Commit 02f72694 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched, trace: Fix sched_switch() prev_state argument

For CONFIG_PREEMPT=y kernels the sched_switch(.prev_state) argument isn't
useful because we can get preempted with current->state != TASK_RUNNING
without actually getting removed from the runqueue.

Cure this by treating all preempted tasks as runnable from the tracer's
point of view.
Signed-off-by: default avatarPeter Zijlstra <>
Cautiously-acked-by: default avatarSteven Rostedt <>
LKML-Reference: <1275322715.27810.23323.camel@twins>
Signed-off-by: default avatarIngo Molnar <>
parent e51fd5e2
...@@ -115,6 +115,23 @@ DEFINE_EVENT(sched_wakeup_template, sched_wakeup_new, ...@@ -115,6 +115,23 @@ DEFINE_EVENT(sched_wakeup_template, sched_wakeup_new,
TP_PROTO(struct task_struct *p, int success), TP_PROTO(struct task_struct *p, int success),
TP_ARGS(p, success)); TP_ARGS(p, success));
static inline long __trace_sched_switch_state(struct task_struct *p)
long state = p->state;
* For all intents and purposes a preempted task is a running task.
if (task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)
return state;
/* /*
* Tracepoint for task switches, performed by the scheduler: * Tracepoint for task switches, performed by the scheduler:
*/ */
...@@ -139,7 +156,7 @@ TRACE_EVENT(sched_switch, ...@@ -139,7 +156,7 @@ TRACE_EVENT(sched_switch,
memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
__entry->prev_pid = prev->pid; __entry->prev_pid = prev->pid;
__entry->prev_prio = prev->prio; __entry->prev_prio = prev->prio;
__entry->prev_state = prev->state; __entry->prev_state = __trace_sched_switch_state(prev);
memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
__entry->next_pid = next->pid; __entry->next_pid = next->pid;
__entry->next_prio = next->prio; __entry->next_prio = next->prio;
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