[ 118/122] mmc: sh-mmcif: avoid oops on spurious interrupts

[Greg Kroah-Hartman]

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>

commit 8464dd52d3198dd05cafb005371d76e5339eb842 upstream.

On some systems, e.g., kzm9g, MMCIF interfaces can produce spurious
interrupts without any active request. To prevent the Oops, that results
in such cases, don't dereference the mmc request pointer until we make
sure, that we are indeed processing such a request.

Reported-by: Tetsuyuki Kobayashi <koba@xxxxxxxxxxx>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
Signed-off-by: Chris Ball <cjb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mmc/host/sh_mmcif.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -1229,6 +1229,10 @@ static irqreturn_t sh_mmcif_intr(int irq
 		host->sd_error = true;
 		dev_dbg(&host->pd->dev, "int err state = %08x\n", state);
 	}
+	if (host->state == STATE_IDLE) {
+		dev_info(&host->pd->dev, "Spurious IRQ status 0x%x", state);
+		return IRQ_HANDLED;
+	}
 	if (state & ~(INT_CMD12RBE | INT_CMD12CRE)) {
 		if (!host->dma_active)
 			return IRQ_WAKE_THREAD;


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