linux-kernel - Re: [PATCH 4.11 097/114] serial: samsung: Add missing checks for dma_map

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Date:   Thu, 18 May 2017 14:18:30 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH 4.11 097/114] serial: samsung: Add missing checks for
 dma_map_single failure

On Thu, May 18, 2017 at 12:46 PM, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> 4.11-stable review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: Marek Szyprowski <m.szyprowski@...sung.com>
>
> commit 500fcc08a32bfd54f11951ba81530775df15c474 upstream.
>
> 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@...sung.com>
> Fixes: 62c37eedb74c8 ("serial: samsung: add dma reqest/release functions")
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Reviewed-by: Shuah Khan <shuahkh@....samsung.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>
> ---
>  drivers/tty/serial/samsung.c |   31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
>
> --- a/drivers/tty/serial/samsung.c
> +++ b/drivers/tty/serial/samsung.c
> @@ -859,7 +859,7 @@ static void s3c24xx_serial_break_ctl(str
>  static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
>  {
>         struct s3c24xx_uart_dma *dma = p->dma;
> -       unsigned long flags;
> +       int ret;

This does not compile:
http://www.krzk.eu/#/builders/5/builds/225
It works fine in mainline because the patch 3/3 of the set was
removing the user of the flags.

I'll send a fixup for stable.

BR,
Krzysztof