linux-kernel - RE: [PATCH] scsi: ufs-qcom: Fix scheduling while atomic issue

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Date:   Tue, 26 May 2020 06:25:47 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Jeffrey Hugo <jeffrey.l.hugo@...il.com>,
        "agross@...nel.org" <agross@...nel.org>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "subhashj@...eaurora.org" <subhashj@...eaurora.org>,
        "venkatg@...eaurora.org" <venkatg@...eaurora.org>
CC:     "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] scsi: ufs-qcom: Fix scheduling while atomic issue

 
> ufs_qcom_dump_dbg_regs() uses usleep_range, a sleeping function, but can
> be called from atomic context in the following flow:
> 
> ufshcd_intr -> ufshcd_sl_intr -> ufshcd_check_errors ->
> ufshcd_print_host_regs -> ufshcd_vops_dbg_register_dump ->
> ufs_qcom_dump_dbg_regs
> 
> This causes a boot crash on the Lenovo Miix 630 when the interrupt is
> handled on the idle thread.
> 
> Fix the issue by switching to udelay().
> 
> Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers")
> Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@...il.com>
Reviewed-by: Avri Altman <avri.altman@....com>