On 19.02.2016 15:39, Anand Moon wrote: > Hi Krzysztof, > > On 19 February 2016 at 11:36, Krzysztof Kozlowski > <k.kozlowski@xxxxxxxxxxx> wrote: >> 2016-02-19 2:21 GMT+09:00 Anand Moon <linux.amoon@xxxxxxxxx>: >>> From: Anand Moon <linux.amoon@xxxxxxxxx> >>> >>> pl330_tasklet tasklet uses the same spinlock pch->lock for safe IRQ locking. >>> It's safe to initialize pl330_tasklet tasklet after release of the locking. >> >> This is tasklet init, not tasklet execution (which you are referring >> to in first sentence). I don't get how usage of spinlock during >> execution guarantees the safeness during init... Please describe why >> this is safe. >> >> Best regards, >> Krzysztof >> > > http://lxr.free-electrons.com/source/drivers/dma/pl330.c#L1972 > > pl330_tasklet function which is initiated by tasklet_init is trying to lock > using same spin_unlock_irqsave/restore pch->lock. tasklet_init does not call pl330_tasklet (if this is what you mean by "initiated"). What is the correlation? Why are you referring to the locks in pl330_tasklet? > So better release the pch->lock and then initialize the tasklet_init. Why "better"? Best regards, Krzysztof > >>> >>> Signed-off-by: Anand Moon <linux.amoon@xxxxxxxxx> >>> --- >>> drivers/dma/pl330.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c >>> index 17ee758..df2cab1 100644 >>> --- a/drivers/dma/pl330.c >>> +++ b/drivers/dma/pl330.c >>> @@ -2091,10 +2091,10 @@ static int pl330_alloc_chan_resources(struct dma_chan *chan) >>> return -ENOMEM; >>> } >>> >>> - tasklet_init(&pch->task, pl330_tasklet, (unsigned long) pch); >>> - >>> spin_unlock_irqrestore(&pch->lock, flags); >>> >>> + tasklet_init(&pch->task, pl330_tasklet, (unsigned long) pch); >>> + >>> return 1; >>> } >>> >>> -- >>> 1.9.1 >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe dmaengine" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
