Re: [PATCH] dmaengine: shdma: fix a race condition in __ld_cleanup()

[Vinod Koul <vinod.koul@intel.com>]

On Thu, Oct 09, 2014 at 11:09:00AM +0900, Yoshihiro Shimoda wrote:
> This patch fixes a race condition about a list of shdma-base driver.
> If we don't apply this patch, a dma slave driver (especially a usb
> peripheral driver) may not be able to start the transfer.
> 
> If a dma slave driver has a callback, __ld_cleanup() will call
> the callback before this driver removes the list. After the callback,
> since the return value of __ld_cleanup() is not zero,
> shdma_chan_ld_cleanup() calls __ld_cleanup() again. And, __ld_clean()
> will removes the list.
> 
> At this time, if a dma slave driver calls dmaengine_submit() before
> this driver removes the list, this driver will set schan->pm_state
> to SHDMA_PM_PENDING in shdma_tx_submit(). And then, even if a dma
> slave driver calls dma_async_issue_pending(), this driver don't
> start the transfer because the schan->pm_state is SHDMA_PM_PENDING
> in shdma_issue_pending().
> 
> So, this patch adds a new condition in __ld_clean() to check if the
> schan->pm_state is SHDMA_PM_PENDING or not.
Applied, thanks

-- 
~Vinod