On 22/04/16 13:44, Shardar Shariff Md wrote:
> Initialize default channel slave_id(req_sel) to invalid id
> (i.e max supported slave id + 1) to avoid overwriting of slave_id
> during tegra_dma_slave_config() with client data if slave_id
> is not initialized through DT
>
> Signed-off-by: Shardar Shariff Md <smohammed@xxxxxxxxxx>
>
> ---
> - Instead of initializing the slave id to -1 define macros for
> max slave id and invalid slave id and do the checks accordingly.
> ---
> drivers/dma/tegra20-apb-dma.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index 3871f29..2957e26 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -114,6 +114,9 @@
> /* Channel base address offset from APBDMA base address */
> #define TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET 0x1000
>
> +#define TEGRA_APBDMA_SLAVE_ID_MAX 31
> +#define TEGRA_APBDMA_SLAVE_ID_INVALID (TEGRA_APBDMA_SLAVE_ID_MAX + 1)
> +
> struct tegra_dma;
>
> /*
> @@ -353,7 +356,7 @@ static int tegra_dma_slave_config(struct dma_chan *dc,
> }
>
> memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
> - if (!tdc->slave_id)
> + if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID)
> tdc->slave_id = sconfig->slave_id;
> tdc->config_init = true;
> return 0;
> @@ -1236,7 +1239,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
> }
> pm_runtime_put(tdma->dev);
>
> - tdc->slave_id = 0;
> + tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
> }
>
> static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
> @@ -1253,6 +1256,11 @@ static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
> tdc = to_tegra_dma_chan(chan);
> tdc->slave_id = dma_spec->args[0];
>
> + if (tdc->slave_id > TEGRA_APBDMA_SLAVE_ID_MAX) {
> + dev_err(tdc2dev(tdc), "Invalid slave id\n");
> + return NULL;
> + }
Please move this test to before the dma_get_any_slave_channel(),
otherwise we could leak the DMA channel!
Cheers
Jon
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