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Commit 1929ab8c authored by Russell King's avatar Russell King Committed by Russell King
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[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: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent f9d8f063

arch/arm/kernel/process.c

+25 −12
Original line number Diff line number Diff line
@@ -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;

	}
@@ -300,12 +307,18 @@ 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) {

	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] = (unsigned long)thread_info_head;

		thread_info_head = p;

		nr_thread_info += 1;

	} else

			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);

}