Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6

[linux-2.6] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 38c8654aaa96b66d327a09aa2b2cf9effb49674d..49e617fa0f662a10a04980ed0f2b3997a1adc0d0 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -121,6 +121,17 @@ extern unsigned long nr_iowait(void);
 #define set_task_state(tsk, state_value)               \
        set_mb((tsk)->state, (state_value))
 
+/*
+ * set_current_state() includes a barrier so that the write of current->state
+ * is correctly serialised wrt the caller's subsequent test of whether to
+ * actually sleep:
+ *
+ *     set_current_state(TASK_UNINTERRUPTIBLE);
+ *     if (do_i_need_to_sleep())
+ *             schedule();
+ *
+ * If the caller does not need such serialisation then use __set_current_state()
+ */
 #define __set_current_state(state_value)                       \
        do { current->state = (state_value); } while (0)
 #define set_current_state(state_value)         \