| Message ID | 20201026195124.363096-2-jaegeuk@kernel.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v4,1/5] scsi: ufs: atomic update for clkgating_enable | expand |
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? 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; > }
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. > > 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; > > }
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? 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; >> > }
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? > > 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; > > > > }
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; >> > > > }
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; }