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 --- include/linux/cpu.h | 7 +++---- include/linux/sched.h | 1 - 2 files changed, 3 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/cpu.h b/include/linux/cpu.h index 43c44530ef9..0ed1d4853c6 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -65,10 +65,9 @@ extern struct sysdev_class cpu_sysdev_class; #ifdef CONFIG_HOTPLUG_CPU /* Stop CPUs going up and down. */ -extern struct semaphore cpucontrol; -#define lock_cpu_hotplug() down(&cpucontrol) -#define unlock_cpu_hotplug() up(&cpucontrol) -#define lock_cpu_hotplug_interruptible() down_interruptible(&cpucontrol) +extern void lock_cpu_hotplug(void); +extern void unlock_cpu_hotplug(void); +extern int lock_cpu_hotplug_interruptible(void); #define hotcpu_notifier(fn, pri) { \ static struct notifier_block fn##_nb = \ { .notifier_call = fn, .priority = pri }; \ diff --git a/include/linux/sched.h b/include/linux/sched.h index 2038bd27b04..b0ad6f30679 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -908,7 +908,6 @@ do { if (atomic_dec_and_test(&(tsk)->usage)) __put_task_struct(tsk); } while(0) #define PF_SYNCWRITE 0x00200000 /* I am doing a sync write */ #define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */ #define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */ -#define PF_HOTPLUG_CPU 0x01000000 /* Currently performing CPU hotplug */ /* * Only the _current_ task can read/write to tsk->flags, but other -- cgit v1.2.3