[PATCH] ARM: 2694/1: [s3c2410/dma] release irq properly to fix kernel oops

Patch from Albrecht Dreß

Problem:
When a module requests a DMA channel via the function s3c2410_dma_request(), this function requests the appropriate irq under the name of the client module. When the client module is unloaded, it calls s3c2410_dma_free() which does not free the irq. Consequently, when e.g. running "cat /proc/interrupts", the irq owner points to freed memory, leading to a kernel oops.
File:
linux/arch/arm/mach-s3c2410/dma.c
Fix:
trivial, below

Signed-off-by: Albrecht Dreß
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/arm/mach-s3c2410/dma.c b/arch/arm/mach-s3c2410/dma.c
index bc229fab86d..c7c28890d40 100644
--- a/arch/arm/mach-s3c2410/dma.c
+++ b/arch/arm/mach-s3c2410/dma.c
@@ -785,6 +785,10 @@ int s3c2410_dma_free(dmach_t channel, s3c2410_dma_client_t *client)
         chan->client = NULL;
         chan->in_use = 0;
 
+        if (chan->irq_claimed)
+                free_irq(chan->irq, (void *)chan);
+        chan->irq_claimed = 0;
+
         local_irq_restore(flags);
 
         return 0;