KERN_NOTICE "Trying to free a command which"
+		       " doesn't belong to scsi core?!\n");
+		 /* Memory leak, but let the system survive for now --
+		    they'll get it eventually! */
+		return;
+	}
+
+	host = cmd->device->host;
+
+	spin_lock_irqsave(&host->free_list_lock, flags);
+	if (list_empty(&host->free_list)) {
+		list_add(&cmd->list, &host->free_list);
+		cmd = NULL;
+	}
+	spin_unlock_irqrestore(&host->free_list_lock, flags);
+
+	if (cmd) {
+		if (host->unchecked_isa_dma)
+			kmem_cache_free(scsi_core->scsi_cmd_dma_cache, cmd);
+		else
+			kmem_cache_free(scsi_core->scsi_cmd_cache, cmd);
+	}
+} /* end scsi_put_command() */
+
+/* -------------------------------------------------- */
+/* scsi_setup_command: This will do post-alloc init of the command.
+   We want to do as little as possible here.
+*/
+void scsi_setup_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
+{
+	if (!cmd)
+		return;
+	memset(cmd, 0, sizeof(*cmd));
+	cmd->device = dev;
+	cmd->state = SCSI_STATE_UNUSED;
+	cmd->owner = SCSI_OWNER_NOBODY;
+	init_timer(&cmd->eh_timeout);
+	INIT_LIST_HEAD(&cmd->list);
+} /* end scsi_setup_command() */
+
+/* -------------------------------------------------- */

drivers/scsi/scsi_scan.c

@@ -471,7 +471,6 @@ static struct scsi_device *scsi_alloc_sdev(struct Scsi_Host *shost,
 
 		sdev->request_queue->queuedata = sdev;
 		scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
-		scsi_build_commandblocks(sdev);
 		if (sdev->current_queue_depth == 0) {
 			goto out_bail;
 		}
@@ -515,7 +514,6 @@ static struct scsi_device *scsi_alloc_sdev(struct Scsi_Host *shost,
 	} else if (sdev->request_queue)
 		scsi_free_queue(sdev->request_queue);
 
-	scsi_release_commandblocks(sdev);
 	kfree(sdev);
 	return NULL;
 }
@@ -535,7 +533,6 @@ static void scsi_free_sdev(struct scsi_device *sdev)
 
 	if (sdev->request_queue)
 		scsi_free_queue(sdev->request_queue);
-	scsi_release_commandblocks(sdev);
 	if (sdev->host->hostt->slave_destroy)
 		sdev->host->hostt->slave_destroy(sdev);
 	if (sdev->inquiry)

drivers/scsi/scsi_syms.c

@@ -39,7 +39,6 @@ EXPORT_SYMBOL(scsi_unregister);
 EXPORT_SYMBOL(scsicam_bios_param);
 EXPORT_SYMBOL(scsi_partsize);
 EXPORT_SYMBOL(scsi_bios_ptable);
-EXPORT_SYMBOL(scsi_allocate_device);
 EXPORT_SYMBOL(scsi_do_cmd);
 EXPORT_SYMBOL(scsi_ioctl);
 EXPORT_SYMBOL(print_command);
@@ -50,7 +49,6 @@ EXPORT_SYMBOL(print_status);
 EXPORT_SYMBOL(scsi_sense_key_string);
 EXPORT_SYMBOL(scsi_extd_sense_format);
 EXPORT_SYMBOL(kernel_scsi_ioctl);
-EXPORT_SYMBOL(scsi_release_command);
 EXPORT_SYMBOL(print_Scsi_Cmnd);
 EXPORT_SYMBOL(scsi_block_when_processing_errors);
 EXPORT_SYMBOL(scsi_ioctl_send_command);
@@ -114,3 +112,8 @@ EXPORT_SYMBOL(scsi_delete_timer);
  * sysfs support
  */
 EXPORT_SYMBOL(shost_devclass);
+
+EXPORT_SYMBOL(scsi_get_command);
+EXPORT_SYMBOL(scsi_put_command);
+EXPORT_SYMBOL(scsi_setup_command);
+