It was <2020-08-19 śro 14:48>, when Krzysztof Kozlowski wrote: > On Wed, Aug 19, 2020 at 02:32:06PM +0200, Łukasz Stelmach wrote: >> Signed-off-by: Łukasz Stelmach <l.stelmach@xxxxxxxxxxx> >> --- >> drivers/spi/spi-s3c64xx.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) > > Oh, come on, stop fixing the same local issue without fixing bigger > picture... or at least documenting why bigger picture does not have to be > fixed and simple 'return' is enough. > > That's the third, same fix for the same problem. > > https://lore.kernel.org/lkml/20190314064202.14864-1-kjlu@xxxxxxx/ > https://lore.kernel.org/lkml/20170207204520.h2eo3yn5kge56lk7@kozik-lap/ No wonder. There is a possible NULL dereference below. Now at least we know something about conditions that led to this. Should I drop the entire patch, or just the dmaengine_prep_slave_sg() part? >> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c >> index 505789f91fdf..27d77600a820 100644 >> --- a/drivers/spi/spi-s3c64xx.c >> +++ b/drivers/spi/spi-s3c64xx.c >> @@ -273,6 +273,7 @@ static void prepare_dma(struct s3c64xx_spi_dma_data *dma, >> struct s3c64xx_spi_driver_data *sdd; >> struct dma_slave_config config; >> struct dma_async_tx_descriptor *desc; >> + int ret; >> >> memset(&config, 0, sizeof(config)); >> >> @@ -296,11 +297,22 @@ static void prepare_dma(struct s3c64xx_spi_dma_data *dma, >> >> desc = dmaengine_prep_slave_sg(dma->ch, sgt->sgl, sgt->nents, >> dma->direction, DMA_PREP_INTERRUPT); >> + if (!desc) { >> + dev_err(&sdd->pdev->dev, "unable to prepare %s scatterlist", >> + dma->direction == DMA_DEV_TO_MEM ? "rx" : "tx"); >> + return; >> + } >> >> desc->callback = s3c64xx_spi_dmacb; >> desc->callback_param = dma; >> >> dma->cookie = dmaengine_submit(desc); >> + ret = dma_submit_error(dma->cookie); >> + if (ret) { >> + dev_err(&sdd->pdev->dev, "dmaengine_submit() failed %d", ret); >> + return; >> + } >> + >> dma_async_issue_pending(dma->ch); >> } >> >> -- >> 2.26.2 >> > > -- Łukasz Stelmach Samsung R&D Institute Poland Samsung Electronics
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