blk-mq: fix hang in bt_get()

Avoid that if there are fewer hardware queues than CPU threads that
bt_get() can hang. The symptoms of the hang were as follows:

* All tags allocated for a particular hardware queue.
* (nr_tags) pending commands for that hardware queue.
* No pending commands for the software queues associated with that
  hardware queue.

Signed-off-by: Jens Axboe <axboe@fb.com>
blk-mq: re-check for available tags after running the hardware queue

If we run out of tags and have to sleep, we run the hardware queue
to kick pending IO into gear. During that run, we may have completed
requests, so re-check if we have free tags before going to sleep.

Signed-off-by: Jens Axboe <axboe@fb.com>
Merge branch 'for-3.19/core' into for-next
thermal: cpu_cooling: check for the readiness of cpufreq layer

In this patch, the cpu_cooling code checks for the usability of cpufreq
layer before proceeding with the CPU cooling device registration. The
main reason is: CPU cooling device is not usable if cpufreq cannot
switch frequencies.

Similar checks are spread in thermal drivers. Thus, the advantage now
is to have the check in a single place: cpu cooling device registration.
For this reason, this patch also updates the existing drivers that
depend on CPU cooling to simply propagate the error code of the cpu
cooling registration call. Therefore, in case cpufreq is not ready, the
thermal drivers will still return -EPROBE_DEFER, in an attempt to try
again when cpufreq layer gets ready.

Cc: devicetree@vger.kernel.org
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: db8500: pass cpu_present_mask to cpufreq_cooling_register()

cpufreq_cooling_register() expects mask of all the CPUs where frequency
constraint is applicable.

This platform has more than one CPU to which these constraints will apply and so
passing mask of only CPU0 wouldn't be sufficient. Also, this platform has a
single cluster of CPUs and the constraint applies to all CPUs.

If CPU0 is hoplugged out then we may face strange BUGs as cpu_cooling framework
isn't aware of any siblings sharing clock line.

Fix it by passing cpu_present_mask to cpufreq_cooling_register().

Cc: Hongbo Zhang <hongbo.zhang@linaro.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: imx: pass cpu_present_mask to cpufreq_cooling_register()

cpufreq_cooling_register() expects mask of all the CPUs where frequency
constraint is applicable.

This platform has more than one CPU to which these constraints will apply and so
passing mask of only CPU0 wouldn't be sufficient. Also, this platform has a
single cluster of CPUs and the constraint applies to all CPUs.

If CPU0 is hoplugged out then we may face strange BUGs as cpu_cooling framework
isn't aware of any siblings sharing clock line.

Fix it by passing cpu_present_mask to cpufreq_cooling_register().

Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: exynos: pass cpu_present_mask to cpufreq_cooling_register()

cpufreq_cooling_register() expects mask of all the CPUs where frequency
constraint is applicable.

This platform has more than one CPU to which these constraints will apply and so
passing mask of only CPU0 wouldn't be sufficient. Also, this platform has a
single cluster of CPUs and the constraint applies to all CPUs.

If CPU0 is hoplugged out then we may face strange BUGs as cpu_cooling framework
isn't aware of any siblings sharing clock line.

Fix it by passing cpu_present_mask to cpufreq_cooling_register().

Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Amit Daniel Kachhap <amit.daniel@samsung.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: random comment fixups

s/give/given

Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: fix doc comment over struct cpufreq_cooling_device

cooling_cpufreq_lock isn't used to protect this structure and so the comment
over it is outdated. Fix it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: Add comment to clarify relation between cooling state and frequency

This wasn't explained well anywhere and should be clearly specified. Lets add a
top level comment for this.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: Pass variable instead of its type to sizeof()

Just following coding guidelines here.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: no need to set cpufreq_state to zero

Its already zero, we allocated cpufreq_dev with kzalloc.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: no need to set cpufreq_dev to NULL

It will be overwritten soon with return value of kzalloc().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: no need to initialze 'ret'

ret is initialized before it is used, so no need to set it to 0 in its declaration.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: propagate error returned by idr_alloc()

We aren't supposed to return our own error type here. Return what we got.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: Don't match min/max frequencies for all CPUs on cooling register

In __cpufreq_cooling_register() we try to match min/max frequencies for all CPUs
passed in 'clip_cpus' mask. This mask is the cpumask of cpus where the frequency
constraints will be applied.

Same frequency constraint can be applied only to the CPUs belonging to the same
cluster (i.e. CPUs sharing clock line). For all such CPUs we have a single
'struct cpufreq_policy' structure managing them and so getting policies for all
CPUs wouldn't make any sense as they will all return the same pointer.

So, remove this useless check of checking min/max for all CPUs. Also update doc
comment to make this more obvious that clip_cpus should be same as
policy->related_cpus.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: don't iterate over all allowed_cpus to update cpufreq policy

All CPUs present in 'allowed_cpus' share the same 'struct cpufreq_policy'
structure and so calling cpufreq_update_policy() for each of them doesn't make
sense.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: Don't check is_cpufreq_valid()

Because get_cpu_frequency() has returned a valid frequency, it means that the
cpufreq policy is surely valid and so no point checking that again with
is_cpufreq_valid(). Get rid of the routine as well as there are no more users.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: do error handling at the bottom in __cpufreq_cooling_register()

This makes life easy and bug free. And is scalable for future resource
allocations.

Acked-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
thermal: cpu_cooling: initialize 'cpufreq_val' on registration

There is no point checking for validity of 'cpufreq_val' from
cpufreq_thermal_notifier() every time the routine is called. Its guaranteed to
be 0 on the first call but will be valid otherwise.

Lets update it once while the device registers.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>