kernel.git/drivers/cpufreq/cpufreq.c, branch linux-3.8.y

cpufreq: Remove unnecessary initialization of a local variable

2012-11-14T23:33:09Z

Remove an unnecessary initializer for the 'ret' variable in __cpufreq_set_policy(). [rjw: Modified the subject and changelog slightly.] Signed-off-by: Jingoo Han Signed-off-by: Rafael J. Wysocki

cpufreq: Make sure target freq is within limits

2012-11-14T23:33:09Z

__cpufreq_driver_target() must not pass target frequency beyond the limits of current policy. Today most of cpufreq platform drivers are doing this check in their target routines. Why not move it to __cpufreq_driver_target()? Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Avoid calling cpufreq driver's target() routine if target_freq == policy->cur

2012-11-14T23:33:09Z

Avoid calling cpufreq driver's target() routine if new frequency is same as policies current frequency. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Fix sparse warning by making local function static

2012-11-14T23:33:08Z

cpufreq_disabled() is a local function, so should be marked static. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: return early from __cpufreq_driver_getavg()

2012-11-14T23:33:07Z

There is no need to do cpufreq_get_cpu() and cpufreq_put_cpu() for drivers that don't support getavg() routine. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Improve debug prints

2012-11-14T23:33:06Z

With debug options on, it is difficult to locate cpufreq core's debug prints. Fix this by prefixing debug prints with KBUILD_MODNAME. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq / core: Fix printing of governor and driver name

2012-11-14T23:33:06Z

Arrays for governer and driver name are of size CPUFREQ_NAME_LEN or 16. i.e. 15 bytes for name and 1 for trailing '\0'. When cpufreq driver print these names (for sysfs), it includes '\n' or ' ' in the fmt string and still passes length as CPUFREQ_NAME_LEN. If the driver or governor names are using all 15 fields allocated to them, then the trailing '\n' or ' ' will never be printed. And so commands like: root@linaro-developer# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver will print something like: cpufreq_foodrvroot@linaro-developer# Fix this by increasing print length by one character. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq / core: Fix typo in comment describing show_bios_limit()

2012-11-14T23:33:05Z

show_bios_limit is mistakenly written as show_scaling_driver in a comment describing purpose of show_bios_limit() routine. Fix it. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Fix sysfs deadlock with concurrent hotplug/frequency switch

2012-07-20T19:39:25Z

Running one program that continuously hotplugs and replugs a cpu concurrently with another program that continuously writes to the scaling_setspeed node eventually deadlocks with: ============================================= [ INFO: possible recursive locking detected ] 3.4.0 #37 Tainted: G W --------------------------------------------- filemonkey/122 is trying to acquire lock: (s_active#13){++++.+}, at: [] sysfs_remove_dir+0x9c/0xb4 but task is already holding lock: (s_active#13){++++.+}, at: [] sysfs_write_file+0xe8/0x140 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(s_active#13); lock(s_active#13); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by filemonkey/122: #0: (&buffer->mutex){+.+.+.}, at: [] sysfs_write_file+0x28/0x140 #1: (s_active#13){++++.+}, at: [] sysfs_write_file+0xe8/0x140 stack backtrace: [] (unwind_backtrace+0x0/0x120) from [] (validate_chain+0x6f8/0x1054) [] (validate_chain+0x6f8/0x1054) from [] (__lock_acquire+0x81c/0x8d8) [] (__lock_acquire+0x81c/0x8d8) from [] (lock_acquire+0x18c/0x1e8) [] (lock_acquire+0x18c/0x1e8) from [] (sysfs_addrm_finish+0xd0/0x180) [] (sysfs_addrm_finish+0xd0/0x180) from [] (sysfs_remove_dir+0x9c/0xb4) [] (sysfs_remove_dir+0x9c/0xb4) from [] (kobject_del+0x10/0x38) [] (kobject_del+0x10/0x38) from [] (kobject_release+0xf0/0x194) [] (kobject_release+0xf0/0x194) from [] (cpufreq_cpu_put+0xc/0x24) [] (cpufreq_cpu_put+0xc/0x24) from [] (store+0x6c/0x74) [] (store+0x6c/0x74) from [] (sysfs_write_file+0x10c/0x140) [] (sysfs_write_file+0x10c/0x140) from [] (vfs_write+0xb0/0x128) [] (vfs_write+0xb0/0x128) from [] (sys_write+0x3c/0x68) [] (sys_write+0x3c/0x68) from [] (ret_fast_syscall+0x0/0x3c) This is because store() in cpufreq.c indirectly calls kobject_get() via cpufreq_cpu_get() and is the last one to call kobject_put() via cpufreq_cpu_put(). Sysfs code should not call kobject_get() or kobject_put() directly (see the comment around sysfs_schedule_callback() for more information). Fix this deadlock by introducing two new functions: struct cpufreq_policy *cpufreq_cpu_get_sysfs(unsigned int cpu) void cpufreq_cpu_put_sysfs(struct cpufreq_policy *data) which do the same thing as cpufreq_cpu_{get,put}() but don't call kobject functions. To easily trigger this deadlock you can insert an msleep() with a reasonably large value right after the fail label at the bottom of the store() function in cpufreq.c and then write scaling_setspeed in one task and offline the cpu in another. The first task will hang and be detected by the hung task detector. Signed-off-by: Stephen Boyd Signed-off-by: Rafael J. Wysocki

provide disable_cpufreq() function to disable the API.

2012-03-14T18:45:03Z

useful for disabling cpufreq altogether. The cpu frequency scaling drivers and cpu frequency governors will fail to register. Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Dave Jones