netdev - RE: [PATCH AUTOSEL 5.13 09/21] qed: fix possible unpaired spin_{un}lock_bh in _qed_mcp_cmd_and

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Message-ID: <AM6PR08MB4376DF5C31C64EBFCB0276ECF7E99@AM6PR08MB4376.eurprd08.prod.outlook.com>
Date:   Tue, 27 Jul 2021 13:30:15 +0000
From:   Justin He <Justin.He@....com>
To:     Sasha Levin <sashal@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Lijian Zhang <Lijian.Zhang@....com>,
        "David S . Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH AUTOSEL 5.13 09/21] qed: fix possible unpaired
 spin_{un}lock_bh in _qed_mcp_cmd_and_union()

Hi, Sasha

> -----Original Message-----
> From: Sasha Levin <sashal@...nel.org>
> Sent: Tuesday, July 27, 2021 9:19 PM
> To: linux-kernel@...r.kernel.org; stable@...r.kernel.org
> Cc: Justin He <Justin.He@....com>; Lijian Zhang <Lijian.Zhang@....com>;
> David S . Miller <davem@...emloft.net>; Sasha Levin <sashal@...nel.org>;
> netdev@...r.kernel.org
> Subject: [PATCH AUTOSEL 5.13 09/21] qed: fix possible unpaired
> spin_{un}lock_bh in _qed_mcp_cmd_and_union()
>
> From: Jia He <justin.he@....com>
If possible, please stop taking this commit to any stable version because
it has been reverted by later commit.

This patch is harmless but pointless.

Sorry for the inconvenience.

--
Cheers,
Justin (Jia He)


>
> [ Upstream commit 6206b7981a36476f4695d661ae139f7db36a802d ]
>
> Liajian reported a bug_on hit on a ThunderX2 arm64 server with FastLinQ
> QL41000 ethernet controller:
>  BUG: scheduling while atomic: kworker/0:4/531/0x00000200
>   [qed_probe:488()]hw prepare failed
>   kernel BUG at mm/vmalloc.c:2355!
>   Internal error: Oops - BUG: 0 [#1] SMP
>   CPU: 0 PID: 531 Comm: kworker/0:4 Tainted: G W 5.4.0-77-generic #86-
> Ubuntu
>   pstate: 00400009 (nzcv daif +PAN -UAO)
>  Call trace:
>   vunmap+0x4c/0x50
>   iounmap+0x48/0x58
>   qed_free_pci+0x60/0x80 [qed]
>   qed_probe+0x35c/0x688 [qed]
>   __qede_probe+0x88/0x5c8 [qede]
>   qede_probe+0x60/0xe0 [qede]
>   local_pci_probe+0x48/0xa0
>   work_for_cpu_fn+0x24/0x38
>   process_one_work+0x1d0/0x468
>   worker_thread+0x238/0x4e0
>   kthread+0xf0/0x118
>   ret_from_fork+0x10/0x18
>
> In this case, qed_hw_prepare() returns error due to hw/fw error, but in
> theory work queue should be in process context instead of interrupt.
>
> The root cause might be the unpaired spin_{un}lock_bh() in
> _qed_mcp_cmd_and_union(), which causes botton half is disabled incorrectly.
>
> Reported-by: Lijian Zhang <Lijian.Zhang@....com>
> Signed-off-by: Jia He <justin.he@....com>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/net/ethernet/qlogic/qed/qed_mcp.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/qlogic/qed/qed_mcp.c
> b/drivers/net/ethernet/qlogic/qed/qed_mcp.c
> index cd882c453394..caeef25c89bb 100644
> --- a/drivers/net/ethernet/qlogic/qed/qed_mcp.c
> +++ b/drivers/net/ethernet/qlogic/qed/qed_mcp.c
> @@ -474,14 +474,18 @@ _qed_mcp_cmd_and_union(struct qed_hwfn *p_hwfn,
>
>               spin_lock_bh(&p_hwfn->mcp_info->cmd_lock);
>
> -             if (!qed_mcp_has_pending_cmd(p_hwfn))
> +             if (!qed_mcp_has_pending_cmd(p_hwfn)) {
> +                     spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>                       break;
> +             }
>
>               rc = qed_mcp_update_pending_cmd(p_hwfn, p_ptt);
> -             if (!rc)
> +             if (!rc) {
> +                     spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>                       break;
> -             else if (rc != -EAGAIN)
> +             } else if (rc != -EAGAIN) {
>                       goto err;
> +             }
>
>               spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>
> @@ -498,6 +502,8 @@ _qed_mcp_cmd_and_union(struct qed_hwfn *p_hwfn,
>               return -EAGAIN;
>       }
>
> +     spin_lock_bh(&p_hwfn->mcp_info->cmd_lock);
> +
>       /* Send the mailbox command */
>       qed_mcp_reread_offsets(p_hwfn, p_ptt);
>       seq_num = ++p_hwfn->mcp_info->drv_mb_seq;
> @@ -524,14 +530,18 @@ _qed_mcp_cmd_and_union(struct qed_hwfn *p_hwfn,
>
>               spin_lock_bh(&p_hwfn->mcp_info->cmd_lock);
>
> -             if (p_cmd_elem->b_is_completed)
> +             if (p_cmd_elem->b_is_completed) {
> +                     spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>                       break;
> +             }
>
>               rc = qed_mcp_update_pending_cmd(p_hwfn, p_ptt);
> -             if (!rc)
> +             if (!rc) {
> +                     spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>                       break;
> -             else if (rc != -EAGAIN)
> +             } else if (rc != -EAGAIN) {
>                       goto err;
> +             }
>
>               spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>       } while (++cnt < max_retries);
> @@ -554,6 +564,7 @@ _qed_mcp_cmd_and_union(struct qed_hwfn *p_hwfn,
>               return -EAGAIN;
>       }
>
> +     spin_lock_bh(&p_hwfn->mcp_info->cmd_lock);
>       qed_mcp_cmd_del_elem(p_hwfn, p_cmd_elem);
>       spin_unlock_bh(&p_hwfn->mcp_info->cmd_lock);
>
> --
> 2.30.2

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