Driver is guaranteed to be present on a call to cpufreq_parse_governor()
and there is no need to check for !cpufreq_driver. Drop it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Its always same as policy->policy, and there is no need to keep another
copy of it. Remove it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Its always same as policy->governor, and there is no need to keep
another copy of it. Remove it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
'user_policy' caches properties of a policy that are set by userspace.
And these must be updated only if cpufreq core was successful in
updating them based on request from user space.
In store_scaling_governor(), we are updating user_policy.policy and
user_policy.governor even if cpufreq_set_policy() failed. That's
incorrect.
Fix this by updating user_policy.* only if we were successful in
updating the properties.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq_get_policy() is useful if the pointer to policy isn't available
in advance. But if it is available, then there is no need to call
cpufreq_get_policy(). Directly use memcpy() to copy the policy.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
What's being done from CPUFREQ_INCOMPATIBLE, can also be done with
CPUFREQ_ADJUST. There is nothing special with CPUFREQ_INCOMPATIBLE
notifier.
Kill CPUFREQ_INCOMPATIBLE and fix its usage sites.
This also updates the numbering of notifier events to remove holes.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In some cases it wouldn't be known at time of driver registration, if
the driver needs to support boost frequencies.
For example, while getting boost information from DT with opp-v2
bindings, we need to parse the bindings for all the CPUs to know if
turbo/boost OPPs are supported or not.
One way out to do that efficiently is to delay supporting boost mode
(i.e. creating /sys/devices/system/cpu/cpufreq/boost file), until the
time OPP bindings are parsed.
At that point, the driver can enable boost support. This can be done at
->init(), where the frequency table is created.
To do that, the driver requires few APIs from cpufreq core that let him
do this. This patch provides these APIs.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This check was originally added by commit 9c9a43ed27 ("[CPUFREQ]
return error when failing to set minfreq").It attempt to return an error
on obviously incorrect limits when we echo xxx >.../scaling_max,min_freq
Actually we just need check if new_policy->min > new_policy->max.
Because at least one of max/min is copied from cpufreq_get_policy().
For example, when we echo xxx > .../scaling_min_freq, new_policy is
copied from policy in cpufreq_get_policy. new_policy->max is same with
policy->max. new_policy->min is set to a new value.
Let me explain it in deduction method, first statement in if ():
new_policy->min > policy->max
policy->max == new_policy->max
==> new_policy->min > new_policy->max
second statement in if():
new_policy->max < policy->min
policy->max < policy->min
==>new_policy->min > new_policy->max (induction method)
So we have proved that we only need check if new_policy->min >
new_policy->max.
After apply this patch, we can also modify ->min and ->max at same time
if new freq range is very much different from current freq range. For
example, if current freq range is 480000-960000, then we want to set
this range to 1120000-2240000, we would fail in the past because
new_policy->min > policy->max. As long as the cpufreq range is valid, we
has no reason to reject the user. So correct the check to avoid such
case.
Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
To protect against races with concurrent CPU online/offline, call
get_online_cpus() before registering a cpufreq driver.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
The recover_policy is unsed in cpufreq_online() to indicate whether
a new policy object is created or an existing one is reinitialized.
The "recover" part of the name is slightly confusing (it should be
"reinitialization" rather than "recovery") and the logical not (!)
operator is applied to it in almost all of the checks it is used in,
so replace that variable with a new one called "new_policy" that
will be true in the case of a new policy creation.
While at it, drop one of the labels that is jumped to from only
one spot.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
To separate the CPU online interface from the CPU device
registration, split cpufreq_online() out of cpufreq_add_dev()
and make cpufreq_cpu_callback() call the former, while
cpufreq_add_dev() itself will only be used as the CPU device
addition subsystem interface callback.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Suggested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Change cpufreq_policy_alloc() to take a CPU number instead of a CPU
device pointer as its argument, as it is the only function called by
cpufreq_add_dev() taking a device pointer argument at this point.
That will allow us to split the CPU online part from cpufreq_add_dev()
more cleanly going forward.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
The related_cpus mask includes CPUs whose cpufreq_cpu_data per-CPU
pointers have been set the the given policy. Since those pointers
are only set at the policy creation time and unset when the policy
is deleted, the related_cpus should not be updated between those
two operations.
For this reason, avoid updating it whenever the first of the
"related" CPUs goes online.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
The dev argument of cpufreq_add_policy_cpu() and
cpufreq_add_dev_interface() is not used by any of them,
so drop it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
The leftover out_release_rwsem label in cpufreq_add_dev() is not
necessary any more and confusing, so drop it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Notice that when cpufreq_policy_restore() is called, its per-CPU
cpufreq_cpu_data variable has been already dereferenced and if that
variable is not NULL, the policy local pointer in cpufreq_add_dev()
contains its value.
Therefore it is not necessary to dereference it again and the
policy pointer can be used directly. Moreover, if that pointer
is not NULL, the policy is inactive (or the previous check would
have made us return from cpufreq_add_dev()) so the restoration
code from cpufreq_policy_restore() can be moved to that point
in cpufreq_add_dev().
Do that and drop cpufreq_policy_restore().
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Since __cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
are about CPU offline rather than about CPU removal, rename them to
cpufreq_offline_prepare() and cpufreq_offline_finish(), respectively.
Also change their argument from a struct device pointer to a CPU
number, because they use the CPU number only internally anyway
and make them void as their return values are ignored.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
After commit 87549141d5 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d5 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
cpufreq_rwsem was introduced in commit 6eed9404ab ("cpufreq: Use
rwsem for protecting critical sections) in order to replace
try_module_get() on the cpu-freq driver. That try_module_get() worked
well until the refcount was so heavily used that module removal became
more or less impossible.
Though when looking at the various (undocumented) protection
mechanisms in that code, the randomly sprinkeled around cpufreq_rwsem
locking sites are superfluous.
The policy, which is acquired in cpufreq_cpu_get() and released in
cpufreq_cpu_put() is sufficiently protected already.
cpufreq_cpu_get(cpu)
/* Protects against concurrent driver removal */
read_lock_irqsave(&cpufreq_driver_lock, flags);
policy = per_cpu(cpufreq_cpu_data, cpu);
kobject_get(&policy->kobj);
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
The reference on the policy serializes versus module unload already:
cpufreq_unregister_driver()
subsys_interface_unregister()
__cpufreq_remove_dev_finish()
per_cpu(cpufreq_cpu_data) = NULL;
cpufreq_policy_put_kobj()
If there is a reference held on the policy, i.e. obtained prior to the
unregister call, then cpufreq_policy_put_kobj() will wait until that
reference is dropped. So once subsys_interface_unregister() returns
there is no policy pointer in flight and no new reference can be
obtained. So that rwsem protection is useless.
The other usage of cpufreq_rwsem in show()/store() of the sysfs
interface is redundant as well because sysfs already does the proper
kobject_get()/put() pairs.
That leaves CPU hotplug versus module removal. The current
down_write() around the write_lock() in cpufreq_unregister_driver() is
silly at best as it protects actually nothing.
The trivial solution to this is to prevent hotplug across
cpufreq_unregister_driver completely.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Return codes aren't honored properly in cpufreq_set_policy(). This can
lead to two problems:
- wrong errors propagated to sysfs
- we try to do next state-change even if the previous one failed
cpufreq_governor_dbs() now returns proper errors on all invalid
state-transition requests and this code should honor that.
Reviewed-and-tested-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq_init_policy() can fail, and we don't do anything except a call
to ->exit() on that. The policy should be freed if this happens.
Do it properly.
Reported-and-tested-by: "Jon Medhurst (Tixy)" <tixy@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
These labels are are named in two ways normally:
- Based on what caused to jump to such labels
- Based on what we do under such labels
We follow the first naming convention today and that leads to multiple
labels for doing the same work. Fix it by switching to the second way of
naming them.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Users of freq table may want to access it for any CPU from
policy->related_cpus mask. One such user is cpu-cooling layer. It gets a
list of 'clip_cpus' (equivalent to policy->related_cpus) during
registration and tries to get freq_table for the first CPU of this mask.
If the CPU, for which it tries to fetch freq_table, is offline,
cpufreq_frequency_get_table() fails. This happens because it relies on
cpufreq_cpu_get_raw() for its functioning which returns policy only for
online CPUs.
The fix is to access the policy data structure for the given CPU
directly (which also returns a valid policy for offline CPUs), but the
policy itself has to be active (meaning that at least one CPU using it
is online) for the frequency table to be returned.
Because we will be using 'cpufreq_cpu_data' now, which is internal to
the cpufreq core, move cpufreq_frequency_get_table() to cpufreq.c.
Reported-and-tested-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When all CPUs of a policy are hot-unplugged, we EXIT the governor but
don't mark policy->governor as NULL. This was done in order to keep last
used governor's information intact in sysfs, while the CPUs are offline.
But we also need to clear policy->governor when restoring the policy.
Because policy->governor still points to the last governor while policy
is restored, following sequence of event happens:
- cpufreq_init_policy() called while restoring policy
- find_governor() matches last_governor string for present governors and
returns last used governor's pointer, say ondemand. policy->governor
already has the same address, unless the governor was removed in
between.
- cpufreq_set_policy() is called with both old/new policies governor set
as ondemand.
- Because governors matched, we skip governor initialization and return
after calling __cpufreq_governor(CPUFREQ_GOV_LIMITS). Because the
governor wasn't initialized for this policy, it returned -EBUSY.
- cpufreq_init_policy() exits the policy on this error, but doesn't
destroy it properly (should be fixed separately).
- And so we enter a scenario where the policy isn't completely
initialized but used.
Fix this by setting policy->governor to NULL while restoring the policy.
Reported-and-tested-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org>
Reported-and-tested-by: "Jon Medhurst (Tixy)" <tixy@linaro.org>
Reported-and-tested-by: Steven Rostedt <rostedt@goodmis.org>
Fixes: 18bf3a124e (cpufreq: Mark policy->governor = NULL for inactive policies)
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq_update_policy() was kept as a separate routine earlier as it was
handling migration of sysfs directories, which isn't the case anymore.
It is only updating policy->cpu now and is called by a single caller.
The WARN_ON() isn't really required anymore, as we are just updating the
cpu now, not moving the sysfs directories.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
__cpufreq_remove_dev_finish() is doing two things today:
- Restarts the governor if some CPUs from concerned policy are still
online.
- Frees the policy if all CPUs are offline.
The first task of restarting the governor can be moved to
__cpufreq_remove_dev_prepare() to restart the governor early. There is
no race between _prepare() and _finish() as they would be handling
completely different cases. _finish() will only be required if we are
going to free the policy and that has nothing to do with restarting the
governor.
Original-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq_policy_put_kobj() is actually part of freeing the policy and can
be called from cpufreq_policy_free() directly instead of a separate
call.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
policy->kobj is required to be initialized once in the lifetime of a
policy. Currently we are initializing it from __cpufreq_add_dev() and
that doesn't look to be the best place for doing so as we have to do
this on special cases (like: !recover_policy).
We can initialize it from a more obvious place cpufreq_policy_alloc()
and that will make code look cleaner, specially the error handling part.
The error handling part of __cpufreq_add_dev() was doing almost the same
thing while recover_policy is true or false. Fix that as well by always
calling cpufreq_policy_put_kobj() with an additional parameter to skip
notification part of it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When we hot-unplug a cpu, we remove its sysfs cpufreq directory and if
the outgoing cpu was the owner of policy->kobj earlier then we migrate
the sysfs directory to under another online cpu.
There are few disadvantages this brings:
- Code Complexity
- Slower hotplug/suspend/resume
- sysfs file permissions are reset after all policy->cpus are offlined
- CPUFreq stats history lost after all policy->cpus are offlined
- Special management of sysfs stuff during suspend/resume
To overcome these, this patch modifies the way sysfs directories are
managed:
- Select sysfs kobjects owner while initializing policy and don't change
it during hotplugs. Track it with kobj_cpu created earlier.
- Create symlinks for all related CPUs (can be offline) instead of
affected CPUs on policy initialization and remove them only when the
policy is freed.
- Free policy structure only on the removal of cpufreq-driver and not
during hotplug/suspend/resume, detected by checking 'struct
subsys_interface *' (Valid only when called from
subsys_interface_unregister() while unregistering driver).
Apart from this, special care is taken to handle physical hoplug of CPUs
as we wouldn't remove sysfs links or remove policies on logical
hotplugs. Physical hotplug happens in the following sequence.
Hot removal:
- CPU is offlined first, ~ 'echo 0 >
/sys/devices/system/cpu/cpuX/online'
- Then its device is removed along with all sysfs files, cpufreq core
notified with cpufreq_remove_dev() callback from subsys-interface..
Hot addition:
- First the device along with its sysfs files is added, cpufreq core
notified with cpufreq_add_dev() callback from subsys-interface..
- CPU is onlined, ~ 'echo 1 > /sys/devices/system/cpu/cpuX/online'
We call the same routines with both hotplug and subsys callbacks, and we
sense physical hotplug with cpu_offline() check in subsys callback. We
can handle most of the stuff with regular hotplug callback paths and
add/remove cpufreq sysfs links or free policy from subsys callbacks.
Original-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Later commits would change the way policies are managed today. Policies
wouldn't be freed on cpu hotplug (currently they aren't freed only for
suspend), and while the CPU is offline, the sysfs cpufreq files would
still be present.
User may accidentally try to update the sysfs files in following
directory: '/sys/devices/system/cpu/cpuX/cpufreq/'. And that would
result in undefined behavior as policy wouldn't be active then.
Apart from updating the store() routine, we also update __cpufreq_get()
which can call cpufreq_out_of_sync(). The later routine tries to update
policy->cur and starts notifying kernel about it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In order to prepare for the next few commits, that will stop migrating
sysfs files on cpu hotplug, this patch starts managing sysfs-cpu
separately.
The behavior is still the same as we are still migrating sysfs files on
hotplug, later commits would change that.
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Later commits would change the way policies are managed today. Policies
wouldn't be freed on cpu hotplug (currently they aren't freed on
suspend), and while the CPU is offline, the sysfs cpufreq files would
still be present.
Because we don't mark policy->governor as NULL, it still contains
pointer of the last used governor. And if the governor is removed, while
all the CPUs of a policy are hotplugged out, this pointer wouldn't be
valid anymore. And if we try to read the 'scaling_governor', etc. from
sysfs, it will result in kernel OOPs.
To prevent this, mark policy->governor as NULL for all inactive policies
while the governor is removed from kernel.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
History of which governor was used last is common to all CPUs within a
policy and maintaining it per-cpu isn't the best approach for sure.
Apart from wasting memory, this also increases the complexity of
managing this data structure as it has to be updated for all CPUs.
To make that somewhat simpler, lets store this information in a new
field 'last_governor' in struct cpufreq_policy and update it on removal
of last cpu of a policy.
As a side-effect it also solves an old problem, consider a system with
two clusters 0 & 1. And there is one policy per cluster.
Cluster 0: CPU0 and 1.
Cluster 1: CPU2 and 3.
- CPU2 is first brought online, and governor is set to performance
(default as cpufreq_cpu_governor wasn't set).
- Governor is changed to ondemand.
- CPU2 is taken offline and cpufreq_cpu_governor is updated for CPU2.
- CPU3 is brought online.
- Because cpufreq_cpu_governor wasn't set for CPU3, the default governor
performance is picked for CPU3.
This patch fixes the bug as we now have a single variable to update for
policy.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
We reach here while adding policy for a CPU and enter into the 'if'
block only if a policy already exists for the CPU.
As cpufreq_cpu_data is set for all policy->related_cpus now, when the
policy is first added, we can use that to find the CPU's policy instead
of traversing the list of all active policies.
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
We can extract the same information from cpufreq_cpu_data as it is also
available for inactive policies now. And so don't need
cpufreq_cpu_data_fallback anymore.
Also add a WARN_ON() for the case where we try to restore from an active
policy.
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Now that we can check policy->cpus to find if policy is active or not,
we don't need to clean cpufreq_cpu_data and delete policy from the list
on light weight tear down of policies (like in suspend).
To make it consistent and clean, set cpufreq_cpu_data for all related
CPUs when the policy is first created and clean it only while it is
freed.
Also update cpufreq_cpu_get_raw() to check if cpu is part of
policy->cpus mask, so that we don't end up getting policies for offline
CPUs.
In order to make sure that no users of 'policy' are using an inactive
policy, use cpufreq_cpu_get_raw() instead of directly accessing
cpufreq_cpu_data.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
policy->cpus is cleared unconditionally now on hotplug-out of a CPU and
it can be checked to know if a policy is active or not. Create helper
routines to iterate over all active/inactive policies, based on
policy->cpus field.
Replace all instances of for_each_policy() with for_each_active_policy()
to make them iterate only for active policies. (We haven't made changes
yet to keep inactive policies in the same list, but that will be
followed in a later patch).
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
We clear policy->cpus mask while CPUs are hotplugged out. We do it for all CPUs
except the last CPU of the policy. I don't remember what the rationale behind
that was, but I couldn't think of anything that will break if we remove this
conditional clearing and always clear policy->cpus.
The benefit we get out of it is, we can know if a policy is active or not by
checking if this field is empty or not. That will be used by later commits.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
There are two cases when we may try to add CPUs we're already handling:
- On boot, the first cpu has marked all policy->cpus managed and so we
will find policy for all other policy->cpus later on.
- When a managed cpu is hotplugged out and later brought back in.
Currently, separate paths and checks take care of the two. While the
first one is detected by testing cpu against 'policy->cpus', the other
one is detected by testing cpu against 'policy->related_cpus'.
We can handle them both via a single path and there is no need to do
special checking for the first one.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
[ rjw: Changelog, comments ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Simply returning here with an error is not enough. It shouldn't be allowed at
all to try calling cpufreq_cpu_get() for an invalid CPU.
Add a WARN here to make it clear that it wouldn't be acceptable at all.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq_add_dev() is an unnecessary wrapper over __cpufreq_add_dev(). Merge
them.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This clearly states what the code inside these routines is doing and how these
must be used.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
All CPUs leaving the first-online CPU are hotplugged out on suspend and
and cpufreq core stops managing them.
On resume, we need to call cpufreq_update_policy() for this CPU's policy
to make sure its frequency is in sync with cpufreq's cached value, as it
might have got updated by hardware during suspend/resume.
The policies are always added to the top of the policy-list. So, in
normal circumstances, CPU 0's policy will be the last one in the list.
And so the code checks for the last policy.
But there are cases where it will fail. Consider quad-core system, with
policy-per core. If CPU0 is hotplugged out and added back again, the
last policy will be on CPU1 :(
To fix this in a proper way, always look for the policy of the first
online CPU. That way we will be sure that we are calling
cpufreq_update_policy() for the only CPU that wasn't hotplugged out.
Cc: 3.15+ <stable@vger.kernel.org> # 3.15+
Fixes: 2f0aea9363 ("cpufreq: suspend governors on system suspend/hibernate")
Reported-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
To make code more readable and less error prone, lets create a helper macro for
iterating over all available governors.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
To make code more readable and less error prone, lets create a helper macro for
iterating over all active policies.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When cpufreq is disabled, the per-cpu variable would have been set to
NULL. Remove this unnecessary check.
[ Changelog from Saravana Kannan. ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In __cpufreq_remove_dev_finish(), per-cpu 'cpufreq_cpu_data' needs
to be cleared before calling kobject_put(&policy->kobj) and under
cpufreq_driver_lock. Otherwise, if someone else calls cpufreq_cpu_get()
in parallel with it, they can obtain a non-NULL policy from that after
kobject_put(&policy->kobj) was executed.
Consider this case:
Thread A Thread B
cpufreq_cpu_get()
acquire cpufreq_driver_lock
read-per-cpu cpufreq_cpu_data
kobject_put(&policy->kobj);
kobject_get(&policy->kobj);
...
per_cpu(&cpufreq_cpu_data, cpu) = NULL
And this will result in a warning like this one:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4 at include/linux/kref.h:47
kobject_get+0x41/0x50()
Modules linked in: acpi_cpufreq(+) nfsd auth_rpcgss nfs_acl
lockd grace sunrpc xfs libcrc32c sd_mod ixgbe igb mdio ahci hwmon
...
Call Trace:
[<ffffffff81661b14>] dump_stack+0x46/0x58
[<ffffffff81072b61>] warn_slowpath_common+0x81/0xa0
[<ffffffff81072c7a>] warn_slowpath_null+0x1a/0x20
[<ffffffff812e16d1>] kobject_get+0x41/0x50
[<ffffffff815262a5>] cpufreq_cpu_get+0x75/0xc0
[<ffffffff81527c3e>] cpufreq_update_policy+0x2e/0x1f0
[<ffffffff810b8cb2>] ? up+0x32/0x50
[<ffffffff81381aa9>] ? acpi_ns_get_node+0xcb/0xf2
[<ffffffff81381efd>] ? acpi_evaluate_object+0x22c/0x252
[<ffffffff813824f6>] ? acpi_get_handle+0x95/0xc0
[<ffffffff81360967>] ? acpi_has_method+0x25/0x40
[<ffffffff81391e08>] acpi_processor_ppc_has_changed+0x77/0x82
[<ffffffff81089566>] ? move_linked_works+0x66/0x90
[<ffffffff8138e8ed>] acpi_processor_notify+0x58/0xe7
[<ffffffff8137410c>] acpi_ev_notify_dispatch+0x44/0x5c
[<ffffffff8135f293>] acpi_os_execute_deferred+0x15/0x22
[<ffffffff8108c910>] process_one_work+0x160/0x410
[<ffffffff8108d05b>] worker_thread+0x11b/0x520
[<ffffffff8108cf40>] ? rescuer_thread+0x380/0x380
[<ffffffff81092421>] kthread+0xe1/0x100
[<ffffffff81092340>] ? kthread_create_on_node+0x1b0/0x1b0
[<ffffffff81669ebc>] ret_from_fork+0x7c/0xb0
[<ffffffff81092340>] ? kthread_create_on_node+0x1b0/0x1b0
---[ end trace 89e66eb9795efdf7 ]---
The actual code flow is as follows:
Thread A: Workqueue: kacpi_notify
acpi_processor_notify()
acpi_processor_ppc_has_changed()
cpufreq_update_policy()
cpufreq_cpu_get()
kobject_get()
Thread B: xenbus_thread()
xenbus_thread()
msg->u.watch.handle->callback()
handle_vcpu_hotplug_event()
vcpu_hotplug()
cpu_down()
__cpu_notify(CPU_POST_DEAD..)
cpufreq_cpu_callback()
__cpufreq_remove_dev_finish()
cpufreq_policy_put_kobj()
kobject_put()
cpufreq_cpu_get() gets the policy from per-cpu variable cpufreq_cpu_data
under cpufreq_driver_lock, and once it gets a valid policy it expects it
to not be freed until cpufreq_cpu_put() is called.
But the race happens when another thread puts the kobject first and updates
cpufreq_cpu_data before or later. And so the first thread gets a valid policy
structure and before it does kobject_get() on it, the second one has already
done kobject_put().
Fix this by setting cpufreq_cpu_data to NULL before putting the kobject and that
too under locks.
Reported-by: Ethan Zhao <ethan.zhao@oracle.com>
Reported-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 3.12+ <stable@vger.kernel.org> # 3.12+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Rafael J. Wysocki