I/OAT: watchdog/reset and tcp_dma_copybreak

index 318e8a2..9c0b90a 100644
@@ -32,6 +32,7 @@ #include <linux/interrupt.h>
 #include <linux/dmaengine.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
+#include <linux/workqueue.h>
 #include "ioatdma.h"
 #include "ioatdma_registers.h"
 #include "ioatdma_hw.h"

@@ -41,11 +42,17 @@ #define to_ioatdma_device(dev) container
 #define to_ioat_desc(lh) container_of(lh, struct ioat_desc_sw, node)
 #define tx_to_ioat_desc(tx) container_of(tx, struct ioat_desc_sw, async_tx)
 
+#define chan_num(ch) ((int)((ch)->reg_base - (ch)->device->reg_base) / 0x80)
 static int ioat_pending_level = 4;
 module_param(ioat_pending_level, int, 0644);
 MODULE_PARM_DESC(ioat_pending_level,
 		 "high-water mark for pushing ioat descriptors (default: 4)");
 
+#define RESET_DELAY  msecs_to_jiffies(100)
+#define WATCHDOG_DELAY  round_jiffies(msecs_to_jiffies(2000))
+static void ioat_dma_chan_reset_part2(struct work_struct *work);
+static void ioat_dma_chan_watchdog(struct work_struct *work);
+
 /* internal functions */
 static void ioat_dma_start_null_desc(struct ioat_dma_chan *ioat_chan);
 static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *ioat_chan);

@@ -137,6 +144,7 @@ static int ioat_dma_enumerate_channels(s
 		ioat_chan->reg_base = device->reg_base + (0x80 * (i + 1));
 		ioat_chan->xfercap = xfercap;
 		ioat_chan->desccount = 0;
+		INIT_DELAYED_WORK(&ioat_chan->work, ioat_dma_chan_reset_part2);
 		if (ioat_chan->device->version != IOAT_VER_1_2) {
 			writel(IOAT_DCACTRL_CMPL_WRITE_ENABLE
 					| IOAT_DMA_DCA_ANY_CPU,

@@ -175,7 +183,7 @@ static void ioat1_dma_memcpy_issue_pendi
 {
 	struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
 
-	if (ioat_chan->pending != 0) {
+	if (ioat_chan->pending > 0) {
 		spin_lock_bh(&ioat_chan->desc_lock);
 		__ioat1_dma_memcpy_issue_pending(ioat_chan);
 		spin_unlock_bh(&ioat_chan->desc_lock);

@@ -194,13 +202,218 @@ static void ioat2_dma_memcpy_issue_pendi
 {
 	struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
 
-	if (ioat_chan->pending != 0) {
+	if (ioat_chan->pending > 0) {
 		spin_lock_bh(&ioat_chan->desc_lock);
 		__ioat2_dma_memcpy_issue_pending(ioat_chan);
 		spin_unlock_bh(&ioat_chan->desc_lock);
 	}
 }
 
+
+/**
+ * ioat_dma_chan_reset_part2 - reinit the channel after a reset
+ */
+static void ioat_dma_chan_reset_part2(struct work_struct *work) 
+{
+	struct ioat_dma_chan *ioat_chan = container_of(work, struct ioat_dma_chan, work.work);
+	struct ioat_desc_sw *desc;
+
+	spin_lock_bh(&ioat_chan->cleanup_lock);
+	spin_lock_bh(&ioat_chan->desc_lock);
+
+	ioat_chan->completion_virt->low = 0;
+	ioat_chan->completion_virt->high = 0;
+	ioat_chan->pending = 0;
+
+	/*
+	 * count the descriptors waiting, and be sure to do it
+	 * right for both the CB1 line and the CB2 ring
+	 */
+	ioat_chan->dmacount = 0;
+	if (ioat_chan->used_desc.prev) {
+		desc = to_ioat_desc(ioat_chan->used_desc.prev);
+		do {
+			ioat_chan->dmacount++;
+			desc = to_ioat_desc(desc->node.next);
+		} while (&desc->node != ioat_chan->used_desc.next);
+	}
+
+	/*
+	 * write the new starting descriptor address
+	 * this puts channel engine into ARMED state
+	 */
+	desc = to_ioat_desc(ioat_chan->used_desc.prev);
+	switch (ioat_chan->device->version) {
+	case IOAT_VER_1_2:
+		writel(((u64) desc->async_tx.phys) & 0x00000000FFFFFFFF,
+		       ioat_chan->reg_base + IOAT1_CHAINADDR_OFFSET_LOW);
+		writel(((u64) desc->async_tx.phys) >> 32,
+		       ioat_chan->reg_base + IOAT1_CHAINADDR_OFFSET_HIGH);
+
+		writeb(IOAT_CHANCMD_START, ioat_chan->reg_base
+			+ IOAT_CHANCMD_OFFSET(ioat_chan->device->version));
+		break;
+	case IOAT_VER_2_0:
+		writel(((u64) desc->async_tx.phys) & 0x00000000FFFFFFFF,
+		       ioat_chan->reg_base + IOAT2_CHAINADDR_OFFSET_LOW);
+		writel(((u64) desc->async_tx.phys) >> 32,
+		       ioat_chan->reg_base + IOAT2_CHAINADDR_OFFSET_HIGH);
+
+		/* tell the engine to go with what's left to be done */
+		writew(ioat_chan->dmacount,
+		       ioat_chan->reg_base + IOAT_CHAN_DMACOUNT_OFFSET);
+
+		break;
+	}
+	dev_err(&ioat_chan->device->pdev->dev,
+		"chan%d reset - %d descs waiting, %d total desc\n",
+		chan_num(ioat_chan), ioat_chan->dmacount, ioat_chan->desccount);
+
+	spin_unlock_bh(&ioat_chan->desc_lock);
+	spin_unlock_bh(&ioat_chan->cleanup_lock);
+}
+
+/**
+ * ioat_dma_reset_channel - restart a channel
+ * @ioat_chan: IOAT DMA channel handle
+ */
+static void ioat_dma_reset_channel(struct ioat_dma_chan *ioat_chan)
+{
+	u32 chansts, chanerr;
+
+	if (!ioat_chan->used_desc.prev)
+		return;
+
+	chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
+	chansts = (ioat_chan->completion_virt->low
+					& IOAT_CHANSTS_DMA_TRANSFER_STATUS);
+	if (chanerr) {
+		dev_err(&ioat_chan->device->pdev->dev,
+			"chan%d, CHANSTS = 0x%08x CHANERR = 0x%04x, clearing\n",
+			chan_num(ioat_chan), chansts, chanerr);
+		writel(chanerr, ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
+	}
+
+	/*
+	 * whack it upside the head with a reset
+	 * and wait for things to settle out.
+	 * force the pending count to a really big negative
+	 * to make sure no one forces an issue_pending
+	 * while we're waiting.
+	 */
+
+	spin_lock_bh(&ioat_chan->desc_lock);
+	ioat_chan->pending = INT_MIN;
+	writeb(IOAT_CHANCMD_RESET,
+	       ioat_chan->reg_base
+	       + IOAT_CHANCMD_OFFSET(ioat_chan->device->version));
+	spin_unlock_bh(&ioat_chan->desc_lock);
+
+	/* schedule the 2nd half instead of sleeping a long time */
+	schedule_delayed_work(&ioat_chan->work, RESET_DELAY);
+}
+
+/**
+ * ioat_dma_chan_watchdog - watch for stuck channels
+ */
+static void ioat_dma_chan_watchdog(struct work_struct *work)
+{
+	struct ioatdma_device *device = container_of(work, struct ioatdma_device, work.work);
+	struct ioat_dma_chan *ioat_chan;
+	int i;
+
+	union {
+		u64 full;
+		struct {
+			u32 low;
+			u32 high;
+		};
+	} completion_hw;
+	unsigned long compl_desc_addr_hw;
+
+	for (i = 0; i < device->common.chancnt; i++) {
+		ioat_chan = ioat_lookup_chan_by_index(device, i);
+
+		if (ioat_chan->device->version == IOAT_VER_1_2
+			/* have we started processing anything yet */
+		    && ioat_chan->last_completion
+			/* have we completed any since last watchdog cycle? */
+		    && (ioat_chan->last_completion == ioat_chan->watchdog_completion)
+			/* has TCP stuck on one cookie since last watchdog? */
+		    && (ioat_chan->watchdog_tcp_cookie == ioat_chan->watchdog_last_tcp_cookie)
+		    && (ioat_chan->watchdog_tcp_cookie != ioat_chan->completed_cookie)
+			/* is there something in the chain to be processed? */
+			/* CB1 chain always has at least the last one processed */
+		    && (ioat_chan->used_desc.prev != ioat_chan->used_desc.next)
+		    && ioat_chan->pending == 0) {
+
+			/*
+			 * check CHANSTS register for completed descriptor address
+			 * if it is different than completion writeback, it is not zero 
+			 * and it has changed since the last watchdog
+			 *     we can assume that channel is still working correctly 
+			 *     and the problem is in completion writeback.
+			 *     update completion writeback with actual CHANSTS value
+			 * else
+			 *     try resetting the channel
+			 */
+
+			completion_hw.low = readl(ioat_chan->reg_base + 
+				IOAT_CHANSTS_OFFSET_LOW(ioat_chan->device->version));
+			completion_hw.high = readl(ioat_chan->reg_base + 
+				IOAT_CHANSTS_OFFSET_HIGH(ioat_chan->device->version));
+#if (BITS_PER_LONG == 64)
+			compl_desc_addr_hw =
+				completion_hw.full
+				& IOAT_CHANSTS_COMPLETED_DESCRIPTOR_ADDR;
+#else
+			compl_desc_addr_hw =
+				completion_hw.low & IOAT_LOW_COMPLETION_MASK;
+#endif
+
+			if((compl_desc_addr_hw != 0)
+			   && (compl_desc_addr_hw != ioat_chan->watchdog_completion)
+			   && (compl_desc_addr_hw != ioat_chan->last_compl_desc_addr_hw)) {
+				ioat_chan->last_compl_desc_addr_hw = compl_desc_addr_hw;
+				ioat_chan->completion_virt->low = completion_hw.low;
+				ioat_chan->completion_virt->high = completion_hw.high;
+			} else {
+				ioat_dma_reset_channel(ioat_chan);
+				ioat_chan->watchdog_completion = 0;
+				ioat_chan->last_compl_desc_addr_hw = 0;
+			}
+
+		/*
+		 * for version 2.0 if there are descriptors yet to be processed
+		 * and the last completed hasn't changed since the last watchdog
+		 *      if they haven't hit the pending level
+		 *          issue the pending to push them through
+		 *      else
+		 *          try resetting the channel
+		 */
+		} else if (ioat_chan->device->version == IOAT_VER_2_0
+		    && ioat_chan->used_desc.prev
+		    && ioat_chan->last_completion
+		    && ioat_chan->last_completion == ioat_chan->watchdog_completion) {
+
+			if (ioat_chan->pending < ioat_pending_level)
+				ioat2_dma_memcpy_issue_pending(&ioat_chan->common);
+			else {
+				ioat_dma_reset_channel(ioat_chan);
+				ioat_chan->watchdog_completion = 0;
+			}
+		} else {
+			ioat_chan->last_compl_desc_addr_hw = 0;
+			ioat_chan->watchdog_completion
+					= ioat_chan->last_completion;
+		}
+
+		ioat_chan->watchdog_last_tcp_cookie = ioat_chan->watchdog_tcp_cookie;
+	}
+
+	schedule_delayed_work(&device->work, WATCHDOG_DELAY);
+}
+
 static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx)
 {
 	struct ioat_dma_chan *ioat_chan = to_ioat_chan(tx->chan);

@@ -585,6 +798,9 @@ static void ioat_dma_free_chan_resources
 	ioat_chan->last_completion = ioat_chan->completion_addr = 0;
 	ioat_chan->pending = 0;
 	ioat_chan->dmacount = 0;
+	ioat_chan->watchdog_completion = 0;
+	ioat_chan->last_compl_desc_addr_hw = 0;
+	ioat_chan->watchdog_tcp_cookie = ioat_chan->watchdog_last_tcp_cookie = 0;
 }
 
 /**

@@ -716,8 +932,12 @@ static struct dma_async_tx_descriptor *i
 		new->src = dma_src;
 		new->async_tx.flags = flags;
 		return &new->async_tx;
-	} else
+	} else {
+		dev_err(&ioat_chan->device->pdev->dev,
+			"chan%d - get_next_desc failed: %d descs waiting, %d total desc\n",
+			chan_num(ioat_chan), ioat_chan->dmacount, ioat_chan->desccount);
 		return NULL;
+	}
 }
 
 static struct dma_async_tx_descriptor *ioat2_dma_prep_memcpy(

@@ -744,8 +964,13 @@ static struct dma_async_tx_descriptor *i
 		new->src = dma_src;
 		new->async_tx.flags = flags;
 		return &new->async_tx;
-	} else
+	} else {
+		spin_unlock_bh(&ioat_chan->desc_lock);
+		dev_err(&ioat_chan->device->pdev->dev,
+			"chan%d - get_next_desc failed: %d descs waiting, %d total desc\n",
+			chan_num(ioat_chan), ioat_chan->dmacount, ioat_chan->desccount);
 		return NULL;
+	}
 }
 
 static void ioat_dma_cleanup_tasklet(unsigned long data)

@@ -799,11 +1024,25 @@ #endif
 
 	if (phys_complete == ioat_chan->last_completion) {
 		spin_unlock_bh(&ioat_chan->cleanup_lock);
+		/*
+		 * perhaps we're stuck so hard that the watchdog can't go off?
+		 * try to catch it after 2 seconds
+		 */
+		if (time_after(jiffies, 
+			       ioat_chan->last_completion_time + HZ*WATCHDOG_DELAY)) {
+			ioat_dma_chan_watchdog(&(ioat_chan->device->work.work));
+			ioat_chan->last_completion_time = jiffies;
+		}
 		return;
 	}
+	ioat_chan->last_completion_time = jiffies;
 
 	cookie = 0;
-	spin_lock_bh(&ioat_chan->desc_lock);
+	if (!spin_trylock_bh(&ioat_chan->desc_lock)) {
+		spin_unlock_bh(&ioat_chan->cleanup_lock);
+		return;
+	}
+
 	switch (ioat_chan->device->version) {
 	case IOAT_VER_1_2:
 		list_for_each_entry_safe(desc, _desc,

@@ -943,6 +1182,7 @@ static enum dma_status ioat_dma_is_compl
 
 	last_used = chan->cookie;
 	last_complete = ioat_chan->completed_cookie;
+	ioat_chan->watchdog_tcp_cookie = cookie;
 
 	if (done)
 		*done = last_complete;

@@ -1080,7 +1320,7 @@ static int ioat_dma_self_test(struct ioa
 		goto free_resources;
 	}
 	device->common.device_issue_pending(dma_chan);
-	msleep(1);
+	msleep(10);
 
 	if (device->common.device_is_tx_complete(dma_chan, cookie, NULL, NULL)
 					!= DMA_SUCCESS) {

@@ -1333,6 +1573,10 @@ struct ioatdma_device *ioat_dma_probe(st
 
 	dma_async_device_register(&device->common);
 
+	INIT_DELAYED_WORK(&device->work, ioat_dma_chan_watchdog);
+	schedule_delayed_work(&device->work,
+			      WATCHDOG_DELAY);
+
 	return device;
 
 err_self_test:

@@ -1365,6 +1609,8 @@ void ioat_dma_remove(struct ioatdma_devi
 	pci_release_regions(device->pdev);
 	pci_disable_device(device->pdev);
 
+	cancel_delayed_work(&device->work);
+
 	list_for_each_entry_safe(chan, _chan,
 				 &device->common.channels, device_node) {
 		ioat_chan = to_ioat_chan(chan);

index f2c7fed..c6ec933 100644
@@ -28,7 +28,7 @@ #include <linux/dmapool.h>
 #include <linux/cache.h>
 #include <linux/pci_ids.h>
 
-#define IOAT_DMA_VERSION  "2.04"
+#define IOAT_DMA_VERSION  "2.18"
 
 enum ioat_interrupt {
 	none = 0,

@@ -40,6 +40,7 @@ enum ioat_interrupt {
 
 #define IOAT_LOW_COMPLETION_MASK	0xffffffc0
 #define IOAT_DMA_DCA_ANY_CPU		~0
+#define IOAT_WATCHDOG_PERIOD		(2 * HZ)
 
 
 /**

@@ -62,6 +63,7 @@ struct ioatdma_device {
 	struct dma_device common;
 	u8 version;
 	enum ioat_interrupt irq_mode;
+	struct delayed_work work;
 	struct msix_entry msix_entries[4];
 	struct ioat_dma_chan *idx[4];
 };

@@ -75,6 +77,7 @@ struct ioat_dma_chan {
 
 	dma_cookie_t completed_cookie;
 	unsigned long last_completion;
+	unsigned long last_completion_time;
 
 	size_t xfercap;	/* XFERCAP register value expanded out */
 

@@ -82,6 +85,10 @@ struct ioat_dma_chan {
 	spinlock_t desc_lock;
 	struct list_head free_desc;
 	struct list_head used_desc;
+	unsigned long watchdog_completion;
+	int watchdog_tcp_cookie;
+	u32 watchdog_last_tcp_cookie;
+	struct delayed_work work;
 
 	int pending;
 	int dmacount;

@@ -98,6 +105,7 @@ struct ioat_dma_chan {
 			u32 high;
 		};
 	} *completion_virt;
+	unsigned long last_compl_desc_addr_hw;
 	struct tasklet_struct cleanup_task;
 };
 

index 97b329e..d57365a 100644
@@ -70,6 +70,7 @@ #include <linux/percpu.h>
 #include <linux/rcupdate.h>
 #include <linux/mutex.h>
 #include <linux/jiffies.h>
+#include <net/tcp.h>
 
 static DEFINE_MUTEX(dma_list_mutex);
 static LIST_HEAD(dma_device_list);

@@ -402,6 +403,8 @@ int dma_async_device_register(struct dma
 	list_add_tail(&device->global_node, &dma_device_list);
 	mutex_unlock(&dma_list_mutex);
 
+	sysctl_tcp_dma_copybreak = device->tcp_dma_copybreak;
+
 	dma_clients_notify_available();
 
 	return 0;

index 9c0b90a..42e5bfb 100644
@@ -53,6 +53,12 @@ #define WATCHDOG_DELAY  round_jiffies(ms
 static void ioat_dma_chan_reset_part2(struct work_struct *work);
 static void ioat_dma_chan_watchdog(struct work_struct *work);
 
+/*
+ * default tcp_dma_copybreak values for different IOAT versions
+ */
+#define IOAT1_DEFAULT_TCP_DMA_COPYBREAK 4096
+#define IOAT2_DEFAULT_TCP_DMA_COPYBREAK 2048
+
 /* internal functions */
 static void ioat_dma_start_null_desc(struct ioat_dma_chan *ioat_chan);
 static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *ioat_chan);

@@ -1571,6 +1577,15 @@ struct ioatdma_device *ioat_dma_probe(st
 	if (err)
 		goto err_self_test;
 
+	switch (device->version) {
+	case IOAT_VER_1_2:
+		device->common.tcp_dma_copybreak = IOAT1_DEFAULT_TCP_DMA_COPYBREAK;
+		break;
+	case IOAT_VER_2_0:
+		device->common.tcp_dma_copybreak = IOAT2_DEFAULT_TCP_DMA_COPYBREAK;
+		break;
+	}
+
 	dma_async_device_register(&device->common);
 
 	INIT_DELAYED_WORK(&device->work, ioat_dma_chan_watchdog);

index d08a5c5..c09128e 100644
@@ -251,6 +251,7 @@ struct dma_async_tx_descriptor {
  * @global_node: list_head for global dma_device_list
  * @cap_mask: one or more dma_capability flags
  * @max_xor: maximum number of xor sources, 0 if no capability
+ * @tcp_dma_copybreak: lower limit of TCP socket reads size offloaded by DMA 
  * @refcount: reference count
  * @done: IO completion struct
  * @dev_id: unique device ID

@@ -272,6 +273,7 @@ struct dma_device {
 	struct list_head global_node;
 	dma_cap_mask_t  cap_mask;
 	int max_xor;
+	int tcp_dma_copybreak;
 
 	struct kref refcount;
 	struct completion done;