ioat2: kill pending flag

The pending == 2 case no longer exists in the driver so, we can use
ioat2_ring_pending() outside the lock to determine if there might be any
descriptors in the ring that the hardware has not seen.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c
index 5f7a500e18d02636f1b94650202f6b2614323bb7..c6e4531fe5240b6e453302946a12ceafbed20703 100644 (file)
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -51,48 +51,40 @@ MODULE_PARM_DESC(ioat_ring_max_alloc_order,
 
 void __ioat2_issue_pending(struct ioat2_dma_chan *ioat)
 {
-       void * __iomem reg_base = ioat->base.reg_base;
+       struct ioat_chan_common *chan = &ioat->base;
 
-       ioat->pending = 0;
        ioat->dmacount += ioat2_ring_pending(ioat);
        ioat->issued = ioat->head;
        /* make descriptor updates globally visible before notifying channel */
        wmb();
-       writew(ioat->dmacount, reg_base + IOAT_CHAN_DMACOUNT_OFFSET);
-       dev_dbg(to_dev(&ioat->base),
+       writew(ioat->dmacount, chan->reg_base + IOAT_CHAN_DMACOUNT_OFFSET);
+       dev_dbg(to_dev(chan),
                "%s: head: %#x tail: %#x issued: %#x count: %#x\n",
                __func__, ioat->head, ioat->tail, ioat->issued, ioat->dmacount);
 }
 
-void ioat2_issue_pending(struct dma_chan *chan)
+void ioat2_issue_pending(struct dma_chan *c)
 {
-       struct ioat2_dma_chan *ioat = to_ioat2_chan(chan);
+       struct ioat2_dma_chan *ioat = to_ioat2_chan(c);
 
-       spin_lock_bh(&ioat->ring_lock);
-       if (ioat->pending == 1)
+       if (ioat2_ring_pending(ioat)) {
+               spin_lock_bh(&ioat->ring_lock);
                __ioat2_issue_pending(ioat);
-       spin_unlock_bh(&ioat->ring_lock);
+               spin_unlock_bh(&ioat->ring_lock);
+       }
 }
 
 /**
  * ioat2_update_pending - log pending descriptors
  * @ioat: ioat2+ channel
  *
- * set pending to '1' unless pending is already set to '2', pending == 2
- * indicates that submission is temporarily blocked due to an in-flight
- * reset.  If we are already above the ioat_pending_level threshold then
- * just issue pending.
- *
- * called with ring_lock held
+ * Check if the number of unsubmitted descriptors has exceeded the
+ * watermark.  Called with ring_lock held
  */
 static void ioat2_update_pending(struct ioat2_dma_chan *ioat)
 {
-       if (unlikely(ioat->pending == 2))
-               return;
-       else if (ioat2_ring_pending(ioat) > ioat_pending_level)
+       if (ioat2_ring_pending(ioat) > ioat_pending_level)
                __ioat2_issue_pending(ioat);
-       else
-               ioat->pending = 1;
 }
 
 static void __ioat2_start_null_desc(struct ioat2_dma_chan *ioat)
@@ -546,7 +538,6 @@ int ioat2_alloc_chan_resources(struct dma_chan *c)
        ioat->head = 0;
        ioat->issued = 0;
        ioat->tail = 0;
-       ioat->pending = 0;
        ioat->alloc_order = order;
        spin_unlock_bh(&ioat->ring_lock);
 
@@ -815,7 +806,6 @@ void ioat2_free_chan_resources(struct dma_chan *c)
 
        chan->last_completion = 0;
        chan->completion_dma = 0;
-       ioat->pending = 0;
        ioat->dmacount = 0;
 }
 

diff --git a/drivers/dma/ioat/dma_v2.h b/drivers/dma/ioat/dma_v2.h
index 3afad8da43ccf1a71354fc2400cd7eca9beb2901..d211335b48f8b80cf484e383bd71b1ad1605e486 100644 (file)
--- a/drivers/dma/ioat/dma_v2.h
+++ b/drivers/dma/ioat/dma_v2.h
@@ -47,7 +47,6 @@ extern int ioat_ring_alloc_order;
  * @head: allocated index
  * @issued: hardware notification point
  * @tail: cleanup index
- * @pending: lock free indicator for issued != head
  * @dmacount: identical to 'head' except for occasionally resetting to zero
  * @alloc_order: log2 of the number of allocated descriptors
  * @ring: software ring buffer implementation of hardware ring
@@ -61,7 +60,6 @@ struct ioat2_dma_chan {
        u16 tail;
        u16 dmacount;
        u16 alloc_order;
-       int pending;
        struct ioat_ring_ent **ring;
        spinlock_t ring_lock;
 };