| Message ID | BEC9F67575FA1E429CA7CF5AE9BE363432A46913@SHSMSX104.ccr.corp.intel.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Thu, May 04, 2017 at 09:00:52AM +0000, Li, Fei wrote: > In case of there is no cpuidle devices registered, dev will be null, and > panic will be triggered like below; > In this patch, add checking of dev before usage, like that done in > cpuidle_idle_call. > > Panic without fix: > [ 184.961328] BUG: unable to handle kernel NULL pointer dereference at > (null) > [ 184.961328] IP: cpuidle_use_deepest_state+0x30/0x60 > ... > [ 184.961328] play_idle+0x8d/0x210 > [ 184.961328] ? __schedule+0x359/0x8e0 > [ 184.961328] ? _raw_spin_unlock_irqrestore+0x28/0x50 > [ 184.961328] ? kthread_queue_delayed_work+0x41/0x80 > [ 184.961328] clamp_idle_injection_func+0x64/0x1e0 > > Fixes: bb8313b603eb8 ("cpuidle: Allow enforcing deepest idle state selection") > Signed-off-by: Li, Fei <fei.li@intel.com> > Tested-by: Shi, Feng <fengx.shi@intel.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Reviewed-by: Koul, Vinod <vinod.koul@intel.com> > --- > drivers/cpuidle/cpuidle.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 548b90b..2706be7 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -111,7 +111,8 @@ void cpuidle_use_deepest_state(bool enable) > > preempt_disable(); > dev = cpuidle_get_device(); > - dev->use_deepest_state = enable; > + if (dev) > + dev->use_deepest_state = enable; This change is acceptable as a hot fix but the question is 'why is this function called if there is no cpuidle driver registered?' > preempt_enable(); > } > > -- > 1.9.1 > > Best Regards, > Fei
On Thursday, May 4, 2017 6:16 PM Daniel Lezcano wrote: > > > > preempt_disable(); > > dev = cpuidle_get_device(); > > - dev->use_deepest_state = enable; > > + if (dev) > > + dev->use_deepest_state = enable; > > > This change is acceptable as a hot fix but the question is 'why is this > function called if there is no cpuidle driver registered?' It's called as below: clamp_idle_injection_func -> play_idle -> cpuidle_use_deepest_state In play_idle, if no cpuidle driver registered, cpu_idle_poll can be called. It seems to go too far if not calling play_idle in case of no cpuidle driver registered. At present no other suitable and simple fix seen. > > > preempt_enable(); > > } > > > > -- > > 1.9.1 > > > > Best Regards, > > Fei > > -- > > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog Best Regards, Fei
On Thursday, May 04, 2017 09:00:52 AM Li, Fei wrote: > In case of there is no cpuidle devices registered, dev will be null, and > panic will be triggered like below; > In this patch, add checking of dev before usage, like that done in > cpuidle_idle_call. > > Panic without fix: > [ 184.961328] BUG: unable to handle kernel NULL pointer dereference at > (null) > [ 184.961328] IP: cpuidle_use_deepest_state+0x30/0x60 > ... > [ 184.961328] play_idle+0x8d/0x210 > [ 184.961328] ? __schedule+0x359/0x8e0 > [ 184.961328] ? _raw_spin_unlock_irqrestore+0x28/0x50 > [ 184.961328] ? kthread_queue_delayed_work+0x41/0x80 > [ 184.961328] clamp_idle_injection_func+0x64/0x1e0 > > Fixes: bb8313b603eb8 ("cpuidle: Allow enforcing deepest idle state selection") > Signed-off-by: Li, Fei <fei.li@intel.com> > Tested-by: Shi, Feng <fengx.shi@intel.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Reviewed-by: Koul, Vinod <vinod.koul@intel.com> > --- > drivers/cpuidle/cpuidle.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 548b90b..2706be7 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -111,7 +111,8 @@ void cpuidle_use_deepest_state(bool enable) > > preempt_disable(); > dev = cpuidle_get_device(); > - dev->use_deepest_state = enable; > + if (dev) > + dev->use_deepest_state = enable; > preempt_enable(); > } > > -- > 1.9.1 A previous version of this has been applied and I don't see any differences in the code changes. Thanks, Rafael
On Sat, May 6, 2017 at 12:33 AM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > On Thursday, May 04, 2017 09:00:52 AM Li, Fei wrote: >> Fixes: bb8313b603eb8 ("cpuidle: Allow enforcing deepest idle state selection") >> Signed-off-by: Li, Fei <fei.li@intel.com> >> Tested-by: Shi, Feng <fengx.shi@intel.com> >> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> >> Reviewed-by: Koul, Vinod <vinod.koul@intel.com> > A previous version of this has been applied and I don't see any differences > in the code changes. AFAIR only tags (above) had been extended in v3.
> >> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > >> Reviewed-by: Koul, Vinod <vinod.koul@intel.com> > > > A previous version of this has been applied and I don't see any differences > > in the code changes. > > AFAIR only tags (above) had been extended in v3. Thanks. Yes, for v3 no change in code, and only tags "Reviewed-by" added. > > -- > With Best Regards, > Andy Shevchenko Best Regards, Fei
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 548b90b..2706be7 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -111,7 +111,8 @@ void cpuidle_use_deepest_state(bool enable) preempt_disable(); dev = cpuidle_get_device(); - dev->use_deepest_state = enable; + if (dev) + dev->use_deepest_state = enable; preempt_enable(); }
In case of there is no cpuidle devices registered, dev will be null, and panic will be triggered like below; In this patch, add checking of dev before usage, like that done in cpuidle_idle_call. Panic without fix: [ 184.961328] BUG: unable to handle kernel NULL pointer dereference at (null) [ 184.961328] IP: cpuidle_use_deepest_state+0x30/0x60 ... [ 184.961328] play_idle+0x8d/0x210 [ 184.961328] ? __schedule+0x359/0x8e0 [ 184.961328] ? _raw_spin_unlock_irqrestore+0x28/0x50 [ 184.961328] ? kthread_queue_delayed_work+0x41/0x80 [ 184.961328] clamp_idle_injection_func+0x64/0x1e0 Fixes: bb8313b603eb8 ("cpuidle: Allow enforcing deepest idle state selection") Signed-off-by: Li, Fei <fei.li@intel.com> Tested-by: Shi, Feng <fengx.shi@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Koul, Vinod <vinod.koul@intel.com> --- drivers/cpuidle/cpuidle.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 1.9.1 Best Regards, Fei