From 1929ab8c6860a4a94109eed038b0fa9d12c81721 Mon Sep 17 00:00:00 2001 From: Russell King Date: Tue, 9 May 2006 22:14:28 +0100 Subject: [PATCH] [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 --- arch/arm/kernel/process.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 1ff75ce..1a1539e 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); } /* -- 2.7.4