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From: Can Guo <cang@codeaurora.org>
To: Stanley Chu <stanley.chu@mediatek.com>
Cc: 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, 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>,
	Bean Huo <beanhuo@micron.com>,
	Bart Van Assche <bvanassche@acm.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] scsi: ufs: Fix a possible NULL pointer issue
Date: Tue, 12 Jan 2021 14:52:13 +0800	[thread overview]
Message-ID: <6d03cdacda2f757ba0d0f39ce625eaec@codeaurora.org> (raw)
In-Reply-To: <1610433327.17820.5.camel@mtkswgap22>

On 2021-01-12 14:35, Stanley Chu wrote:
> Hi Can,
> 
> On Sat, 2021-01-02 at 05:59 -0800, 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>
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index e221add..9829c8d 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -94,6 +94,8 @@
>>  		       16, 4, buf, __len, false);                        \
>>  } while (0)
>> 
>> +static bool early_suspend;
>> +
>>  int ufshcd_dump_regs(struct ufs_hba *hba, size_t offset, size_t len,
>>  		     const char *prefix)
>>  {
>> @@ -8896,8 +8898,14 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
>>  	int ret = 0;
>>  	ktime_t start = ktime_get();
>> 
>> +	if (!hba) {
>> +		early_suspend = true;
>> +		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) ==
>> @@ -8945,9 +8953,12 @@ 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 (unlikely(early_suspend)) {
>> +		early_suspend = false;
>> +		down(&hba->eh_sem);
>>  	}
> 
> I guess early_suspend here is to handle the case that hba is null 
> during
> ufshcd_system_suspend() but !null during ufshcd_system_resume(). If 
> yes,
> would it be possible? If no, may I know what is the purpose?
> 

Yes, you are right. I think it is possible. platform_set_drvdata()
is called in ufshcd_pltfrm_init(). Say suspend happens before
platform_set_drvdata() is called, but resume comes back after
platform_set_drvdata() is called. What do you think?

Thanks,
Can Guo.

> Thanks a lot.
> Stanley Chu
> 
>> 
>>  	if (!hba->is_powered || pm_runtime_suspended(hba->dev))

  reply	other threads:[~2021-01-12  6:53 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1609595975-12219-1-git-send-email-cang@codeaurora.org>
2021-01-02 13:59 ` [PATCH 1/2] scsi: ufs: Fix a possible NULL pointer issue Can Guo
2021-01-12  6:35   ` Stanley Chu
2021-01-12  6:52     ` Can Guo [this message]
2021-01-12  9:17       ` Stanley Chu
2021-01-02 13:59 ` [PATCH 2/2] scsi: ufs: Protect PM ops and err_handler from user access through sysfs Can Guo
2021-01-04 20:05   ` Bean Huo
2021-01-05  1:07     ` Can Guo
2021-01-05 18:38       ` Bean Huo
2021-01-06  1:20         ` Can Guo
2021-01-08 11:29           ` Bean Huo
2021-01-08 13:11             ` Stanley Chu
2021-01-09  4:45             ` Can Guo
2021-01-09  4:51               ` Can Guo
2021-01-10 16:13                 ` Bean Huo
2021-01-11  1:27                   ` Can Guo
2021-01-11  8:23                     ` Bean Huo
2021-01-11  9:22                       ` Can Guo
2021-01-11 10:04                         ` Bean Huo
2021-01-12  0:45                           ` Can Guo
2021-01-12 11:32                             ` Bean Huo
2021-01-11  1:52                   ` Can Guo
2021-01-10 16:18   ` Bean Huo
2021-01-11  1:30     ` Can Guo
2021-01-11  8:25       ` Bean Huo
2021-01-12  8:20     ` Avri Altman
2021-01-12  9:36   ` Stanley Chu
     [not found] <1609388736-22525-1-git-send-email-cang@codeaurora.org>
2020-12-31  4:25 ` [PATCH 1/2] scsi: ufs: Fix a possible NULL pointer issue Can Guo

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