[patch 4/14] x86, ds: wait before freeing the DS configuration

[Markus Metzger <markus.t.metzger@intel.com>]

After suspending bts tracing, the task is still traced as long as it is
running. The suspend will take effect when the task is scheduled out.

Wait until the traced task becomes inactive before freeing the DS configuration.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
---

Index: git-tip/arch/x86/kernel/ds.c
===================================================================
--- git-tip.orig/arch/x86/kernel/ds.c	2009-03-27 07:59:23.000000000 +0100
+++ git-tip/arch/x86/kernel/ds.c	2009-03-27 08:00:41.000000000 +0100
@@ -783,6 +783,14 @@ void ds_release_bts(struct bts_tracer *t
 
 	ds_suspend_bts(tracer);
 
+	/*
+	 * We must wait for the suspend to take effect before we may
+	 * free the tracer and the ds configuration.
+	 */
+	if (tracer->ds.context->task &&
+	    (tracer->ds.context->task != current))
+		wait_task_inactive(tracer->ds.context->task, 0);
+
 	WARN_ON_ONCE(tracer->ds.context->bts_master != tracer);
 	tracer->ds.context->bts_master = NULL;
 
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