Commit-ID: c55f5158f5606f8a62e694b7e009f59b92ac6258 Gitweb: http://git.kernel.org/tip/c55f5158f5606f8a62e694b7e009f59b92ac6258 Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Tue, 23 Sep 2014 17:06:41 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 24 Sep 2014 14:47:05 +0200
sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSW Kirill found that there's a subtle race in the __ARCH_WANT_UNLOCKED_CTXSW code, and instead of fixing it, remove the entire exception because neither arch that uses it seems to actually still require it. Boot tested on mips64el (qemu) only. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Kirill Tkhai <tk...@yandex.ru> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Davidlohr Bueso <davidl...@hp.com> Cc: Fenghua Yu <fenghua...@intel.com> Cc: James Hogan <james.ho...@imgtec.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Paul Burton <paul.bur...@imgtec.com> Cc: Qais Yousef <qais.you...@imgtec.com> Cc: Ralf Baechle <r...@linux-mips.org> Cc: Tony Luck <tony.l...@intel.com> Cc: o...@redhat.com Cc: li...@roeck-us.net Cc: linux-i...@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-m...@linux-mips.org Link: http://lkml.kernel.org/r/20140923150641.gh3...@worktop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/ia64/include/asm/processor.h | 1 - arch/mips/include/asm/processor.h | 6 ------ kernel/sched/core.c | 6 ------ kernel/sched/sched.h | 30 ------------------------------ 4 files changed, 43 deletions(-) diff --git a/arch/ia64/include/asm/processor.h b/arch/ia64/include/asm/processor.h index c736713..ce53c50 100644 --- a/arch/ia64/include/asm/processor.h +++ b/arch/ia64/include/asm/processor.h @@ -19,7 +19,6 @@ #include <asm/ptrace.h> #include <asm/ustack.h> -#define __ARCH_WANT_UNLOCKED_CTXSW #define ARCH_HAS_PREFETCH_SWITCH_STACK #define IA64_NUM_PHYS_STACK_REG 96 diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index 05f0843..f1df4cb 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -397,12 +397,6 @@ unsigned long get_wchan(struct task_struct *p); #define ARCH_HAS_PREFETCHW #define prefetchw(x) __builtin_prefetch((x), 1, 1) -/* - * See Documentation/scheduler/sched-arch.txt; prevents deadlock on SMP - * systems. - */ -#define __ARCH_WANT_UNLOCKED_CTXSW - #endif #endif /* _ASM_PROCESSOR_H */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d65566d..5b0eac9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2331,10 +2331,6 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev) */ post_schedule(rq); -#ifdef __ARCH_WANT_UNLOCKED_CTXSW - /* In this case, finish_task_switch does not reenable preemption */ - preempt_enable(); -#endif if (current->set_child_tid) put_user(task_pid_vnr(current), current->set_child_tid); } @@ -2377,9 +2373,7 @@ context_switch(struct rq *rq, struct task_struct *prev, * of the scheduler it's an obvious special-case), so we * do an early lockdep release here: */ -#ifndef __ARCH_WANT_UNLOCKED_CTXSW spin_release(&rq->lock.dep_map, 1, _THIS_IP_); -#endif context_tracking_task_switch(prev, next); /* Here we just switch the register state and the stack. */ diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 16e1ca9..6130251 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -975,7 +975,6 @@ static inline int task_on_rq_migrating(struct task_struct *p) # define finish_arch_post_lock_switch() do { } while (0) #endif -#ifndef __ARCH_WANT_UNLOCKED_CTXSW static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) { #ifdef CONFIG_SMP @@ -1013,35 +1012,6 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) raw_spin_unlock_irq(&rq->lock); } -#else /* __ARCH_WANT_UNLOCKED_CTXSW */ -static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) -{ -#ifdef CONFIG_SMP - /* - * We can optimise this out completely for !SMP, because the - * SMP rebalancing from interrupt is the only thing that cares - * here. - */ - next->on_cpu = 1; -#endif - raw_spin_unlock(&rq->lock); -} - -static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) -{ -#ifdef CONFIG_SMP - /* - * After ->on_cpu is cleared, the task can be moved to a different CPU. - * We must ensure this doesn't happen until the switch is completely - * finished. - */ - smp_wmb(); - prev->on_cpu = 0; -#endif - local_irq_enable(); -} -#endif /* __ARCH_WANT_UNLOCKED_CTXSW */ - /* * wake flags */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
