On Wed, Dec 23 2015 at 12:45:31 AM, Saurabh Sengar <saurabh.truth@xxxxxxxxx> wrote: > On 23 December 2015 at 09:05, Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx> wrote: >> This reverts commit e958e079e254 ("dmaengine: mic_x100: add missing >> spin_unlock"). >> >> The above patch is incorrect. There is nothing wrong with the original >> code. The spin_lock is acquired in the "prep" functions and released >> in "submit". > > Hi Ashutosh, > > If it is need to be released by submit function, we don't require the > spin_unlock on success case as well. > am I correct ? No, you are wrong. In the prep functions, we are not using spin_unlock in success cases but in failure ones. >> Signed-off-by: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx> >> --- >> drivers/dma/mic_x100_dma.c | 15 +++++---------- >> 1 file changed, 5 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/dma/mic_x100_dma.c b/drivers/dma/mic_x100_dma.c >> index cddfa8d..068e920 100644 >> --- a/drivers/dma/mic_x100_dma.c >> +++ b/drivers/dma/mic_x100_dma.c >> @@ -317,7 +317,6 @@ mic_dma_prep_memcpy_lock(struct dma_chan *ch, dma_addr_t dma_dest, >> struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch); >> struct device *dev = mic_dma_ch_to_device(mic_ch); >> int result; >> - struct dma_async_tx_descriptor *tx = NULL; >> >> if (!len && !flags) >> return NULL; >> @@ -325,13 +324,10 @@ mic_dma_prep_memcpy_lock(struct dma_chan *ch, dma_addr_t dma_dest, >> spin_lock(&mic_ch->prep_lock); >> result = mic_dma_do_dma(mic_ch, flags, dma_src, dma_dest, len); >> if (result >= 0) >> - tx = allocate_tx(mic_ch); >> - >> - if (!tx) >> - dev_err(dev, "Error enqueueing dma, error=%d\n", result); >> - >> + return allocate_tx(mic_ch); >> + dev_err(dev, "Error enqueueing dma, error=%d\n", result); >> spin_unlock(&mic_ch->prep_lock); > > This spin_unlock shouldn't be required as explained it is getting > released by submit function This is a failure case. Submit will not be called in this case so spin_unlock needs to be called here. >> - return tx; >> + return NULL; >> } >> >> static struct dma_async_tx_descriptor * >> @@ -339,14 +335,13 @@ mic_dma_prep_interrupt_lock(struct dma_chan *ch, unsigned long flags) >> { >> struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch); >> int ret; >> - struct dma_async_tx_descriptor *tx = NULL; >> >> spin_lock(&mic_ch->prep_lock); >> ret = mic_dma_do_dma(mic_ch, flags, 0, 0, 0); >> if (!ret) >> - tx = allocate_tx(mic_ch); >> + return allocate_tx(mic_ch); >> spin_unlock(&mic_ch->prep_lock); > > and this too ? Yes, this too. >> - return tx; >> + return NULL; >> } >> >> /* Return the status of the transaction */ >> -- >> 2.0.0.rc3.2.g998f840 >> -- 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