Hi Marek,
On Mon, Apr 3, 2017 at 12:21 AM, Marek Szyprowski
<m.szyprowski@xxxxxxxxxxx> wrote:
> This patch adds missing checks for dma_map_single() failure and proper error
> reporting. Although this issue was harmless on ARM architecture, it is always
> good to use the DMA mapping API in a proper way. This patch fixes the following
> DMA API debug warning:
>
> WARNING: CPU: 1 PID: 3785 at lib/dma-debug.c:1171 check_unmap+0x8a0/0xf28
> dma-pl330 121a0000.pdma: DMA-API: device driver failed to check map error[device address=0x000000006e0f9000] [size=4096 bytes] [mapped as single]
> Modules linked in:
> CPU: 1 PID: 3785 Comm: (agetty) Tainted: G W 4.11.0-rc1-00137-g07ca963-dirty #59
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> [<c011aaa4>] (unwind_backtrace) from [<c01127c0>] (show_stack+0x20/0x24)
> [<c01127c0>] (show_stack) from [<c06ba5d8>] (dump_stack+0x84/0xa0)
> [<c06ba5d8>] (dump_stack) from [<c0139528>] (__warn+0x14c/0x180)
> [<c0139528>] (__warn) from [<c01395a4>] (warn_slowpath_fmt+0x48/0x50)
> [<c01395a4>] (warn_slowpath_fmt) from [<c072a114>] (check_unmap+0x8a0/0xf28)
> [<c072a114>] (check_unmap) from [<c072a834>] (debug_dma_unmap_page+0x98/0xc8)
> [<c072a834>] (debug_dma_unmap_page) from [<c0803874>] (s3c24xx_serial_shutdown+0x314/0x52c)
> [<c0803874>] (s3c24xx_serial_shutdown) from [<c07f5124>] (uart_port_shutdown+0x54/0x88)
> [<c07f5124>] (uart_port_shutdown) from [<c07f522c>] (uart_shutdown+0xd4/0x110)
> [<c07f522c>] (uart_shutdown) from [<c07f6a8c>] (uart_hangup+0x9c/0x208)
> [<c07f6a8c>] (uart_hangup) from [<c07c426c>] (__tty_hangup+0x49c/0x634)
> [<c07c426c>] (__tty_hangup) from [<c07c78ac>] (tty_ioctl+0xc88/0x16e4)
> [<c07c78ac>] (tty_ioctl) from [<c03b5f2c>] (do_vfs_ioctl+0xc4/0xd10)
> [<c03b5f2c>] (do_vfs_ioctl) from [<c03b6bf4>] (SyS_ioctl+0x7c/0x8c)
> [<c03b6bf4>] (SyS_ioctl) from [<c010b4a0>] (ret_fast_syscall+0x0/0x3c)
>
> Reported-by: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx>
> Fixes: 62c37eedb74c8 ("serial: samsung: add dma reqest/release functions")
> CC: stable@xxxxxxxxxxxxxxx # v4.10+
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
> ---
Looks good.
Reviewed-by: shuahkh@xxxxxxxxxxxxxxx
thanks,
-- Shuah
> This issue was there since adding DMA support, but this patch applies cleanly
> only to v4.10+ kernels due to other changes in the surrounding code.
>
> v3:
> - moved spinlock removal to separate patch, extended commit message
>
> v2:
> - fixed commit id in 'fixes' tag, added 'reviewed-by' tag
> ---
> drivers/tty/serial/samsung.c | 31 ++++++++++++++++++++++++-------
> 1 file changed, 24 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
> index 9f3759bdb44f..ca0bcd7fd61f 100644
> --- a/drivers/tty/serial/samsung.c
> +++ b/drivers/tty/serial/samsung.c
> @@ -859,7 +859,7 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
> static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
> {
> struct s3c24xx_uart_dma *dma = p->dma;
> - unsigned long flags;
> + int ret;
>
> /* Default slave configuration parameters */
> dma->rx_conf.direction = DMA_DEV_TO_MEM;
> @@ -884,8 +884,8 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
>
> dma->tx_chan = dma_request_chan(p->port.dev, "tx");
> if (IS_ERR(dma->tx_chan)) {
> - dma_release_channel(dma->rx_chan);
> - return PTR_ERR(dma->tx_chan);
> + ret = PTR_ERR(dma->tx_chan);
> + goto err_release_rx;
> }
>
> dmaengine_slave_config(dma->tx_chan, &dma->tx_conf);
> @@ -894,15 +894,17 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
> dma->rx_size = PAGE_SIZE;
>
> dma->rx_buf = kmalloc(dma->rx_size, GFP_KERNEL);
> -
> if (!dma->rx_buf) {
> - dma_release_channel(dma->rx_chan);
> - dma_release_channel(dma->tx_chan);
> - return -ENOMEM;
> + ret = -ENOMEM;
> + goto err_release_tx;
> }
>
> dma->rx_addr = dma_map_single(p->port.dev, dma->rx_buf,
> dma->rx_size, DMA_FROM_DEVICE);
> + if (dma_mapping_error(p->port.dev, dma->rx_addr)) {
> + ret = -EIO;
> + goto err_free_rx;
> + }
>
> spin_lock_irqsave(&p->port.lock, flags);
>
> @@ -911,8 +913,23 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
> UART_XMIT_SIZE, DMA_TO_DEVICE);
>
> spin_unlock_irqrestore(&p->port.lock, flags);
> + if (dma_mapping_error(p->port.dev, dma->tx_addr)) {
> + ret = -EIO;
> + goto err_unmap_rx;
> + }
>
> return 0;
> +
> +err_unmap_rx:
> + dma_unmap_single(p->port.dev, dma->rx_addr, dma->rx_size,
> + DMA_FROM_DEVICE);
> +err_free_rx:
> + kfree(dma->rx_buf);
> +err_release_tx:
> + dma_release_channel(dma->tx_chan);
> +err_release_rx:
> + dma_release_channel(dma->rx_chan);
> + return ret;
> }
>
> static void s3c24xx_serial_release_dma(struct s3c24xx_uart_port *p)
> --
> 1.9.1
>