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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2006-05-09 22:14:28 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2006-05-09 22:14:28 +0100
commit1929ab8c6860a4a94109eed038b0fa9d12c81721 (patch)
tree42d3319df9d94cda4a514762f393c277cbdea5d3
parentf9d8f063fee645a23776519fb5c910b9d9435270 (diff)
downloadlinux-2.6.34-ux500-1929ab8c6860a4a94109eed038b0fa9d12c81721.tar.gz
[ARM] Fix thread struct allocator for SMP case
The ARM thread struct allocator is racy on SMP systems. Fix it by turning it into a per-cpu based allocator. This also allows keeps the cache cache warm for thread structs and kernel stacks. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/kernel/process.c37
1 files changed, 25 insertions, 12 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 1ff75cee4b0..1a1539e3a94 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -264,8 +264,12 @@ void show_fpregs(struct user_fp *regs)
/*
* Task structure and kernel stack allocation.
*/
-static unsigned long *thread_info_head;
-static unsigned int nr_thread_info;
+struct thread_info_list {
+ unsigned long *head;
+ unsigned int nr;
+};
+
+static DEFINE_PER_CPU(struct thread_info_list, thread_info_list) = { NULL, 0 };
#define EXTRA_TASK_STRUCT 4
@@ -274,12 +278,15 @@ struct thread_info *alloc_thread_info(struct task_struct *task)
struct thread_info *thread = NULL;
if (EXTRA_TASK_STRUCT) {
- unsigned long *p = thread_info_head;
+ struct thread_info_list *th = &get_cpu_var(thread_info_list);
+ unsigned long *p = th->head;
if (p) {
- thread_info_head = (unsigned long *)p[0];
- nr_thread_info -= 1;
+ th->head = (unsigned long *)p[0];
+ th->nr -= 1;
}
+ put_cpu_var(thread_info_list);
+
thread = (struct thread_info *)p;
}
@@ -300,13 +307,19 @@ struct thread_info *alloc_thread_info(struct task_struct *task)
void free_thread_info(struct thread_info *thread)
{
- if (EXTRA_TASK_STRUCT && nr_thread_info < EXTRA_TASK_STRUCT) {
- unsigned long *p = (unsigned long *)thread;
- p[0] = (unsigned long)thread_info_head;
- thread_info_head = p;
- nr_thread_info += 1;
- } else
- free_pages((unsigned long)thread, THREAD_SIZE_ORDER);
+ if (EXTRA_TASK_STRUCT) {
+ struct thread_info_list *th = &get_cpu_var(thread_info_list);
+ if (th->nr < EXTRA_TASK_STRUCT) {
+ unsigned long *p = (unsigned long *)thread;
+ p[0] = th->head;
+ th->head = p;
+ th->nr += 1;
+ put_cpu_var(thread_info_list);
+ return;
+ }
+ put_cpu_var(thread_info_list);
+ }
+ free_pages((unsigned long)thread, THREAD_SIZE_ORDER);
}
/*