linux-kernel - Re: [PATCH] net: mscc: ocelot: replace readx_poll_timeout with readx_poll_timeout

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Date:   Fri, 15 May 2020 19:30:04 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Xulin Sun <xulin.sun@...driver.com>
Cc:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>, xulinsun@...il.com
Subject: Re: [PATCH] net: mscc: ocelot: replace readx_poll_timeout with readx_poll_timeout_atomic

Hi Xulin,

On Fri, 15 May 2020 at 06:23, Xulin Sun <xulin.sun@...driver.com> wrote:
>
> This fixes call trace like below to use atomic safe API:
>
> BUG: sleeping function called from invalid context at drivers/net/ethernet/mscc/ocelot.c:59
> in_atomic(): 1, irqs_disabled(): 0, pid: 3778, name: ifconfig
> INFO: lockdep is turned off.
> Preemption disabled at:
> [<ffff2b163c83b78c>] dev_set_rx_mode+0x24/0x40
> Hardware name: LS1028A RDB Board (DT)
> Call trace:
> dump_backtrace+0x0/0x140
> show_stack+0x24/0x30
> dump_stack+0xc4/0x10c
> ___might_sleep+0x194/0x230
> __might_sleep+0x58/0x90
> ocelot_mact_forget+0x74/0xf8
> ocelot_mc_unsync+0x2c/0x38
> __hw_addr_sync_dev+0x6c/0x130
> ocelot_set_rx_mode+0x8c/0xa0
> __dev_set_rx_mode+0x58/0xa0
> dev_set_rx_mode+0x2c/0x40
> __dev_open+0x120/0x190
> __dev_change_flags+0x168/0x1c0
> dev_change_flags+0x3c/0x78
> devinet_ioctl+0x6c4/0x7c8
> inet_ioctl+0x2b8/0x2f8
> sock_do_ioctl+0x54/0x260
> sock_ioctl+0x21c/0x4d0
> do_vfs_ioctl+0x6d4/0x968
> ksys_ioctl+0x84/0xb8
> __arm64_sys_ioctl+0x28/0x38
> el0_svc_common.constprop.0+0x78/0x190
> el0_svc_handler+0x70/0x90
> el0_svc+0x8/0xc
>
> Signed-off-by: Xulin Sun <xulin.sun@...driver.com>
> ---

The code path which you presented in your stack trace is impossible
using code available currently in mainline.

>  drivers/net/ethernet/mscc/ocelot.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
> index b4731df186f4..6c82ab1b3fa6 100644
> --- a/drivers/net/ethernet/mscc/ocelot.c
> +++ b/drivers/net/ethernet/mscc/ocelot.c
> @@ -56,7 +56,7 @@ static inline int ocelot_mact_wait_for_completion(struct ocelot *ocelot)
>  {
>         u32 val;
>
> -       return readx_poll_timeout(ocelot_mact_read_macaccess,
> +       return readx_poll_timeout_atomic(ocelot_mact_read_macaccess,
>                 ocelot, val,
>                 (val & ANA_TABLES_MACACCESS_MAC_TABLE_CMD_M) ==
>                 MACACCESS_CMD_IDLE,
> --
> 2.17.1
>

Regards,
-Vladimir