2020-12-14 15:25:50

by Bean Huo

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

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 <[email protected]>
> ---
> 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;"?

2020-12-18 05:47:49

by Can Guo

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

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 <[email protected]>
>> ---
>> 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.