diff options
| -rw-r--r-- | arch/ia64/kernel/perfmon.c | 4 | ||||
| -rw-r--r-- | include/linux/sched.h | 8 | ||||
| -rw-r--r-- | kernel/kthread.c | 2 | ||||
| -rw-r--r-- | kernel/ptrace.c | 2 | ||||
| -rw-r--r-- | kernel/sched.c | 29 |
5 files changed, 37 insertions, 8 deletions
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index 19d4493c619..fc8f3509df2 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -2626,7 +2626,7 @@ pfm_task_incompatible(pfm_context_t *ctx, struct task_struct *task) /* * make sure the task is off any CPU */ - wait_task_inactive(task); + wait_task_inactive(task, 0); /* more to come... */ @@ -4774,7 +4774,7 @@ recheck: UNPROTECT_CTX(ctx, flags); - wait_task_inactive(task); + wait_task_inactive(task, 0); PROTECT_CTX(ctx, flags); diff --git a/include/linux/sched.h b/include/linux/sched.h index a95d84d0da9..f59318a0099 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1882,9 +1882,13 @@ extern void set_task_comm(struct task_struct *tsk, char *from); extern char *get_task_comm(char *to, struct task_struct *tsk); #ifdef CONFIG_SMP -extern void wait_task_inactive(struct task_struct * p); +extern unsigned long wait_task_inactive(struct task_struct *, long match_state); #else -#define wait_task_inactive(p) do { } while (0) +static inline unsigned long wait_task_inactive(struct task_struct *p, + long match_state) +{ + return 1; +} #endif #define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct task_struct, tasks) diff --git a/kernel/kthread.c b/kernel/kthread.c index 6111c27491b..96cff2f8710 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -176,7 +176,7 @@ void kthread_bind(struct task_struct *k, unsigned int cpu) return; } /* Must have done schedule() in kthread() before we set_task_cpu */ - wait_task_inactive(k); + wait_task_inactive(k, 0); set_task_cpu(k, cpu); k->cpus_allowed = cpumask_of_cpu(cpu); k->rt.nr_cpus_allowed = 1; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 8392a9da645..082b3fcb32a 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -107,7 +107,7 @@ int ptrace_check_attach(struct task_struct *child, int kill) read_unlock(&tasklist_lock); if (!ret && !kill) - wait_task_inactive(child); + ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH; /* All systems go.. */ return ret; diff --git a/kernel/sched.c b/kernel/sched.c index fde1a102635..0236958addc 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1867,16 +1867,24 @@ migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req) /* * wait_task_inactive - wait for a thread to unschedule. * + * If @match_state is nonzero, it's the @p->state value just checked and + * not expected to change. If it changes, i.e. @p might have woken up, + * then return zero. When we succeed in waiting for @p to be off its CPU, + * we return a positive number (its total switch count). If a second call + * a short while later returns the same number, the caller can be sure that + * @p has remained unscheduled the whole time. + * * The caller must ensure that the task *will* unschedule sometime soon, * else this function might spin for a *long* time. This function can't * be called with interrupts off, or it may introduce deadlock with * smp_call_function() if an IPI is sent by the same process we are * waiting to become inactive. */ -void wait_task_inactive(struct task_struct *p) +unsigned long wait_task_inactive(struct task_struct *p, long match_state) { unsigned long flags; int running, on_rq; + unsigned long ncsw; struct rq *rq; for (;;) { @@ -1899,8 +1907,11 @@ void wait_task_inactive(struct task_struct *p) * return false if the runqueue has changed and p * is actually now running somewhere else! */ - while (task_running(rq, p)) + while (task_running(rq, p)) { + if (match_state && unlikely(p->state != match_state)) + return 0; cpu_relax(); + } /* * Ok, time to look more closely! We need the rq @@ -1910,9 +1921,21 @@ void wait_task_inactive(struct task_struct *p) rq = task_rq_lock(p, &flags); running = task_running(rq, p); on_rq = p->se.on_rq; + ncsw = 0; + if (!match_state || p->state == match_state) { + ncsw = p->nivcsw + p->nvcsw; + if (unlikely(!ncsw)) + ncsw = 1; + } task_rq_unlock(rq, &flags); /* + * If it changed from the expected state, bail out now. + */ + if (unlikely(!ncsw)) + break; + + /* * Was it really running after all now that we * checked with the proper locks actually held? * @@ -1944,6 +1967,8 @@ void wait_task_inactive(struct task_struct *p) */ break; } + + return ncsw; } /*** |