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Subject: Re: [PATCH v2 1/2] scsi: ufs: Fix a possible NULL pointer issue
To:     Can Guo <cang@codeaurora.org>, asutoshd@codeaurora.org,
        nguyenb@codeaurora.org, hongwus@codeaurora.org,
        ziqichen@codeaurora.org, rnayak@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        saravanak@google.com, salyzyn@google.com
Cc:     Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        open list <linux-kernel@vger.kernel.org>
References: <1609479893-8889-1-git-send-email-cang@codeaurora.org>
 <1609479893-8889-2-git-send-email-cang@codeaurora.org>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <7cff30c3-6df8-7b8c-0f5b-a95980b8f706@acm.org>
Date:   Fri, 1 Jan 2021 08:05:01 -0800
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On 12/31/20 9:44 PM, Can Guo wrote:
> During system resume/suspend, hba could be NULL. In this case, do not touch
> eh_sem.
> 
> Fixes: 88a92d6ae4fe ("scsi: ufs: Serialize eh_work with system PM events and async scan")
> 
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e221add..34e2541 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -8896,8 +8896,11 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
>  	int ret = 0;
>  	ktime_t start = ktime_get();
>  
> +	if (!hba)
> +		return 0;
> +
>  	down(&hba->eh_sem);
> -	if (!hba || !hba->is_powered)
> +	if (!hba->is_powered)
>  		return 0;
>  
>  	if ((ufs_get_pm_lvl_to_dev_pwr_mode(hba->spm_lvl) ==
> @@ -8945,10 +8948,8 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  	int ret = 0;
>  	ktime_t start = ktime_get();
>  
> -	if (!hba) {
> -		up(&hba->eh_sem);
> +	if (!hba)
>  		return -EINVAL;
> -	}
>  
>  	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
>  		/*

Hi Can,

How can ufshcd_system_suspend() or ufshcd_system_resume() be called with a
NULL argument? In ufshcd_pci_probe() I see that pci_set_drvdata() is called
before pm_runtime_allow(). ufshcd_pci_remove() calls pm_runtime_forbid().

Thanks,

Bart.