The patch titled
timer: permit statically-declared work with deferrable timers
has been added to the -mm tree. Its filename is
timer-permit-statically-declared-work-with-deferrable-timers.patch
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Subject: timer: permit statically-declared work with deferrable timers
From: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx>
Currently, you have to just define a delayed_work uninitialised, and then
initialise it before first use. That's a tad clumsy. At risk of playing
mind-games with the compiler, fooling it into doing pointer arithmetic
with compile-time-constants, this lets clients properly initialise delayed
work with deferrable timers statically.
This patch was inspired by the issues which lead Artem Bityutskiy to
commit 8eab945c5616fc984 ("sunrpc: make the cache cleaner workqueue
deferrable").
Signed-off-by: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx>
Acked-by: Artem Bityutskiy <Artem.Bityutskiy@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/timer.h | 25 +++++++++++++++++++++++++
include/linux/workqueue.h | 8 ++++++++
kernel/timer.c | 15 +--------------
3 files changed, 34 insertions(+), 14 deletions(-)
diff -puN include/linux/timer.h~timer-permit-statically-declared-work-with-deferrable-timers include/linux/timer.h
--- a/include/linux/timer.h~timer-permit-statically-declared-work-with-deferrable-timers
+++ a/include/linux/timer.h
@@ -48,6 +48,18 @@ extern struct tvec_base boot_tvec_bases;
#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)
#endif
+/*
+ * Note that all tvec_bases are 2 byte aligned and lower bit of
+ * base in timer_list is guaranteed to be zero. Use the LSB to
+ * indicate whether the timer is deferrable.
+ *
+ * A deferrable timer will work normally when the system is busy, but
+ * will not cause a CPU to come out of idle just to service it; instead,
+ * the timer will be serviced when the CPU eventually wakes up with a
+ * subsequent non-deferrable timer.
+ */
+#define TBASE_DEFERRABLE_FLAG (0x1)
+
#define TIMER_INITIALIZER(_function, _expires, _data) { \
.entry = { .prev = TIMER_ENTRY_STATIC }, \
.function = (_function), \
@@ -59,6 +71,19 @@ extern struct tvec_base boot_tvec_bases;
__FILE__ ":" __stringify(__LINE__)) \
}
+#define TBASE_MAKE_DEFERRED(ptr) ((struct tvec_base *) \
+ ((unsigned char *)(ptr) + TBASE_DEFERRABLE_FLAG))
+
+#define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) {\
+ .entry = { .prev = TIMER_ENTRY_STATIC }, \
+ .function = (_function), \
+ .expires = (_expires), \
+ .data = (_data), \
+ .base = TBASE_MAKE_DEFERRED(&boot_tvec_bases), \
+ __TIMER_LOCKDEP_MAP_INITIALIZER( \
+ __FILE__ ":" __stringify(__LINE__)) \
+ }
+
#define DEFINE_TIMER(_name, _function, _expires, _data) \
struct timer_list _name = \
TIMER_INITIALIZER(_function, _expires, _data)
diff -puN include/linux/workqueue.h~timer-permit-statically-declared-work-with-deferrable-timers include/linux/workqueue.h
--- a/include/linux/workqueue.h~timer-permit-statically-declared-work-with-deferrable-timers
+++ a/include/linux/workqueue.h
@@ -127,12 +127,20 @@ struct execute_work {
.timer = TIMER_INITIALIZER(NULL, 0, 0), \
}
+#define __DEFERRED_WORK_INITIALIZER(n, f) { \
+ .work = __WORK_INITIALIZER((n).work, (f)), \
+ .timer = TIMER_DEFERRED_INITIALIZER(NULL, 0, 0), \
+ }
+
#define DECLARE_WORK(n, f) \
struct work_struct n = __WORK_INITIALIZER(n, f)
#define DECLARE_DELAYED_WORK(n, f) \
struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
+#define DECLARE_DEFERRED_WORK(n, f) \
+ struct delayed_work n = __DEFERRED_WORK_INITIALIZER(n, f)
+
/*
* initialize a work item's function pointer
*/
diff -puN kernel/timer.c~timer-permit-statically-declared-work-with-deferrable-timers kernel/timer.c
--- a/kernel/timer.c~timer-permit-statically-declared-work-with-deferrable-timers
+++ a/kernel/timer.c
@@ -88,18 +88,6 @@ struct tvec_base boot_tvec_bases;
EXPORT_SYMBOL(boot_tvec_bases);
static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
-/*
- * Note that all tvec_bases are 2 byte aligned and lower bit of
- * base in timer_list is guaranteed to be zero. Use the LSB to
- * indicate whether the timer is deferrable.
- *
- * A deferrable timer will work normally when the system is busy, but
- * will not cause a CPU to come out of idle just to service it; instead,
- * the timer will be serviced when the CPU eventually wakes up with a
- * subsequent non-deferrable timer.
- */
-#define TBASE_DEFERRABLE_FLAG (0x1)
-
/* Functions below help us manage 'deferrable' flag */
static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
{
@@ -113,8 +101,7 @@ static inline struct tvec_base *tbase_ge
static inline void timer_set_deferrable(struct timer_list *timer)
{
- timer->base = ((struct tvec_base *)((unsigned long)(timer->base) |
- TBASE_DEFERRABLE_FLAG));
+ timer->base = TBASE_MAKE_DEFERRED(timer->base);
}
static inline void
_
Patches currently in -mm which might be from ext-phil.2.carmody@xxxxxxxxx are
linux-next.patch
timer-permit-statically-declared-work-with-deferrable-timers.patch
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