]> bbs.cooldavid.org Git - net-next-2.6.git/blobdiff - drivers/dma/ioat/dma_v2.c
ioat: close potential BUG_ON race in the descriptor cleanup path
[net-next-2.6.git] / drivers / dma / ioat / dma_v2.c
index 8f1f7f05deaadaac6cd428cbef09e35e161ededc..01ed1cfd3eb6d159af7b560c8a7419e4305ba67c 100644 (file)
@@ -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)
@@ -166,7 +158,7 @@ static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete)
                        seen_current = true;
        }
        ioat->tail += i;
-       BUG_ON(!seen_current); /* no active descs have written a completion? */
+       BUG_ON(active && !seen_current); /* no active descs have written a completion? */
 
        chan->last_completion = phys_complete;
        if (ioat->head == ioat->tail) {
@@ -239,20 +231,50 @@ void __ioat2_restart_chan(struct ioat2_dma_chan *ioat)
                __ioat2_start_null_desc(ioat);
 }
 
-static void ioat2_restart_channel(struct ioat2_dma_chan *ioat)
+int ioat2_quiesce(struct ioat_chan_common *chan, unsigned long tmo)
 {
-       struct ioat_chan_common *chan = &ioat->base;
-       unsigned long phys_complete;
+       unsigned long end = jiffies + tmo;
+       int err = 0;
        u32 status;
 
        status = ioat_chansts(chan);
        if (is_ioat_active(status) || is_ioat_idle(status))
                ioat_suspend(chan);
        while (is_ioat_active(status) || is_ioat_idle(status)) {
+               if (end && time_after(jiffies, end)) {
+                       err = -ETIMEDOUT;
+                       break;
+               }
                status = ioat_chansts(chan);
                cpu_relax();
        }
 
+       return err;
+}
+
+int ioat2_reset_sync(struct ioat_chan_common *chan, unsigned long tmo)
+{
+       unsigned long end = jiffies + tmo;
+       int err = 0;
+
+       ioat_reset(chan);
+       while (ioat_reset_pending(chan)) {
+               if (end && time_after(jiffies, end)) {
+                       err = -ETIMEDOUT;
+                       break;
+               }
+               cpu_relax();
+       }
+
+       return err;
+}
+
+static void ioat2_restart_channel(struct ioat2_dma_chan *ioat)
+{
+       struct ioat_chan_common *chan = &ioat->base;
+       unsigned long phys_complete;
+
+       ioat2_quiesce(chan, 0);
        if (ioat_cleanup_preamble(chan, &phys_complete))
                __cleanup(ioat, phys_complete);
 
@@ -318,6 +340,19 @@ void ioat2_timer_event(unsigned long data)
        spin_unlock_bh(&chan->cleanup_lock);
 }
 
+static int ioat2_reset_hw(struct ioat_chan_common *chan)
+{
+       /* throw away whatever the channel was doing and get it initialized */
+       u32 chanerr;
+
+       ioat2_quiesce(chan, msecs_to_jiffies(100));
+
+       chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET);
+       writel(chanerr, chan->reg_base + IOAT_CHANERR_OFFSET);
+
+       return ioat2_reset_sync(chan, msecs_to_jiffies(200));
+}
+
 /**
  * ioat2_enumerate_channels - find and initialize the device's channels
  * @device: the device to be enumerated
@@ -360,6 +395,10 @@ int ioat2_enumerate_channels(struct ioatdma_device *device)
                                  (unsigned long) ioat);
                ioat->xfercap_log = xfercap_log;
                spin_lock_init(&ioat->ring_lock);
+               if (device->reset_hw(&ioat->base)) {
+                       i = 0;
+                       break;
+               }
        }
        dma->chancnt = i;
        return i;
@@ -467,7 +506,6 @@ int ioat2_alloc_chan_resources(struct dma_chan *c)
        struct ioat2_dma_chan *ioat = to_ioat2_chan(c);
        struct ioat_chan_common *chan = &ioat->base;
        struct ioat_ring_ent **ring;
-       u32 chanerr;
        int order;
 
        /* have we already been set up? */
@@ -477,12 +515,6 @@ int ioat2_alloc_chan_resources(struct dma_chan *c)
        /* Setup register to interrupt and write completion status on error */
        writew(IOAT_CHANCTRL_RUN, chan->reg_base + IOAT_CHANCTRL_OFFSET);
 
-       chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET);
-       if (chanerr) {
-               dev_err(to_dev(chan), "CHANERR = %x, clearing\n", chanerr);
-               writel(chanerr, chan->reg_base + IOAT_CHANERR_OFFSET);
-       }
-
        /* allocate a completion writeback area */
        /* doing 2 32bit writes to mmio since 1 64b write doesn't work */
        chan->completion = pci_pool_alloc(chan->device->completion_pool,
@@ -506,7 +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);
 
@@ -746,13 +777,7 @@ void ioat2_free_chan_resources(struct dma_chan *c)
        tasklet_disable(&chan->cleanup_task);
        del_timer_sync(&chan->timer);
        device->cleanup_tasklet((unsigned long) ioat);
-
-       /* Delay 100ms after reset to allow internal DMA logic to quiesce
-        * before removing DMA descriptor resources.
-        */
-       writeb(IOAT_CHANCMD_RESET,
-              chan->reg_base + IOAT_CHANCMD_OFFSET(chan->device->version));
-       mdelay(100);
+       device->reset_hw(chan);
 
        spin_lock_bh(&ioat->ring_lock);
        descs = ioat2_ring_space(ioat);
@@ -781,7 +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;
 }
 
@@ -839,6 +863,7 @@ int __devinit ioat2_dma_probe(struct ioatdma_device *device, int dca)
        int err;
 
        device->enumerate_channels = ioat2_enumerate_channels;
+       device->reset_hw = ioat2_reset_hw;
        device->cleanup_tasklet = ioat2_cleanup_tasklet;
        device->timer_fn = ioat2_timer_event;
        device->self_test = ioat_dma_self_test;