diff options
| author |   Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2014-09-29 20:06:45 +0200 |
|---|---|---|
| committer |   Vinod Koul <vinod.koul@intel.com> | 2014-10-15 20:55:04 +0530 |
| commit | 639559ada6194b722304fe267455b5bdf75c2f90 (patch) | |
| tree | 591b19fff5dd83dc097f6402cc927117fe5eafe6 /drivers/dma | |
| parent | dmaengine: dw: export probe()/remove() and Co to users (diff) | |
| download | linux-dev-639559ada6194b722304fe267455b5bdf75c2f90.tar.xz linux-dev-639559ada6194b722304fe267455b5bdf75c2f90.zip | |
dmaengine: edma: check for echan->edesc => NULL in edma_dma_pause()
I added book keeping of whether or not the 8250-dma driver has an RX
transfer pending or not so we don't BUG here if it calls
dmaengine_pause() on a channel which has not a pending transfer. Guess
what, this is not enough.
The following can be triggered with a busy RX channel and hackbench in
background:
- DMA transfer completes. The callback is delayed via
vchan_cookie_complete() into a tasklet so it das not happen asap.
- hackbench keeps the system busy so the tasklet does not run "soon".
- the UART collected enough data and generates an "timeout"-interrupt.
Since 8250-dma *thinks* the DMA-transfer is still pending it tries to
cancel it via invoking dmaengine_pause() first. This causes the segfault
because echan->edesc is NULL now that the transfer completed (however
the callback did not run yet).
With this patch we don't BUG in the scenario described.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/edma.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 7b65633f495e..123f578d6dd3 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -288,7 +288,7 @@ static int edma_slave_config(struct edma_chan *echan, static int edma_dma_pause(struct edma_chan *echan) { /* Pause/Resume only allowed with cyclic mode */ - if (!echan->edesc->cyclic) + if (!echan->edesc || !echan->edesc->cyclic) return -EINVAL; edma_pause(echan->ch_num); |