[PATCH V2 1/1] scsi: ufs: Fix a possible NULL pointer issue

[PATCH V2 1/1] scsi: ufs: Fix a possible NULL pointer issue

[Can Guo]

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 c1c401b..ef155a9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -8883,8 +8883,11 @@ 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) ==
@@ -8932,10 +8935,8 @@ 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))
 		/*
-- 
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Re: [PATCH V2 1/1] scsi: ufs: Fix a possible NULL pointer issue

[Bean Huo]

On Sun, 2020-12-13 at 19:41 -0800, Can Guo wrote:
> 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 c1c401b..ef155a9 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -8883,8 +8883,11 @@ 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;


Can,

why not moving down(&hba->eh_sem) after "return 0;"?

Re: [PATCH V2 1/1] scsi: ufs: Fix a possible NULL pointer issue

[Can Guo]

On 2020-12-14 22:32, Bean Huo wrote:
> On Sun, 2020-12-13 at 19:41 -0800, Can Guo wrote:
>> 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 c1c401b..ef155a9 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -8883,8 +8883,11 @@ 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;
> 
> 
> Can,
> 
> why not moving down(&hba->eh_sem) after "return 0;"?

In your way, if hba is not powered, ufshcd_system_suspend() returns
0, which is a successful suspend. When ufshcd_system_resume() is called,
if hba is not powered, it goes to out and does up(&hba->eh_sem), which
shall cause unbalance to eh_sem.

Thanks,

Can Guo.