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From:   =?ISO-8859-1?Q?J=E9r=F4me?= Pouiller <jerome.pouiller@silabs.com>
To:     Kalle Valo <kvalo@kernel.org>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH v2] wfx: avoid flush_workqueue(system_highpri_wq) usage
Date:   Mon, 02 May 2022 10:38:43 +0200
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Organization: Silicon Labs
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References: <20220225112405.355599-1-Jerome.Pouiller@silabs.com> <87a6c0cuxf.fsf@kernel.org> <f15574a6-aba4-72bc-73af-26fdcdf9fb63@I-love.SAKURA.ne.jp>
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On Monday 2 May 2022 10:16:06 CEST Tetsuo Handa wrote:
> CAUTION: This email originated from outside of the organization. Do not c=
lick links or open attachments unless you recognize the sender and know the=
 content is safe.
>=20
>=20
> Flushing system-wide workqueues is dangerous and will be forbidden.
> Replace system_highpri_wq with per "struct wfx_dev" bh_wq.
>=20
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
> Note: This patch is only compile tested.
>=20
> Changes in v2:
>   Use per "struct wfx_dev" workqueue.
>=20
>  drivers/net/wireless/silabs/wfx/bh.c     | 6 +++---
>  drivers/net/wireless/silabs/wfx/hif_tx.c | 2 +-
>  drivers/net/wireless/silabs/wfx/main.c   | 6 ++++++
>  drivers/net/wireless/silabs/wfx/wfx.h    | 1 +
>  4 files changed, 11 insertions(+), 4 deletions(-)
>=20
> diff --git a/drivers/net/wireless/silabs/wfx/bh.c b/drivers/net/wireless/=
silabs/wfx/bh.c
> index bcea9d5b119c..21dfdcf9cc27 100644
> --- a/drivers/net/wireless/silabs/wfx/bh.c
> +++ b/drivers/net/wireless/silabs/wfx/bh.c
> @@ -267,7 +267,7 @@ void wfx_bh_request_rx(struct wfx_dev *wdev)
>         wfx_control_reg_read(wdev, &cur);
>         prev =3D atomic_xchg(&wdev->hif.ctrl_reg, cur);
>         complete(&wdev->hif.ctrl_ready);
> -       queue_work(system_highpri_wq, &wdev->hif.bh);
> +       queue_work(wdev->bh_wq, &wdev->hif.bh);
>=20
>         if (!(cur & CTRL_NEXT_LEN_MASK))
>                 dev_err(wdev->dev, "unexpected control register value: le=
ngth field is 0: %04x\n",
> @@ -280,7 +280,7 @@ void wfx_bh_request_rx(struct wfx_dev *wdev)
>  /* Driver want to send data */
>  void wfx_bh_request_tx(struct wfx_dev *wdev)
>  {
> -       queue_work(system_highpri_wq, &wdev->hif.bh);
> +       queue_work(wdev->bh_wq, &wdev->hif.bh);
>  }
>=20
>  /* If IRQ is not available, this function allow to manually poll the con=
trol register and simulate
> @@ -295,7 +295,7 @@ void wfx_bh_poll_irq(struct wfx_dev *wdev)
>         u32 reg;
>=20
>         WARN(!wdev->poll_irq, "unexpected IRQ polling can mask IRQ");
> -       flush_workqueue(system_highpri_wq);
> +       flush_workqueue(wdev->bh_wq);
>         start =3D ktime_get();
>         for (;;) {
>                 wfx_control_reg_read(wdev, &reg);
> diff --git a/drivers/net/wireless/silabs/wfx/hif_tx.c b/drivers/net/wirel=
ess/silabs/wfx/hif_tx.c
> index 9c653d0e9034..d35dd940d968 100644
> --- a/drivers/net/wireless/silabs/wfx/hif_tx.c
> +++ b/drivers/net/wireless/silabs/wfx/hif_tx.c
> @@ -73,7 +73,7 @@ int wfx_cmd_send(struct wfx_dev *wdev, struct wfx_hif_m=
sg *request,
>=20
>         if (no_reply) {
>                 /* Chip won't reply. Ensure the wq has send the buffer be=
fore to continue. */
> -               flush_workqueue(system_highpri_wq);
> +               flush_workqueue(wdev->bh_wq);
>                 ret =3D 0;
>                 goto end;
>         }
> diff --git a/drivers/net/wireless/silabs/wfx/main.c b/drivers/net/wireles=
s/silabs/wfx/main.c
> index e575a81ca2ca..e015bfb8d221 100644
> --- a/drivers/net/wireless/silabs/wfx/main.c
> +++ b/drivers/net/wireless/silabs/wfx/main.c
> @@ -345,6 +345,10 @@ int wfx_probe(struct wfx_dev *wdev)
>         wdev->pdata.gpio_wakeup =3D NULL;
>         wdev->poll_irq =3D true;
>=20
> +       wdev->bh_wq =3D alloc_workqueue("wfx_bh_wq", WQ_HIGHPRI, 0);
> +       if (!wdev->bh_wq)
> +               return -ENOMEM;
> +
>         wfx_bh_register(wdev);
>=20
>         err =3D wfx_init_device(wdev);
> @@ -458,6 +462,7 @@ int wfx_probe(struct wfx_dev *wdev)
>         wdev->hwbus_ops->irq_unsubscribe(wdev->hwbus_priv);
>  bh_unregister:
>         wfx_bh_unregister(wdev);
> +       destroy_workqueue(wdev->bh_wq);
>         return err;
>  }
>=20
> @@ -467,6 +472,7 @@ void wfx_release(struct wfx_dev *wdev)
>         wfx_hif_shutdown(wdev);
>         wdev->hwbus_ops->irq_unsubscribe(wdev->hwbus_priv);
>         wfx_bh_unregister(wdev);
> +       destroy_workqueue(wdev->bh_wq);
>  }
>=20
>  static int __init wfx_core_init(void)
> diff --git a/drivers/net/wireless/silabs/wfx/wfx.h b/drivers/net/wireless=
/silabs/wfx/wfx.h
> index 6594cc647c2f..6f5e95dae21f 100644
> --- a/drivers/net/wireless/silabs/wfx/wfx.h
> +++ b/drivers/net/wireless/silabs/wfx/wfx.h
> @@ -57,6 +57,7 @@ struct wfx_dev {
>         struct mutex               rx_stats_lock;
>         struct wfx_hif_tx_power_loop_info tx_power_loop_info;
>         struct mutex               tx_power_loop_info_lock;
> +       struct workqueue_struct    *bh_wq;
>  };
>=20
>  struct wfx_vif {
> --
> 2.34.1
>=20
>=20
>=20

It's right for me.

Signed-off-by: J=E9r=F4me Pouiller <jerome.pouiller@silabs.com>

--=20
J=E9r=F4me Pouiller