drv: be sure to have a DMA transfer descriptor

It happened at least once that we got an invalid tx pointer. Not sure why this happened (e.g. spurious interrupt?), but it happened. With this patch, we do not prevent this from happening, but we avoid to have a kernel crash. This could help to understand the real problem. Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

drv: be sure to have a DMA transfer descriptor
It happened at least once that we got an invalid tx pointer. Not sure why this happened (e.g. spurious interrupt?), but it happened. With this patch, we do not prevent this from happening, but we avoid to have a kernel crash. This could help to understand the real problem. Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
fee50359 · Federico Vaga · 210eb054 · fee50359
Commit fee50359 authored Apr 06, 2022 by Federico Vaga
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spec-gn412x-dma.c software/kernel/spec-gn412x-dma.c +5 -1

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--- a/software/kernel/spec-gn412x-dma.c
+++ b/software/kernel/spec-gn412x-dma.c
@@ -708,6 +708,10 @@ static irqreturn_t gn412x_dma_irq_handler(int irq, void *arg)

 	state = gn412x_dma_state(gn412x_dma);
 	gn412x_dma_schedule_next(chan);
+
+	if (WARN(!tx, "Invalid transfer descriptor\n"))
+	    goto out;
+
 	switch (state) {
 	case GN412X_DMA_STAT_IDLE:
 		dma_cookie_complete(&tx->tx);
@@ -740,7 +744,7 @@ static irqreturn_t gn412x_dma_irq_handler(int irq, void *arg)
 			state);
 		break;
 	}
-
+out:
 	/* Clean up memory */
 	gn412x_dma_tx_free(tx);