cciss: switch to using hlist for command list management

This both cleans up the code and also helps detect the spurious case
of a command attempted being removed from a queue it doesn't belong
to.

Acked-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 33 insertions, 46 deletions

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 9f7c543cc04b..4e07b5ca847c 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -215,31 +215,17 @@ static struct block_device_operations cciss_fops = {
 /*
  * Enqueuing and dequeuing functions for cmdlists.
  */
-static inline void addQ(CommandList_struct **Qptr, CommandList_struct *c)
+static inline void addQ(struct hlist_head *list, CommandList_struct *c)
 {
-        if (*Qptr == NULL) {
-                *Qptr = c;
-                c->next = c->prev = c;
-        } else {
-                c->prev = (*Qptr)->prev;
-                c->next = (*Qptr);
-                (*Qptr)->prev->next = c;
-                (*Qptr)->prev = c;
-        }
+        hlist_add_head(&c->list, list);
 }
 
-static inline CommandList_struct *removeQ(CommandList_struct **Qptr,
-                                          CommandList_struct *c)
+static inline void removeQ(CommandList_struct *c)
 {
-        if (c && c->next != c) {
-                if (*Qptr == c)
-                        *Qptr = c->next;
-                c->prev->next = c->next;
-                c->next->prev = c->prev;
-        } else {
-                *Qptr = NULL;
-        }
-        return c;
+        if (WARN_ON(hlist_unhashed(&c->list)))
+                return;
+
+        hlist_del_init(&c->list);
 }
 
 #include "cciss_scsi.c"         /* For SCSI tape support */
@@ -506,6 +492,7 @@ static CommandList_struct *cmd_alloc(ctlr_info_t *h, int get_from_pool)
                 c->cmdindex = i;
         }
 
+        INIT_HLIST_NODE(&c->list);
         c->busaddr = (__u32) cmd_dma_handle;
         temp64.val = (__u64) err_dma_handle;
         c->ErrDesc.Addr.lower = temp64.val32.lower;
@@ -2548,7 +2535,8 @@ static void start_io(ctlr_info_t *h)
 {
         CommandList_struct *c;
 
-        while ((c = h->reqQ) != NULL) {
+        while (!hlist_empty(&h->reqQ)) {
+                c = hlist_entry(h->reqQ.first, CommandList_struct, list);
                 /* can't do anything if fifo is full */
                 if ((h->access.fifo_full(h))) {
                         printk(KERN_WARNING "cciss: fifo full\n");
@@ -2556,14 +2544,14 @@ static void start_io(ctlr_info_t *h)
                 }
 
                 /* Get the first entry from the Request Q */
-                removeQ(&(h->reqQ), c);
+                removeQ(c);
                 h->Qdepth--;
 
                 /* Tell the controller execute command */
                 h->access.submit_command(h, c);
 
                 /* Put job onto the completed Q */
-                addQ(&(h->cmpQ), c);
+                addQ(&h->cmpQ, c);
         }
 }
 
@@ -2576,7 +2564,7 @@ static inline void resend_cciss_cmd(ctlr_info_t *h, CommandList_struct *c)
         memset(c->err_info, 0, sizeof(ErrorInfo_struct));
 
         /* add it to software queue and then send it to the controller */
-        addQ(&(h->reqQ), c);
+        addQ(&h->reqQ, c);
         h->Qdepth++;
         if (h->Qdepth > h->maxQsinceinit)
                 h->maxQsinceinit = h->Qdepth;
@@ -2897,7 +2885,7 @@ static void do_cciss_request(struct request_queue *q)
 
         spin_lock_irq(q->queue_lock);
 
-        addQ(&(h->reqQ), c);
+        addQ(&h->reqQ, c);
         h->Qdepth++;
         if (h->Qdepth > h->maxQsinceinit)
                 h->maxQsinceinit = h->Qdepth;
@@ -2985,16 +2973,12 @@ static irqreturn_t do_cciss_intr(int irq, void *dev_id)
                                 a = c->busaddr;
 
                         } else {
+                                struct hlist_node *tmp;
+
                                 a &= ~3;
-                                if ((c = h->cmpQ) == NULL) {
-                                        printk(KERN_WARNING
-                                               "cciss: Completion of %08x ignored\n",
-                                               a1);
-                                        continue;
-                                }
-                                while (c->busaddr != a) {
-                                        c = c->next;
-                                        if (c == h->cmpQ)
+                                c = NULL;
+                                hlist_for_each_entry(c, tmp, &h->cmpQ, list) {
+                                        if (c->busaddr == a)
                                                 break;
                                 }
                         }
@@ -3002,8 +2986,8 @@ static irqreturn_t do_cciss_intr(int irq, void *dev_id)
                          * If we've found the command, take it off the
                          * completion Q and free it
                          */
-                        if (c->busaddr == a) {
-                                removeQ(&h->cmpQ, c);
+                        if (c && c->busaddr == a) {
+                                removeQ(c);
                                 if (c->cmd_type == CMD_RWREQ) {
                                         complete_command(h, c, 0);
                                 } else if (c->cmd_type == CMD_IOCTL_PEND) {
@@ -3423,6 +3407,8 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
                 return -1;
 
         hba[i]->busy_initializing = 1;
+        INIT_HLIST_HEAD(&hba[i]->cmpQ);
+        INIT_HLIST_HEAD(&hba[i]->reqQ);
 
         if (cciss_pci_init(hba[i], pdev) != 0)
                 goto clean1;
@@ -3730,15 +3716,17 @@ static void fail_all_cmds(unsigned long ctlr)
         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);
+        while (!hlist_empty(&h->reqQ)) {
+                c = hlist_entry(h->reqQ.first, CommandList_struct, list);
+                removeQ(c);
                 h->Qdepth--;
-                addQ(&(h->cmpQ), c);
+                addQ(&h->cmpQ, c);
         }
 
         /* Now, fail everything on the completed queue with a HW error */
-        while ((c = h->cmpQ) != NULL) {
-                removeQ(&h->cmpQ, c);
+        while (!hlist_empty(&h->cmpQ)) {
+                c = hlist_entry(h->cmpQ.first, CommandList_struct, list);
+                removeQ(c);
                 c->err_info->CommandStatus = CMD_HARDWARE_ERR;
                 if (c->cmd_type == CMD_RWREQ) {
                         complete_command(h, c, 0);
diff --git a/drivers/block/cciss.h b/drivers/block/cciss.h
index 24a7efa993ab..15e2b84734e3 100644
--- a/drivers/block/cciss.h
+++ b/drivers/block/cciss.h
@@ -89,8 +89,8 @@ struct ctlr_info
         struct access_method access;
 
         /* queue and queue Info */ 
-        CommandList_struct *reqQ;
-        CommandList_struct  *cmpQ;
+        struct hlist_head reqQ;
+        struct hlist_head cmpQ;
         unsigned int Qdepth;
         unsigned int maxQsinceinit;
         unsigned int maxSG;
diff --git a/drivers/block/cciss_cmd.h b/drivers/block/cciss_cmd.h
index 43bf5593b59b..24e22dea1a99 100644
--- a/drivers/block/cciss_cmd.h
+++ b/drivers/block/cciss_cmd.h
@@ -265,8 +265,7 @@ typedef struct _CommandList_struct {
   int                      ctlr;
   int                      cmd_type; 
   long                     cmdindex;
-  struct _CommandList_struct *prev;
-  struct _CommandList_struct *next;
+  struct hlist_node list;
   struct request *         rq;
   struct completion *waiting;
   int    retry_count;