dmaengine: idxd: add work queue drain support

Add wq drain support. When a wq is being released, it needs to wait for
all in-flight operation to complete.  A device control function
idxd_wq_drain() has been added to facilitate this. A wq drain call
is added to the char dev on release to make sure all user operations are
complete. A wq drain is also added before the wq is being disabled.

A drain command can take an unpredictable period of time. Interrupt support
for device commands is added to allow waiting on the command to
finish. If a previous command is in progress, the new submitter can block
until the current command is finished before proceeding. The interrupt
based submission will submit the command and then wait until a command
completion interrupt happens to complete. All commands are moved to the
interrupt based command submission except for the device reset during
probe, which will be polled.

Fixes: 42d279f9137a ("dmaengine: idxd: add char driver to expose submission portal to userland")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/159319502515.69593.13451647706946040301.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 19 insertions, 22 deletions

diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
index 6510791b9921..6052765ca3c8 100644
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -23,16 +23,13 @@ void idxd_device_wqs_clear_state(struct idxd_device *idxd)
 	}
 }
 
-static int idxd_restart(struct idxd_device *idxd)
+static void idxd_device_reinit(struct work_struct *work)
 {
-	int i, rc;
-
-	lockdep_assert_held(&idxd->dev_lock);
-
-	rc = __idxd_device_reset(idxd);
-	if (rc < 0)
-		goto out;
+	struct idxd_device *idxd = container_of(work, struct idxd_device, work);
+	struct device *dev = &idxd->pdev->dev;
+	int rc, i;
 
+	idxd_device_reset(idxd);
 	rc = idxd_device_config(idxd);
 	if (rc < 0)
 		goto out;
@@ -47,19 +44,16 @@ static int idxd_restart(struct idxd_device *idxd)
 		if (wq->state == IDXD_WQ_ENABLED) {
 			rc = idxd_wq_enable(wq);
 			if (rc < 0) {
-				dev_warn(&idxd->pdev->dev,
-					 "Unable to re-enable wq %s\n",
+				dev_warn(dev, "Unable to re-enable wq %s\n",
 					 dev_name(&wq->conf_dev));
 			}
 		}
 	}
 
-	return 0;
+	return;
 
  out:
 	idxd_device_wqs_clear_state(idxd);
-	idxd->state = IDXD_DEV_HALTED;
-	return rc;
 }
 
 irqreturn_t idxd_irq_handler(int vec, void *data)
@@ -78,7 +72,7 @@ irqreturn_t idxd_misc_thread(int vec, void *data)
 	struct device *dev = &idxd->pdev->dev;
 	union gensts_reg gensts;
 	u32 cause, val = 0;
-	int i, rc;
+	int i;
 	bool err = false;
 
 	cause = ioread32(idxd->reg_base + IDXD_INTCAUSE_OFFSET);
@@ -117,8 +111,8 @@ irqreturn_t idxd_misc_thread(int vec, void *data)
 	}
 
 	if (cause & IDXD_INTC_CMD) {
-		/* Driver does use command interrupts */
 		val |= IDXD_INTC_CMD;
+		complete(idxd->cmd_done);
 	}
 
 	if (cause & IDXD_INTC_OCCUPY) {
@@ -145,21 +139,24 @@ irqreturn_t idxd_misc_thread(int vec, void *data)
 
 	gensts.bits = ioread32(idxd->reg_base + IDXD_GENSTATS_OFFSET);
 	if (gensts.state == IDXD_DEVICE_STATE_HALT) {
-		spin_lock_bh(&idxd->dev_lock);
+		idxd->state = IDXD_DEV_HALTED;
 		if (gensts.reset_type == IDXD_DEVICE_RESET_SOFTWARE) {
-			rc = idxd_restart(idxd);
-			if (rc < 0)
-				dev_err(&idxd->pdev->dev,
-					"idxd restart failed, device halt.");
+			/*
+			 * If we need a software reset, we will throw the work
+			 * on a system workqueue in order to allow interrupts
+			 * for the device command completions.
+			 */
+			INIT_WORK(&idxd->work, idxd_device_reinit);
+			queue_work(idxd->wq, &idxd->work);
 		} else {
+			spin_lock_bh(&idxd->dev_lock);
 			idxd_device_wqs_clear_state(idxd);
-			idxd->state = IDXD_DEV_HALTED;
 			dev_err(&idxd->pdev->dev,
 				"idxd halted, need %s.\n",
 				gensts.reset_type == IDXD_DEVICE_RESET_FLR ?
 				"FLR" : "system reset");
+			spin_unlock_bh(&idxd->dev_lock);
 		}
-		spin_unlock_bh(&idxd->dev_lock);
 	}
 
 	idxd_unmask_msix_vector(idxd, irq_entry->id);