From a9d9baa1e819b2f92f9cfa5240f766c535e636a6 Mon Sep 17 00:00:00 2001 From: Ashok Raj Date: Mon, 28 Nov 2005 13:43:46 -0800 Subject: [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 Cc: Zwane Mwaikambo Cc: Shaohua Li Cc: "Siddha, Suresh B" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/cpufreq/cpufreq.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) (limited to 'drivers/cpufreq') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 1c0f62d..815902c 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; } -- cgit v1.1