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From:   Avri Altman <Avri.Altman@wdc.com>
To:     Can Guo <cang@codeaurora.org>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
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CC:     Alim Akhtar <alim.akhtar@samsung.com>,
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Subject: RE: [PATCH v7 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling
 while atomic
Thread-Topic: [PATCH v7 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling
 while atomic
Thread-Index: AQHV3Mg4iYpOiwL+2EGQ9TyFrLdqL6gN6BAQ
Date:   Thu, 6 Feb 2020 10:28:16 +0000
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Hi,

>=20
> The async version of ufshcd_hold(async =3D=3D true), which is only called
> in queuecommand path as for now, is expected to work in atomic context,
> thus it should not sleep or schedule out. When it runs into the condition
> that clocks are ON but link is still in hibern8 state, it should bail out
> without flushing the clock ungate work.

Fixes: f2a785ac2312 (scsi: ufshcd: Fix race between clk scaling and ungate =
work)
>=20
> Signed-off-by: Can Guo <cang@codeaurora.org>
> Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
> Reviewed-by: Bean Huo <beanhuo@micron.com>
> Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 5 +++++
>  1 file changed, 5 insertions(+)
>=20
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index bbc2607..e8f7f9d 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1518,6 +1518,11 @@ int ufshcd_hold(struct ufs_hba *hba, bool async)
>                  */
>                 if (ufshcd_can_hibern8_during_gating(hba) &&
>                     ufshcd_is_link_hibern8(hba)) {
> +                       if (async) {
> +                               rc =3D -EAGAIN;
> +                               hba->clk_gating.active_reqs--;
> +                               break;
> +                       }
>                         spin_unlock_irqrestore(hba->host->host_lock, flag=
s);
>                         flush_work(&hba->clk_gating.ungate_work);
>                         spin_lock_irqsave(hba->host->host_lock, flags);
Since now the above code is shared in all cases,
Maybe find a more economical way to pack it?

Thanks,
Avri


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