| Message ID | 1516955899-31810-1-git-send-email-baijiaju1990@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote: > After checking all possible call chains to genpd_dev_pm_detach() and > genpd_dev_pm_attach() here, > my tool finds that these functions are never called in atomic context, > namely never in an interrupt handler or holding a spinlock. > Thus mdelay can be replaced with msleep to avoid busy wait. > > This is found by a static analysis tool named DCNS written by myself. Well, cond_resched() just after msleep certainly looks like that. Did the patch receive any testing? > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > drivers/base/power/domain.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > index 0c80bea..f84ac72 100644 > --- a/drivers/base/power/domain.c > +++ b/drivers/base/power/domain.c > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off) > if (ret != -EAGAIN) > break; > > - mdelay(i); > + msleep(i); > cond_resched(); > } > > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev) > if (ret != -EAGAIN) > break; > > - mdelay(i); > + msleep(i); > cond_resched(); > } > mutex_unlock(&gpd_list_lock);
On 2018/1/26 18:26, Pavel Machek wrote: > On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote: >> After checking all possible call chains to genpd_dev_pm_detach() and >> genpd_dev_pm_attach() here, >> my tool finds that these functions are never called in atomic context, >> namely never in an interrupt handler or holding a spinlock. >> Thus mdelay can be replaced with msleep to avoid busy wait. >> >> This is found by a static analysis tool named DCNS written by > myself. > > Well, cond_resched() just after msleep certainly looks like that. > > Did the patch receive any testing? > Thanks for reply :) I only perform compilation testing but did not run it in real execution. Thanks, Jia-Ju Bai
On Friday, January 26, 2018 9:38:19 AM CET Jia-Ju Bai wrote: > After checking all possible call chains to genpd_dev_pm_detach() and > genpd_dev_pm_attach() here, > my tool finds that these functions are never called in atomic context, > namely never in an interrupt handler or holding a spinlock. > Thus mdelay can be replaced with msleep to avoid busy wait. > > This is found by a static analysis tool named DCNS written by myself. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > drivers/base/power/domain.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > index 0c80bea..f84ac72 100644 > --- a/drivers/base/power/domain.c > +++ b/drivers/base/power/domain.c > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off) > if (ret != -EAGAIN) > break; > > - mdelay(i); > + msleep(i); > cond_resched(); > } > > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev) > if (ret != -EAGAIN) > break; > > - mdelay(i); > + msleep(i); > cond_resched(); > } > mutex_unlock(&gpd_list_lock); > Ulf, Kevin, any concerns or objections?
On 26 January 2018 at 09:38, Jia-Ju Bai <baijiaju1990@gmail.com> wrote: > After checking all possible call chains to genpd_dev_pm_detach() and > genpd_dev_pm_attach() here, > my tool finds that these functions are never called in atomic context, > namely never in an interrupt handler or holding a spinlock. > Thus mdelay can be replaced with msleep to avoid busy wait. > > This is found by a static analysis tool named DCNS written by myself. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > drivers/base/power/domain.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > index 0c80bea..f84ac72 100644 > --- a/drivers/base/power/domain.c > +++ b/drivers/base/power/domain.c > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off) > if (ret != -EAGAIN) > break; > > - mdelay(i); > + msleep(i); This looks like a nice improvement, however moving to msleep() makes the call to cond_resched() below a bit superfluous. Perhaps remove that as well. > cond_resched(); > } > > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev) > if (ret != -EAGAIN) > break; > > - mdelay(i); > + msleep(i); Ditto. > cond_resched(); > } > mutex_unlock(&gpd_list_lock); > -- > 1.7.9.5 > Kind regards Uffe
Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson: > On 26 January 2018 at 09:38, Jia-Ju Bai <baijiaju1990@gmail.com> > wrote: > > After checking all possible call chains to genpd_dev_pm_detach() > > and > > genpd_dev_pm_attach() here, > > my tool finds that these functions are never called in atomic > > context, > > namely never in an interrupt handler or holding a spinlock. > > Thus mdelay can be replaced with msleep to avoid busy wait. > > > > This is found by a static analysis tool named DCNS written by > > myself. > > > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > > --- > > drivers/base/power/domain.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/base/power/domain.c > > b/drivers/base/power/domain.c > > index 0c80bea..f84ac72 100644 > > --- a/drivers/base/power/domain.c > > +++ b/drivers/base/power/domain.c > > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device > > *dev, bool power_off) > > if (ret != -EAGAIN) > > break; > > > > - mdelay(i); > > + msleep(i); > > This looks like a nice improvement, however moving to msleep() makes > the call to cond_resched() below a bit superfluous. Perhaps remove > that as well. At least for small values of i, msleep also has a high chance to overshoot the desired sleep by a lot. It would be better to convert them to usleep_range with an acceptable slack. Regards, Lucas > > cond_resched(); > > } > > > > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev) > > if (ret != -EAGAIN) > > break; > > > > - mdelay(i); > > + msleep(i); > > Ditto. > > > cond_resched(); > > } > > mutex_unlock(&gpd_list_lock); > > -- > > 1.7.9.5 > > > > Kind regards > Uffe
On 12 February 2018 at 11:38, Lucas Stach <l.stach@pengutronix.de> wrote: > Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson: >> On 26 January 2018 at 09:38, Jia-Ju Bai <baijiaju1990@gmail.com> >> wrote: >> > After checking all possible call chains to genpd_dev_pm_detach() >> > and >> > genpd_dev_pm_attach() here, >> > my tool finds that these functions are never called in atomic >> > context, >> > namely never in an interrupt handler or holding a spinlock. >> > Thus mdelay can be replaced with msleep to avoid busy wait. >> > >> > This is found by a static analysis tool named DCNS written by >> > myself. >> > >> > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> >> > --- >> > drivers/base/power/domain.c | 4 ++-- >> > 1 file changed, 2 insertions(+), 2 deletions(-) >> > >> > diff --git a/drivers/base/power/domain.c >> > b/drivers/base/power/domain.c >> > index 0c80bea..f84ac72 100644 >> > --- a/drivers/base/power/domain.c >> > +++ b/drivers/base/power/domain.c >> > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device >> > *dev, bool power_off) >> > if (ret != -EAGAIN) >> > break; >> > >> > - mdelay(i); >> > + msleep(i); >> >> This looks like a nice improvement, however moving to msleep() makes >> the call to cond_resched() below a bit superfluous. Perhaps remove >> that as well. > > At least for small values of i, msleep also has a high chance to > overshoot the desired sleep by a lot. It would be better to convert > them to usleep_range with an acceptable slack. Ack! [...] Kind regards Uffe
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 0c80bea..f84ac72 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off) if (ret != -EAGAIN) break; - mdelay(i); + msleep(i); cond_resched(); } @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev) if (ret != -EAGAIN) break; - mdelay(i); + msleep(i); cond_resched(); } mutex_unlock(&gpd_list_lock);
After checking all possible call chains to genpd_dev_pm_detach() and genpd_dev_pm_attach() here, my tool finds that these functions are never called in atomic context, namely never in an interrupt handler or holding a spinlock. Thus mdelay can be replaced with msleep to avoid busy wait. This is found by a static analysis tool named DCNS written by myself. Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> --- drivers/base/power/domain.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)