Commit 4f302642 authored by Dave Jiang's avatar Dave Jiang Committed by Vinod Koul
Browse files

dmaengine: idxd: fix interrupt completion after unmasking 



The current implementation may miss completions after we unmask the
interrupt. In order to make sure we process all competions, we need to:
1. Do an MMIO read from the device as a barrier to ensure that all PCI
   writes for completions have arrived.
2. Check for any additional completions that we missed.

Fixes: 8f47d1a5 ("dmaengine: idxd: connect idxd to dmaengine subsystem")

Reported-by: default avatarSanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/158834641769.35613.1341160109892008587.stgit@djiang5-desk3.ch.intel.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent f8f482de

drivers/dma/idxd/device.c

+7 −0
Original line number Diff line number Diff line
@@ -62,6 +62,13 @@ int idxd_unmask_msix_vector(struct idxd_device *idxd, int vec_id) 
	perm.ignore = 0;

	iowrite32(perm.bits, idxd->reg_base + offset);



	/*

	 * A readback from the device ensures that any previously generated

	 * completion record writes are visible to software based on PCI

	 * ordering rules.

	 */

	perm.bits = ioread32(idxd->reg_base + offset);



	return 0;

}

drivers/dma/idxd/irq.c

+19 −7
Original line number Diff line number Diff line
@@ -173,6 +173,7 @@ static int irq_process_pending_llist(struct idxd_irq_entry *irq_entry, 
	struct llist_node *head;

	int queued = 0;



	*processed = 0;

	head = llist_del_all(&irq_entry->pending_llist);

	if (!head)

		return 0;
@@ -197,6 +198,7 @@ static int irq_process_work_list(struct idxd_irq_entry *irq_entry, 
	struct list_head *node, *next;

	int queued = 0;



	*processed = 0;

	if (list_empty(&irq_entry->work_list))

		return 0;
@@ -218,10 +220,9 @@ static int irq_process_work_list(struct idxd_irq_entry *irq_entry, 
	return queued;

}



irqreturn_t idxd_wq_thread(int irq, void *data)

static int idxd_desc_process(struct idxd_irq_entry *irq_entry)

{

	struct idxd_irq_entry *irq_entry = data;

	int rc, processed = 0, retry = 0;

	int rc, processed, total = 0;



	/*

	 * There are two lists we are processing. The pending_llist is where
@@ -244,15 +245,26 @@ irqreturn_t idxd_wq_thread(int irq, void *data) 
	 */

	do {

		rc = irq_process_work_list(irq_entry, &processed);

		if (rc != 0) {

			retry++;

		total += processed;

		if (rc != 0)

			continue;

		}



		rc = irq_process_pending_llist(irq_entry, &processed);

	} while (rc != 0 && retry != 10);

		total += processed;

	} while (rc != 0);



	return total;

}



irqreturn_t idxd_wq_thread(int irq, void *data)

{

	struct idxd_irq_entry *irq_entry = data;

	int processed;



	processed = idxd_desc_process(irq_entry);

	idxd_unmask_msix_vector(irq_entry->idxd, irq_entry->id);

	/* catch anything unprocessed after unmasking */

	processed += idxd_desc_process(irq_entry);



	if (processed == 0)

		return IRQ_NONE;

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