Re: [PATCH v7 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling while atomic

Can Guo
2020-02-10T01:28:48Z

On 2020-02-06 18:28, Avri Altman wrote:
> Hi,
>
>>
>> The async version of ufshcd_hold(async == true), which is only called
>> in queuecommand path as for now, is expected to work in atomic
>> context,
>> thus it should not sleep or schedule out. When it runs into the
>> condition
>> that clocks are ON but link is still in hibern8 state, it should bail
>> out
>> without flushing the clock ungate work.
>
> Fixes: f2a785ac2312 (scsi: ufshcd: Fix race between clk scaling and
> ungate work)

Sorry, missed this one, if another version is needed, I will add this
line.

>>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
>> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
>> Reviewed-by: Bean Huo <beanhuo@micron.com>
>> Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
>> ---
>> drivers/scsi/ufs/ufshcd.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index bbc2607..e8f7f9d 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -1518,6 +1518,11 @@ int ufshcd_hold(struct ufs_hba *hba, bool
>> async)
>> */
>> if (ufshcd_can_hibern8_during_gating(hba) &&
>> ufshcd_is_link_hibern8(hba)) {
>> + if (async) {
>> + rc = -EAGAIN;
>> + hba->clk_gating.active_reqs--;
>> + break;
>> + }
>> spin_unlock_irqrestore(hba->host->host_lock,
>> flags);
>> flush_work(&hba->clk_gating.ungate_work);
>> spin_lock_irqsave(hba->host->host_lock,
>> flags);
> Since now the above code is shared in all cases,
> Maybe find a more economical way to pack it?
>
> Thanks,
> Avri
>
>

There are only 2 of this same code pieces in ufshcd_hold() and located
in different cases, meanwhile there can be fall through, I don't see
a good way to pack it, can you suggest if you have any ideas?

Regards,
Can Guo.

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