hpsa: use atomics for commands_outstanding

Use atomics for commands_outstanding instead of protecting with spin locks.

Signed-off-by: Don Brace <don.brace@pmcs.com>
Signed-off-by: Stephen M. Cameron <stephenmcameron@gmail.com>
Reviewed-by: Joe Handzik <joseph.t.handzik@hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index f028ae4a04be1ed852054258f765a371d33a2699..c079bb94f86b209d453eb619197052f4a8d83691 100644 (file)
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -394,7 +394,8 @@ static ssize_t host_show_commands_outstanding(struct device *dev,
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ctlr_info *h = shost_to_hba(shost);
 
-       return snprintf(buf, 20, "%d\n", h->commands_outstanding);
+       return snprintf(buf, 20, "%d\n",
+                       atomic_read(&h->commands_outstanding));
 }
 
 static ssize_t host_show_transport_mode(struct device *dev,
@@ -700,7 +701,6 @@ static inline u32 next_command(struct ctlr_info *h, u8 q)
 {
        u32 a;
        struct reply_queue_buffer *rq = &h->reply_queue[q];
-       unsigned long flags;
 
        if (h->transMethod & CFGTBL_Trans_io_accel1)
                return h->access.command_completed(h, q);
@@ -711,9 +711,7 @@ static inline u32 next_command(struct ctlr_info *h, u8 q)
        if ((rq->head[rq->current_entry] & 1) == rq->wraparound) {
                a = rq->head[rq->current_entry];
                rq->current_entry++;
-               spin_lock_irqsave(&h->lock, flags);
-               h->commands_outstanding--;
-               spin_unlock_irqrestore(&h->lock, flags);
+               atomic_dec(&h->commands_outstanding);
        } else {
                a = FIFO_EMPTY;
        }
@@ -5445,15 +5443,9 @@ static void start_io(struct ctlr_info *h, unsigned long *flags)
 
                /* Put job onto the completed Q */
                addQ(&h->cmpQ, c);
-
-               /* Must increment commands_outstanding before unlocking
-                * and submitting to avoid race checking for fifo full
-                * condition.
-                */
-               h->commands_outstanding++;
-
-               /* Tell the controller execute command */
+               atomic_inc(&h->commands_outstanding);
                spin_unlock_irqrestore(&h->lock, *flags);
+               /* Tell the controller execute command */
                h->access.submit_command(h, c);
                spin_lock_irqsave(&h->lock, *flags);
        }
@@ -5499,6 +5491,7 @@ static inline void finish_cmd(struct CommandList *c)
        unsigned long flags;
        int io_may_be_stalled = 0;
        struct ctlr_info *h = c->h;
+       int count;
 
        spin_lock_irqsave(&h->lock, flags);
        removeQ(c);
@@ -5519,11 +5512,10 @@ static inline void finish_cmd(struct CommandList *c)
         * want to get in a cycle where we call start_io every time
         * through here.
         */
-       if (unlikely(h->fifo_recently_full) &&
-               h->commands_outstanding < 5)
-               io_may_be_stalled = 1;
-
+       count = atomic_read(&h->commands_outstanding);
        spin_unlock_irqrestore(&h->lock, flags);
+       if (unlikely(h->fifo_recently_full) && count < 5)
+               io_may_be_stalled = 1;
 
        dial_up_lockup_detection_on_fw_flash_complete(c->h, c);
        if (likely(c->cmd_type == CMD_IOACCEL1 || c->cmd_type == CMD_SCSI

diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index 80fa9a99b69250fcf0f1ba21f7e82f5395b7aa1f..8e06d9e280ec7dc033f3bf56e8c268393b6c3275 100644 (file)
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -118,7 +118,7 @@ struct ctlr_info {
        struct CfgTable __iomem *cfgtable;
        int     interrupts_enabled;
        int     max_commands;
-       int     commands_outstanding;
+       atomic_t commands_outstanding;
 #      define PERF_MODE_INT    0
 #      define DOORBELL_INT     1
 #      define SIMPLE_MODE_INT  2
@@ -395,7 +395,7 @@ static void SA5_performant_intr_mask(struct ctlr_info *h, unsigned long val)
 static unsigned long SA5_performant_completed(struct ctlr_info *h, u8 q)
 {
        struct reply_queue_buffer *rq = &h->reply_queue[q];
-       unsigned long flags, register_value = FIFO_EMPTY;
+       unsigned long register_value = FIFO_EMPTY;
 
        /* msi auto clears the interrupt pending bit. */
        if (!(h->msi_vector || h->msix_vector)) {
@@ -413,9 +413,7 @@ static unsigned long SA5_performant_completed(struct ctlr_info *h, u8 q)
        if ((rq->head[rq->current_entry] & 1) == rq->wraparound) {
                register_value = rq->head[rq->current_entry];
                rq->current_entry++;
-               spin_lock_irqsave(&h->lock, flags);
-               h->commands_outstanding--;
-               spin_unlock_irqrestore(&h->lock, flags);
+               atomic_dec(&h->commands_outstanding);
        } else {
                register_value = FIFO_EMPTY;
        }
@@ -433,11 +431,7 @@ static unsigned long SA5_performant_completed(struct ctlr_info *h, u8 q)
  */
 static unsigned long SA5_fifo_full(struct ctlr_info *h)
 {
-       if (h->commands_outstanding >= h->max_commands)
-               return 1;
-       else
-               return 0;
-
+       return atomic_read(&h->commands_outstanding) >= h->max_commands;
 }
 /*
  *   returns value read from hardware.
@@ -448,13 +442,9 @@ static unsigned long SA5_completed(struct ctlr_info *h,
 {
        unsigned long register_value
                = readl(h->vaddr + SA5_REPLY_PORT_OFFSET);
-       unsigned long flags;
 
-       if (register_value != FIFO_EMPTY) {
-               spin_lock_irqsave(&h->lock, flags);
-               h->commands_outstanding--;
-               spin_unlock_irqrestore(&h->lock, flags);
-       }
+       if (register_value != FIFO_EMPTY)
+               atomic_dec(&h->commands_outstanding);
 
 #ifdef HPSA_DEBUG
        if (register_value != FIFO_EMPTY)
@@ -510,7 +500,6 @@ static unsigned long SA5_ioaccel_mode1_completed(struct ctlr_info *h, u8 q)
 {
        u64 register_value;
        struct reply_queue_buffer *rq = &h->reply_queue[q];
-       unsigned long flags;
 
        BUG_ON(q >= h->nreply_queues);
 
@@ -528,9 +517,7 @@ static unsigned long SA5_ioaccel_mode1_completed(struct ctlr_info *h, u8 q)
                wmb();
                writel((q << 24) | rq->current_entry, h->vaddr +
                                IOACCEL_MODE1_CONSUMER_INDEX);
-               spin_lock_irqsave(&h->lock, flags);
-               h->commands_outstanding--;
-               spin_unlock_irqrestore(&h->lock, flags);
+               atomic_dec(&h->commands_outstanding);
        }
        return (unsigned long) register_value;
 }