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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2006-05-09 22:14:28 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2006-05-09 22:14:28 +0100 |
| commit | 1929ab8c6860a4a94109eed038b0fa9d12c81721 (patch) | |
| tree | 42d3319df9d94cda4a514762f393c277cbdea5d3 | |
| parent | f9d8f063fee645a23776519fb5c910b9d9435270 (diff) | |
| download | linux-1929ab8c6860a4a94109eed038b0fa9d12c81721.tar.bz2 | |
[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.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 1ff75cee4b0d..1a1539e3a946 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); } /* |