3.2.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Linus Walleij <linus.walleij@xxxxxxxxxx> commit e9baa9d9d520fb0e24cca671e430689de2d4a4b2 upstream. It appears that in the DMA40 driver the DMA tasklet will very often dereference memory for a descriptor just free:d from the DMA40 slab. Nothing happens because no other part of the driver has yet had a chance to claim this memory, but it's really nasty to dereference free:d memory, so let's check the flag before the descriptor is free and store it in a bool variable. Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- drivers/dma/ste_dma40.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/dma/ste_dma40.c +++ b/drivers/dma/ste_dma40.c @@ -1202,6 +1202,7 @@ static void dma_tasklet(unsigned long da struct d40_chan *d40c = (struct d40_chan *) data; struct d40_desc *d40d; unsigned long flags; + bool callback_active; dma_async_tx_callback callback; void *callback_param; @@ -1225,6 +1226,7 @@ static void dma_tasklet(unsigned long da } /* Callback to client */ + callback_active = !!(d40d->txd.flags & DMA_PREP_INTERRUPT); callback = d40d->txd.callback; callback_param = d40d->txd.callback_param; @@ -1249,7 +1251,7 @@ static void dma_tasklet(unsigned long da spin_unlock_irqrestore(&d40c->lock, flags); - if (callback && (d40d->txd.flags & DMA_PREP_INTERRUPT)) + if (callback_active && callback) callback(callback_param); return; -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html