sched/wait: Reimplement wait_event_freezable()

Provide better implementations of wait_event_freezable() APIs.

The problem is with freezer_do_not_count(), it hides the thread from
the freezer, even though this thread might not actually freeze/sleep
at all.

Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-d86fz1jmso9wjxa8jfpinp8o@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 57 insertions, 38 deletions

diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 7fd81b8c4897..e203665c0faa 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -265,35 +265,6 @@ static inline int freezable_schedule_hrtimeout_range(ktime_t *expires,
         __retval;                                                       \
 })
 
-#define wait_event_freezable(wq, condition)                             \
-({                                                                      \
-        int __retval;                                                   \
-        freezer_do_not_count();                                         \
-        __retval = wait_event_interruptible(wq, (condition));           \
-        freezer_count();                                                \
-        __retval;                                                       \
-})
-
-#define wait_event_freezable_timeout(wq, condition, timeout)            \
-({                                                                      \
-        long __retval = timeout;                                        \
-        freezer_do_not_count();                                         \
-        __retval = wait_event_interruptible_timeout(wq, (condition),    \
-                                __retval);                              \
-        freezer_count();                                                \
-        __retval;                                                       \
-})
-
-#define wait_event_freezable_exclusive(wq, condition)                   \
-({                                                                      \
-        int __retval;                                                   \
-        freezer_do_not_count();                                         \
-        __retval = wait_event_interruptible_exclusive(wq, condition);   \
-        freezer_count();                                                \
-        __retval;                                                       \
-})
-
-
 #else /* !CONFIG_FREEZER */
 static inline bool frozen(struct task_struct *p) { return false; }
 static inline bool freezing(struct task_struct *p) { return false; }
@@ -331,15 +302,6 @@ static inline void set_freezable(void) {}
 #define freezable_schedule_hrtimeout_range(expires, delta, mode)        \
         schedule_hrtimeout_range(expires, delta, mode)
 
-#define wait_event_freezable(wq, condition)                             \
-                wait_event_interruptible(wq, condition)
-
-#define wait_event_freezable_timeout(wq, condition, timeout)            \
-                wait_event_interruptible_timeout(wq, condition, timeout)
-
-#define wait_event_freezable_exclusive(wq, condition)                   \
-                wait_event_interruptible_exclusive(wq, condition)
-
 #define wait_event_freezekillable(wq, condition)                \
                 wait_event_killable(wq, condition)
 
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 0421775e0b9f..2232ed16635a 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -267,6 +267,31 @@ do {									\
         __wait_event(wq, condition);                                    \
 } while (0)
 
+#define __wait_event_freezable(wq, condition)                           \
+        ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
+                            schedule(); try_to_freeze())
+
+/**
+ * wait_event - sleep (or freeze) until a condition gets true
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ *
+ * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
+ * to system load) until the @condition evaluates to true. The
+ * @condition is checked each time the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ */
+#define wait_event_freezable(wq, condition)                             \
+({                                                                      \
+        int __ret = 0;                                                  \
+        might_sleep();                                                  \
+        if (!(condition))                                               \
+                __ret = __wait_event_freezable(wq, condition);          \
+        __ret;                                                          \
+})
+
 #define __wait_event_timeout(wq, condition, timeout)                    \
         ___wait_event(wq, ___wait_cond_timeout(condition),              \
                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
@@ -300,6 +325,24 @@ do {									\
         __ret;                                                          \
 })
 
+#define __wait_event_freezable_timeout(wq, condition, timeout)          \
+        ___wait_event(wq, ___wait_cond_timeout(condition),              \
+                      TASK_INTERRUPTIBLE, 0, timeout,                   \
+                      __ret = schedule_timeout(__ret); try_to_freeze())
+
+/*
+ * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
+ * increasing load and is freezable.
+ */
+#define wait_event_freezable_timeout(wq, condition, timeout)            \
+({                                                                      \
+        long __ret = timeout;                                           \
+        might_sleep();                                                  \
+        if (!___wait_cond_timeout(condition))                           \
+                __ret = __wait_event_freezable_timeout(wq, condition, timeout); \
+        __ret;                                                          \
+})
+
 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
                             cmd1; schedule(); cmd2)
@@ -480,6 +523,20 @@ do {									\
 })
 
 
+#define __wait_event_freezable_exclusive(wq, condition)                 \
+        ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
+                        schedule(); try_to_freeze())
+
+#define wait_event_freezable_exclusive(wq, condition)                   \
+({                                                                      \
+        int __ret = 0;                                                  \
+        might_sleep();                                                  \
+        if (!(condition))                                               \
+                __ret = __wait_event_freezable_exclusive(wq, condition);\
+        __ret;                                                          \
+})
+
+
 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 ({                                                                      \
         int __ret = 0;                                                  \