From 90d45d17f3e68608ac7ba8fc3d7acce022a19c8e Mon Sep 17 00:00:00 2001 From: Ashok Raj Date: Tue, 8 Nov 2005 21:34:24 -0800 Subject: [PATCH] cpu hotplug: fix locking in cpufreq drivers When calling target drivers to set frequency, we take cpucontrol lock. When we modified the code to accomodate CPU hotplug, there was an attempt to take a double lock of cpucontrol leading to a deadlock. Since the current thread context is already holding the cpucontrol lock, we dont need to make another attempt to acquire it. Now we leave a trace in current->flags indicating current thread already is under cpucontrol lock held, so we dont attempt to do this another time. Thanks to Andrew Morton for the beating:-) From: Brice Goglin Build fix (akpm: this patch is still unpleasant. Ashok continues to look for a cleaner solution, doesn't he? ;)) Signed-off-by: Ashok Raj Signed-off-by: Brice Goglin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 03b68a7b4b82..2bbf968b23d9 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -909,6 +909,7 @@ 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 v1.2.2