[PATCH] cciss: direct lookup for command completions

This patch changes the way we complete commands.  In the old method when we
got a completion we searched our command list from the top until we find it.

This method uses a tag associated with each command (not SCSI command tagging)
to index us directly to the completed command.  This helps performance.

Signed-off-by: Don Brace <dab@hp.com>
Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 73 insertions, 7 deletions

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 3c6a6a21d540..a12b95eef18e 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -174,6 +174,8 @@ static int sendcmd_withirq(__u8	cmd, int ctlr, void *buff, size_t size,
         unsigned int use_unit_num, unsigned int log_unit, __u8  page_code,
         int cmd_type);
 
+static void fail_all_cmds(unsigned long ctlr);
+
 #ifdef CONFIG_PROC_FS
 static int cciss_proc_get_info(char *buffer, char **start, off_t offset, 
                 int length, int *eof, void *data);
@@ -387,6 +389,8 @@ static CommandList_struct * cmd_alloc(ctlr_info_t *h, int get_from_pool)
                         return NULL;
                 memset(c, 0, sizeof(CommandList_struct));
 
+                c->cmdindex = -1;
+
                 c->err_info = (ErrorInfo_struct *)pci_alloc_consistent(
                                         h->pdev, sizeof(ErrorInfo_struct), 
                                         &err_dma_handle);
@@ -417,6 +421,8 @@ static CommandList_struct * cmd_alloc(ctlr_info_t *h, int get_from_pool)
                 err_dma_handle = h->errinfo_pool_dhandle 
                                         + i*sizeof(ErrorInfo_struct);
                 h->nr_allocs++;
+
+                c->cmdindex = i;
         }
 
         c->busaddr = (__u32) cmd_dma_handle;
@@ -2257,7 +2263,11 @@ queue:
         /* fill in the request */ 
         drv = creq->rq_disk->private_data;
         c->Header.ReplyQueue = 0;  // unused in simple mode
-        c->Header.Tag.lower = c->busaddr;  // use the physical address the cmd block for tag
+        /* got command from pool, so use the command block index instead */
+        /* for direct lookups. */
+        /* The first 2 bits are reserved for controller error reporting. */
+        c->Header.Tag.lower = (c->cmdindex << 3);
+        c->Header.Tag.lower |= 0x04; /* flag for direct lookup. */
         c->Header.LUN.LogDev.VolId= drv->LunID;
         c->Header.LUN.LogDev.Mode = 1;
         c->Request.CDBLen = 10; // 12 byte commands not in FW yet;
@@ -2332,7 +2342,7 @@ static irqreturn_t do_cciss_intr(int irq, void *dev_id, struct pt_regs *regs)
         ctlr_info_t *h = dev_id;
         CommandList_struct *c;
         unsigned long flags;
-        __u32 a, a1;
+        __u32 a, a1, a2;
         int j;
         int start_queue = h->next_to_run;
 
@@ -2350,10 +2360,21 @@ static irqreturn_t do_cciss_intr(int irq, void *dev_id, struct pt_regs *regs)
                 while((a = h->access.command_completed(h)) != FIFO_EMPTY) 
                 {
                         a1 = a;
+                        if ((a & 0x04)) {
+                                a2 = (a >> 3);
+                                if (a2 >= NR_CMDS) {
+                                        printk(KERN_WARNING "cciss: controller cciss%d failed, stopping.\n", h->ctlr);
+                                        fail_all_cmds(h->ctlr);
+                                        return IRQ_HANDLED;
+                                }
+
+                                c = h->cmd_pool + a2;
+                                a = c->busaddr;
+
+                        } else {
                         a &= ~3;
-                        if ((c = h->cmpQ) == NULL)
-                        {  
-                                printk(KERN_WARNING "cciss: Completion of %08lx ignored\n", (unsigned long)a1);
+                                if ((c = h->cmpQ) == NULL) {
+                                        printk(KERN_WARNING "cciss: Completion of %08x ignored\n", a1);
                                 continue;       
                         } 
                         while(c->busaddr != a) {
@@ -2361,6 +2382,7 @@ static irqreturn_t do_cciss_intr(int irq, void *dev_id, struct pt_regs *regs)
                                 if (c == h->cmpQ) 
                                         break;
                         }
+                        }
                         /*
                          * If we've found the command, take it off the
                          * completion Q and free it
@@ -3124,5 +3146,43 @@ static void __exit cciss_cleanup(void)
         remove_proc_entry("cciss", proc_root_driver);
 }
 
+static void fail_all_cmds(unsigned long ctlr)
+{
+        /* If we get here, the board is apparently dead. */
+        ctlr_info_t *h = hba[ctlr];
+        CommandList_struct *c;
+        unsigned long flags;
+
+        printk(KERN_WARNING "cciss%d: controller not responding.\n", h->ctlr);
+        h->alive = 0;   /* the controller apparently died... */
+
+        spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
+
+        pci_disable_device(h->pdev); /* Make sure it is really dead. */
+
+        /* move everything off the request queue onto the completed queue */
+        while( (c = h->reqQ) != NULL ) {
+                removeQ(&(h->reqQ), c);
+                h->Qdepth--;
+                addQ (&(h->cmpQ), c);
+        }
+
+        /* Now, fail everything on the completed queue with a HW error */
+        while( (c = h->cmpQ) != NULL ) {
+                removeQ(&h->cmpQ, c);
+                c->err_info->CommandStatus = CMD_HARDWARE_ERR;
+                if (c->cmd_type == CMD_RWREQ) {
+                        complete_command(h, c, 0);
+                } else if (c->cmd_type == CMD_IOCTL_PEND)
+                        complete(c->waiting);
+#ifdef CONFIG_CISS_SCSI_TAPE
+                        else if (c->cmd_type == CMD_SCSI)
+                                complete_scsi_command(c, 0, 0);
+#endif
+        }
+        spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
+        return;
+}
+
 module_init(cciss_init);
 module_exit(cciss_cleanup);
diff --git a/drivers/block/cciss.h b/drivers/block/cciss.h
index dec27a961120..ef277baee9fd 100644
--- a/drivers/block/cciss.h
+++ b/drivers/block/cciss.h
@@ -101,6 +101,7 @@ struct ctlr_info
 #ifdef CONFIG_CISS_SCSI_TAPE
         void *scsi_ctlr; /* ptr to structure containing scsi related stuff */
 #endif
+        unsigned char alive;
 };
 
 /*  Defining the diffent access_menthods */
diff --git a/drivers/block/cciss_cmd.h b/drivers/block/cciss_cmd.h
index a88a88817623..53fea549ba8b 100644
--- a/drivers/block/cciss_cmd.h
+++ b/drivers/block/cciss_cmd.h
@@ -226,6 +226,10 @@ typedef struct _ErrorInfo_struct {
 #define CMD_MSG_DONE    0x04
 #define CMD_MSG_TIMEOUT 0x05
 
+/* This structure needs to be divisible by 8 for new
+ * indexing method.
+ */
+#define PADSIZE (sizeof(long) - 4)
 typedef struct _CommandList_struct {
   CommandListHeader_struct Header;
   RequestBlock_struct      Request;
@@ -236,14 +240,14 @@ typedef struct _CommandList_struct {
   ErrorInfo_struct *       err_info; /* pointer to the allocated mem */ 
   int                      ctlr;
   int                      cmd_type; 
+  long                     cmdindex;
   struct _CommandList_struct *prev;
   struct _CommandList_struct *next;
   struct request *         rq;
   struct completion *waiting;
   int    retry_count;
-#ifdef CONFIG_CISS_SCSI_TAPE
   void * scsi_cmd;
-#endif
+  char   pad[PADSIZE];
 } CommandList_struct;
 
 //Configuration Table Structure
diff --git a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
index f16e3caed58a..df4afacc75d7 100644
--- a/drivers/block/cciss_scsi.c
+++ b/drivers/block/cciss_scsi.c
@@ -93,6 +93,7 @@ struct cciss_scsi_cmd_stack_elem_t {
         CommandList_struct cmd;
         ErrorInfo_struct Err;
         __u32 busaddr;
+        __u32 pad;
 };
 
 #pragma pack()