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[ARM] Fix thread struct allocator for SMP case

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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>
This commit is contained in:
Russell King 2006-05-09 22:14:28 +01:00 committed by Russell King
parent f9d8f063fe
commit 1929ab8c68
1 changed files with 25 additions and 12 deletions
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37
arch/arm/kernel/process.c
View file

@ -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);
}
/*