diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2015-09-28 18:11:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-10-06 17:08:18 +0200 |
| commit | d87b7a33794f52226131f93cbc9db03274d9fecf (patch) | |
| tree | e1ccd2b403395dc1e9c7e5f3ba2c04960026af39 /arch | |
| parent | da7142e2ed735e1c1bef5a757dc55de35c65fbd6 (diff) | |
sched/core, sched/x86: Kill thread_info::saved_preempt_count
With the introduction of the context switch preempt_count invariant,
and the demise of PREEMPT_ACTIVE, its pointless to save/restore the
per-cpu preemption count, it must always be 2.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/preempt.h | 5 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/process_32.c | 8 | ||||
| -rw-r--r-- | arch/x86/kernel/process_64.c | 8 |
4 files changed, 1 insertions, 22 deletions
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index 01e700d392cb..01bcde84d3e4 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -30,12 +30,9 @@ static __always_inline void preempt_count_set(int pc) /* * must be macros to avoid header recursion hell */ -#define init_task_preempt_count(p) do { \ - task_thread_info(p)->saved_preempt_count = FORK_PREEMPT_COUNT; \ -} while (0) +#define init_task_preempt_count(p) do { } while (0) #define init_idle_preempt_count(p, cpu) do { \ - task_thread_info(p)->saved_preempt_count = PREEMPT_ENABLED; \ per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \ } while (0) diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 8afdc3e44247..809877e9030b 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -57,7 +57,6 @@ struct thread_info { __u32 flags; /* low level flags */ __u32 status; /* thread synchronous flags */ __u32 cpu; /* current CPU */ - int saved_preempt_count; mm_segment_t addr_limit; void __user *sysenter_return; unsigned int sig_on_uaccess_error:1; @@ -69,7 +68,6 @@ struct thread_info { .task = &tsk, \ .flags = 0, \ .cpu = 0, \ - .saved_preempt_count = INIT_PREEMPT_COUNT, \ .addr_limit = KERNEL_DS, \ } diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 737527b40e5b..9f950917528b 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -280,14 +280,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) set_iopl_mask(next->iopl); /* - * If it were not for PREEMPT_ACTIVE we could guarantee that the - * preempt_count of all tasks was equal here and this would not be - * needed. - */ - task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count); - this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count); - - /* * Now maybe handle debug registers and/or IO bitmaps */ if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index b35921a670b2..d7f1d5c4387d 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -401,14 +401,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) */ this_cpu_write(current_task, next_p); - /* - * If it were not for PREEMPT_ACTIVE we could guarantee that the - * preempt_count of all tasks was equal here and this would not be - * needed. - */ - task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count); - this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count); - /* Reload esp0 and ss1. This changes current_thread_info(). */ load_sp0(tss, next); |