static void put_ctx(struct perf_counter_context *ctx)
{
- if (atomic_dec_and_test(&ctx->refcount))
+ if (atomic_dec_and_test(&ctx->refcount)) {
+ if (ctx->parent_ctx)
+ put_ctx(ctx->parent_ctx);
kfree(ctx);
+ }
}
static void
list_add_rcu(&counter->event_entry, &ctx->event_list);
ctx->nr_counters++;
+ if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
+ ctx->nr_enabled++;
}
/*
if (list_empty(&counter->list_entry))
return;
ctx->nr_counters--;
+ if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
+ ctx->nr_enabled--;
list_del_init(&counter->list_entry);
list_del_rcu(&counter->event_entry);
cpuctx->exclusive = 0;
}
+/*
+ * Mark this context as not being a clone of another.
+ * Called when counters are added to or removed from this context.
+ * We also increment our generation number so that anything that
+ * was cloned from this context before this will not match anything
+ * cloned from this context after this.
+ */
+static void unclone_ctx(struct perf_counter_context *ctx)
+{
+ ++ctx->generation;
+ if (!ctx->parent_ctx)
+ return;
+ put_ctx(ctx->parent_ctx);
+ ctx->parent_ctx = NULL;
+}
+
/*
* Cross CPU call to remove a performance counter
*
struct perf_counter_context *ctx = counter->ctx;
struct task_struct *task = ctx->task;
+ unclone_ctx(ctx);
if (!task) {
/*
* Per cpu counters are removed via an smp call and
else
counter_sched_out(counter, cpuctx, ctx);
counter->state = PERF_COUNTER_STATE_OFF;
+ ctx->nr_enabled--;
}
spin_unlock_irqrestore(&ctx->lock, flags);
if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
update_counter_times(counter);
counter->state = PERF_COUNTER_STATE_OFF;
+ ctx->nr_enabled--;
}
spin_unlock_irq(&ctx->lock);
goto unlock;
counter->state = PERF_COUNTER_STATE_INACTIVE;
counter->tstamp_enabled = ctx->time - counter->total_time_enabled;
+ ctx->nr_enabled++;
/*
* If the counter is in a group and isn't the group leader,
counter->state = PERF_COUNTER_STATE_INACTIVE;
counter->tstamp_enabled =
ctx->time - counter->total_time_enabled;
+ ctx->nr_enabled++;
}
out:
spin_unlock_irq(&ctx->lock);
spin_unlock(&ctx->lock);
}
+/*
+ * Test whether two contexts are equivalent, i.e. whether they
+ * have both been cloned from the same version of the same context
+ * and they both have the same number of enabled counters.
+ * If the number of enabled counters is the same, then the set
+ * of enabled counters should be the same, because these are both
+ * inherited contexts, therefore we can't access individual counters
+ * in them directly with an fd; we can only enable/disable all
+ * counters via prctl, or enable/disable all counters in a family
+ * via ioctl, which will have the same effect on both contexts.
+ */
+static int context_equiv(struct perf_counter_context *ctx1,
+ struct perf_counter_context *ctx2)
+{
+ return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
+ && ctx1->parent_gen == ctx2->parent_gen
+ && ctx1->nr_enabled == ctx2->nr_enabled;
+}
+
/*
* Called from scheduler to remove the counters of the current task,
* with interrupts disabled.
* accessing the counter control register. If a NMI hits, then it will
* not restart the counter.
*/
-void perf_counter_task_sched_out(struct task_struct *task, int cpu)
+void perf_counter_task_sched_out(struct task_struct *task,
+ struct task_struct *next, int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
struct perf_counter_context *ctx = task->perf_counter_ctxp;
+ struct perf_counter_context *next_ctx;
struct pt_regs *regs;
if (likely(!ctx || !cpuctx->task_ctx))
regs = task_pt_regs(task);
perf_swcounter_event(PERF_COUNT_CONTEXT_SWITCHES, 1, 1, regs, 0);
+
+ next_ctx = next->perf_counter_ctxp;
+ if (next_ctx && context_equiv(ctx, next_ctx)) {
+ task->perf_counter_ctxp = next_ctx;
+ next->perf_counter_ctxp = ctx;
+ ctx->task = next;
+ next_ctx->task = task;
+ return;
+ }
+
__perf_counter_sched_out(ctx, cpuctx);
cpuctx->task_ctx = NULL;
if (likely(!ctx))
return;
+ if (cpuctx->task_ctx == ctx)
+ return;
__perf_counter_sched_in(ctx, cpuctx, cpu);
cpuctx->task_ctx = ctx;
}
if (IS_ERR(child_counter))
return child_counter;
+ /*
+ * Make the child state follow the state of the parent counter,
+ * not its hw_event.disabled bit. We hold the parent's mutex,
+ * so we won't race with perf_counter_{en,dis}able_family.
+ */
+ if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE)
+ child_counter->state = PERF_COUNTER_STATE_INACTIVE;
+ else
+ child_counter->state = PERF_COUNTER_STATE_OFF;
+
/*
* Link it up in the child's context:
*/
mutex_lock(&parent_counter->mutex);
list_add_tail(&child_counter->child_list, &parent_counter->child_list);
- /*
- * Make the child state follow the state of the parent counter,
- * not its hw_event.disabled bit. We hold the parent's mutex,
- * so we won't race with perf_counter_{en,dis}able_family.
- */
- if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE)
- child_counter->state = PERF_COUNTER_STATE_INACTIVE;
- else
- child_counter->state = PERF_COUNTER_STATE_OFF;
-
mutex_unlock(&parent_counter->mutex);
return child_counter;
struct perf_counter_context *child_ctx, *parent_ctx;
struct perf_counter *counter;
struct task_struct *parent = current;
+ int inherited_all = 1;
child->perf_counter_ctxp = NULL;
if (counter != counter->group_leader)
continue;
- if (!counter->hw_event.inherit)
+ if (!counter->hw_event.inherit) {
+ inherited_all = 0;
continue;
+ }
if (inherit_group(counter, parent,
- parent_ctx, child, child_ctx))
+ parent_ctx, child, child_ctx)) {
+ inherited_all = 0;
break;
+ }
+ }
+
+ if (inherited_all) {
+ /*
+ * Mark the child context as a clone of the parent
+ * context, or of whatever the parent is a clone of.
+ */
+ if (parent_ctx->parent_ctx) {
+ child_ctx->parent_ctx = parent_ctx->parent_ctx;
+ child_ctx->parent_gen = parent_ctx->parent_gen;
+ } else {
+ child_ctx->parent_ctx = parent_ctx;
+ child_ctx->parent_gen = parent_ctx->generation;
+ }
+ get_ctx(child_ctx->parent_ctx);
}
mutex_unlock(&parent_ctx->mutex);
projects / linux-beck.git / commitdiff