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Message-Id: <20200608231211.3363633-159-sashal@kernel.org>
Date: Mon, 8 Jun 2020 19:04:44 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Dave Jiang <dave.jiang@...el.com>,
Sanjay Kumar <sanjay.k.kumar@...el.com>,
Vinod Koul <vkoul@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
dmaengine@...r.kernel.org
Subject: [PATCH AUTOSEL 5.6 159/606] dmaengine: idxd: fix interrupt completion after unmasking
From: Dave Jiang <dave.jiang@...el.com>
commit 4f302642b70c1348773fe7e3ded9fc315fa92990 upstream.
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: 8f47d1a5e545 ("dmaengine: idxd: connect idxd to dmaengine subsystem")
Reported-by: Sanjay Kumar <sanjay.k.kumar@...el.com>
Signed-off-by: Dave Jiang <dave.jiang@...el.com>
Link: https://lore.kernel.org/r/158834641769.35613.1341160109892008587.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/dma/idxd/device.c | 7 +++++++
drivers/dma/idxd/irq.c | 26 +++++++++++++++++++-------
2 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index f6f49f0f6fae..8d79a8787104 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -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;
}
diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
index d6fcd2e60103..6510791b9921 100644
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -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;
--
2.25.1
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