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authorAshok Raj <ashok.raj@intel.com>2005-11-29 00:43:46 +0300
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-29 01:42:23 +0300
commita9d9baa1e819b2f92f9cfa5240f766c535e636a6 (patch)
tree0ae15e5b1071b395affa0ac9abf6fd746ad60b0e /drivers/cpufreq
parente0f39591cc178026607fcbbe9a53be435fe8285d (diff)
downloadlinux-a9d9baa1e819b2f92f9cfa5240f766c535e636a6.tar.xz
[PATCH] clean up lock_cpu_hotplug() in cpufreq
There are some callers in cpufreq hotplug notify path that the lowest function calls lock_cpu_hotplug(). The lock is already held during cpu_up() and cpu_down() calls when the notify calls are broadcast to registered clients. Ideally if possible, we could disable_preempt() at the highest caller and make sure we dont sleep in the path down in cpufreq->driver_target() calls but the calls are so intertwined and cumbersome to cleanup. Hence we consistently use lock_cpu_hotplug() and unlock_cpu_hotplug() in all places. - Removed export of cpucontrol semaphore and made it static. - removed explicit uses of up/down with lock_cpu_hotplug() so we can keep track of the the callers in same thread context and just keep refcounts without calling a down() that causes a deadlock. - Removed current_in_hotplug() uses - Removed PF_HOTPLUG_CPU in sched.h introduced for the current_in_hotplug() temporary workaround. Tested with insmod of cpufreq_stat.ko, and logical online/offline to make sure we dont have any hang situations. Signed-off-by: Ashok Raj <ashok.raj@intel.com> Cc: Zwane Mwaikambo <zwane@linuxpower.ca> Cc: Shaohua Li <shaohua.li@intel.com> Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq.c12
1 files changed, 2 insertions, 10 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1c0f62d0f938..815902c2c856 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1113,21 +1113,13 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
{
int retval = -EINVAL;
- /*
- * If we are already in context of hotplug thread, we dont need to
- * acquire the hotplug lock. Otherwise acquire cpucontrol to prevent
- * hotplug from removing this cpu that we are working on.
- */
- if (!current_in_cpu_hotplug())
- lock_cpu_hotplug();
-
+ lock_cpu_hotplug();
dprintk("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
target_freq, relation);
if (cpu_online(policy->cpu) && cpufreq_driver->target)
retval = cpufreq_driver->target(policy, target_freq, relation);
- if (!current_in_cpu_hotplug())
- unlock_cpu_hotplug();
+ unlock_cpu_hotplug();
return retval;
}