Messages in this thread | | | Date | Tue, 03 Nov 2020 13:28:10 +0800 | From | Can Guo <> | Subject | Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable |
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On 2020-10-29 03:43, Jaegeuk Kim wrote: > On 10/27, Can Guo wrote: >> On 2020-10-27 11:33, Jaegeuk Kim wrote: >> > On 10/27, Can Guo wrote: >> > > On 2020-10-27 03:51, Jaegeuk Kim wrote: >> > > > From: Jaegeuk Kim <jaegeuk@google.com> >> > > > >> > > > When giving a stress test which enables/disables clkgating, we hit >> > > > device >> > > > timeout sometimes. This patch avoids subtle racy condition to address >> > > > it. >> > > > >> > > > Note that, this requires a patch to address the device stuck by >> > > > REQ_CLKS_OFF in >> > > > __ufshcd_release(). >> > > > >> > > > The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF". >> > > >> > > Why don't you just squash the fix into this one? >> > >> > I'm seeing this patch just revealed that problem. >> >> That scenario (back to back calling of ufshcd_release()) only happens >> when you stress the clkgate_enable sysfs node, so let's keep the fix >> as one to make things simple. What do you think? > > If we don't have this patch, do you think this issue won't happen at > all? >
At least I've never seen this scenario these years, otherwise I would have put up a fix.
Thanks,
Can Guo.
>> >> Thanks, >> >> Can Guo. >> >> > >> > > >> > > Thanks, >> > > >> > > Can Guo. >> > > >> > > > >> > > > Signed-off-by: Jaegeuk Kim <jaegeuk@google.com> >> > > > --- >> > > > drivers/scsi/ufs/ufshcd.c | 12 ++++++------ >> > > > 1 file changed, 6 insertions(+), 6 deletions(-) >> > > > >> > > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c >> > > > index cc8d5f0c3fdc..6c9269bffcbd 100644 >> > > > --- a/drivers/scsi/ufs/ufshcd.c >> > > > +++ b/drivers/scsi/ufs/ufshcd.c >> > > > @@ -1808,19 +1808,19 @@ static ssize_t >> > > > ufshcd_clkgate_enable_store(struct device *dev, >> > > > return -EINVAL; >> > > > >> > > > value = !!value; >> > > > + >> > > > + spin_lock_irqsave(hba->host->host_lock, flags); >> > > > if (value == hba->clk_gating.is_enabled) >> > > > goto out; >> > > > >> > > > - if (value) { >> > > > - ufshcd_release(hba); >> > > > - } else { >> > > > - spin_lock_irqsave(hba->host->host_lock, flags); >> > > > + if (value) >> > > > + __ufshcd_release(hba); >> > > > + else >> > > > hba->clk_gating.active_reqs++; >> > > > - spin_unlock_irqrestore(hba->host->host_lock, flags); >> > > > - } >> > > > >> > > > hba->clk_gating.is_enabled = value; >> > > > out: >> > > > + spin_unlock_irqrestore(hba->host->host_lock, flags); >> > > > return count; >> > > > }
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