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Subject[PATCH] dmaengine: dw-edma: Check MSI descriptor before copying
Date
From: Alan Mikhak <alan.mikhak@sifive.com>

Modify dw_edma_irq_request() to check if a struct msi_desc entry exists
before copying the contents of its struct msi_msg pointer.

Without this sanity check, __get_cached_msi_msg() crashes when invoked by
dw_edma_irq_request() running on a Linux-based PCIe endpoint device. MSI
interrupt are not received by PCIe endpoint devices. If irq_get_msi_desc()
returns null, then there is no cached struct msi_msg to be copied.

This patch depends on the following patch:
[PATCH v2] dmaengine: dw-edma: Decouple dw-edma-core.c from struct pci_dev
https://patchwork.kernel.org/patch/11491757/

Signed-off-by: Alan Mikhak <alan.mikhak@sifive.com>
---
drivers/dma/dw-edma/dw-edma-core.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index db401eb11322..a5d15f6ed5eb 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -773,6 +773,7 @@ static int dw_edma_irq_request(struct dw_edma_chip *chip,
u32 rd_mask = 1;
int i, err = 0;
u32 ch_cnt;
+ int irq;

ch_cnt = dw->wr_ch_cnt + dw->rd_ch_cnt;

@@ -781,16 +782,16 @@ static int dw_edma_irq_request(struct dw_edma_chip *chip,

if (dw->nr_irqs == 1) {
/* Common IRQ shared among all channels */
- err = request_irq(dw->ops->irq_vector(dev, 0),
- dw_edma_interrupt_common,
+ irq = dw->ops->irq_vector(dev, 0);
+ err = request_irq(irq, dw_edma_interrupt_common,
IRQF_SHARED, dw->name, &dw->irq[0]);
if (err) {
dw->nr_irqs = 0;
return err;
}

- get_cached_msi_msg(dw->ops->irq_vector(dev, 0),
- &dw->irq[0].msi);
+ if (irq_get_msi_desc(irq))
+ get_cached_msi_msg(irq, &dw->irq[0].msi);
} else {
/* Distribute IRQs equally among all channels */
int tmp = dw->nr_irqs;
@@ -804,7 +805,8 @@ static int dw_edma_irq_request(struct dw_edma_chip *chip,
dw_edma_add_irq_mask(&rd_mask, *rd_alloc, dw->rd_ch_cnt);

for (i = 0; i < (*wr_alloc + *rd_alloc); i++) {
- err = request_irq(dw->ops->irq_vector(dev, i),
+ irq = dw->ops->irq_vector(dev, i);
+ err = request_irq(irq,
i < *wr_alloc ?
dw_edma_interrupt_write :
dw_edma_interrupt_read,
@@ -815,8 +817,8 @@ static int dw_edma_irq_request(struct dw_edma_chip *chip,
return err;
}

- get_cached_msi_msg(dw->ops->irq_vector(dev, i),
- &dw->irq[i].msi);
+ if (irq_get_msi_desc(irq))
+ get_cached_msi_msg(irq, &dw->irq[i].msi);
}

dw->nr_irqs = i;
--
2.7.4
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