On Wed, Jan 12, 2022 at 4:28 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>
> Hi Zong,
>
> On Tue, Jan 11, 2022 at 9:51 AM Zong Li <zong.li@xxxxxxxxxx> wrote:
> > It currently assumes that there are always four channels, it would
> > cause the error if there is actually less than four channels. Change
> > that by getting number of channel from device tree.
> >
> > For backwards-compatible, it uses the default value (i.e. 4) when there
> > is no 'dma-channels' information in dts.
> >
> > Signed-off-by: Zong Li <zong.li@xxxxxxxxxx>
>
> Thanks for your patch!
>
> > --- a/drivers/dma/sf-pdma/sf-pdma.c
> > +++ b/drivers/dma/sf-pdma/sf-pdma.c
> > @@ -484,21 +484,24 @@ static int sf_pdma_probe(struct platform_device *pdev)
> > struct sf_pdma *pdma;
> > struct sf_pdma_chan *chan;
> > struct resource *res;
> > - int len, chans;
> > - int ret;
> > + int len, ret;
> > const enum dma_slave_buswidth widths =
> > DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
> > DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
> > DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
> > DMA_SLAVE_BUSWIDTH_64_BYTES;
> >
> > - chans = PDMA_NR_CH;
> > - len = sizeof(*pdma) + sizeof(*chan) * chans;
> > + len = sizeof(*pdma) + sizeof(*chan) * PDMA_MAX_NR_CH;
>
> Why is the last part added (yes, this is a pre-existing issue)?
> struct sf_pdma already contains space for chans[PDMA_MAX_NR_CH].
> Either drop the last part, or change sf_pdma.chans[] to a flexible
> array member.
>
> BTW, you can use the struct_size() or flex_array_size() helper
> to calculate len.
Thanks for your suggestions, let me fix it in the next version.
>
> > pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
> > if (!pdma)
> > return -ENOMEM;
> >
> > - pdma->n_chans = chans;
> > + ret = of_property_read_u32(pdev->dev.of_node, "dma-channels",
> > + &pdma->n_chans);
> > + if (ret) {
> > + dev_notice(&pdev->dev, "set number of channels to default value: 4\n");
> > + pdma->n_chans = PDMA_MAX_NR_CH;
> > + }
> >
> > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > pdma->membase = devm_ioremap_resource(&pdev->dev, res);
> > @@ -556,7 +559,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
> > struct sf_pdma_chan *ch;
> > int i;
> >
> > - for (i = 0; i < PDMA_NR_CH; i++) {
> > + for (i = 0; i < pdma->n_chans; i++) {
> > ch = &pdma->chans[i];
>
> If dma-channels in DT > PDMA_NR_CH, this becomes an out-of-bound
> access.
>
Okay, let me get the min() between pdma->chans and PDMA_MAX_NR_CH,
please let me know if it isn't good to you.
> >
> > devm_free_irq(&pdev->dev, ch->txirq, ch);
> > diff --git a/drivers/dma/sf-pdma/sf-pdma.h b/drivers/dma/sf-pdma/sf-pdma.h
> > index 0c20167b097d..8127d792f639 100644
> > --- a/drivers/dma/sf-pdma/sf-pdma.h
> > +++ b/drivers/dma/sf-pdma/sf-pdma.h
> > @@ -22,11 +22,7 @@
> > #include "../dmaengine.h"
> > #include "../virt-dma.h"
> >
> > -#define PDMA_NR_CH 4
> > -
> > -#if (PDMA_NR_CH != 4)
> > -#error "Please define PDMA_NR_CH to 4"
> > -#endif
> > +#define PDMA_MAX_NR_CH 4
> >
> > #define PDMA_BASE_ADDR 0x3000000
> > #define PDMA_CHAN_OFFSET 0x1000
> > @@ -118,7 +114,7 @@ struct sf_pdma {
> > void __iomem *membase;
> > void __iomem *mappedbase;
> > u32 n_chans;
> > - struct sf_pdma_chan chans[PDMA_NR_CH];
> > + struct sf_pdma_chan chans[PDMA_MAX_NR_CH];
> > };
> >
> > #endif /* _SF_PDMA_H */
> -
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
