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Date:   Fri, 11 Dec 2020 09:11:55 +0800
From:   Can Guo <cang@codeaurora.org>
To:     Bean Huo <huobean@gmail.com>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        hongwus@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>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Satya Tangirala <satyat@google.com>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] scsi: ufs: Clean up ufshcd_exit_clk_scaling/gating()
In-Reply-To: <f12d2c516d2a038bcc27677d9b982c52d19d5027.camel@gmail.com>
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 <f12d2c516d2a038bcc27677d9b982c52d19d5027.camel@gmail.com>
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On 2020-12-11 02:03, Bean Huo wrote:
> On Wed, 2020-12-09 at 05:35 -0800, Can Guo wrote:
>> ufshcd_hba_exit() is always called after ufshcd_exit_clk_scaling()
>> and
>> ufshcd_exit_clk_gating(), so move ufshcd_exit_clk_scaling/gating() to
>> ufshcd_hba_exit().
>> 
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 12266bd..41a12d6 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -1846,11 +1846,14 @@ static void ufshcd_init_clk_scaling(struct
>> ufs_hba *hba)
>>         snprintf(wq_name, sizeof(wq_name), "ufs_clkscaling_%d",
>>                  hba->host->host_no);
>>         hba->clk_scaling.workq =
>> create_singlethread_workqueue(wq_name);
>> +
>> +       hba->clk_scaling.is_initialized = true;
>>  }
>> 
>>  static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
>>  {
>> -       if (!ufshcd_is_clkscaling_supported(hba))
>> +       if (!ufshcd_is_clkscaling_supported(hba) ||
>> +           !hba->clk_scaling.is_initialized)
>>                 return;
>> 
>>         if (hba->devfreq)
>> @@ -1894,12 +1897,16 @@ static void ufshcd_init_clk_gating(struct
>> ufs_hba *hba)
>>         hba->clk_gating.enable_attr.attr.mode = 0644;
>>         if (device_create_file(hba->dev, &hba-
>> >clk_gating.enable_attr))
>>                 dev_err(hba->dev, "Failed to create sysfs for
>> clkgate_enable\n");
>> +
>> +       hba->clk_gating.is_initialized = true;
>>  }
> 
> you don't need these two is_initialized at all. they are only be false
> when scaling/gating is not supported??
> 
> Bean

In the case of scaling/gating are supported, the flags are used in
ufshcd_exit_clk_scaling/gating() - when ufshcd_hba_exit() calls
ufshcd_exit_clk_scaling/gating(), the two funcs need to make sure
they really have something to remove, otherwise NULL pointer issues.

Can Guo.