[PATCH] posix-timers: CPU clock support for POSIX timers

POSIX requires that when you claim _POSIX_CPUTIME and _POSIX_THREAD_CPUTIME,
not only the clock_* calls but also timer_* calls must support the thread and
process CPU time clocks.  This patch provides that support, building on my
recent additions to support these clocks in the POSIX clock_* interfaces.
This patch will not work without those changes, as well as the patch fixing
the timer lock-siglock deadlock problem.

The apparent pervasive changes to posix-timers.c are simply that some fields
of struct k_itimer have changed name and moved into a union.  This was
appropriate since the data structures required for the existing real-time
timer support and for the new thread/process CPU-time timers are quite
different.

The glibc patches to support CPU time clocks using the new kernel support is
in http://people.redhat.com/roland/glibc/kernel-cpuclocks.patch, and that
includes tests for the timer support (if you build glibc with NPTL).
From: Christoph Lameter <clameter@sgi.com>

  Your patch breaks the mmtimer driver because it used k_itimer values for
  its own purposes.  Here is a fix by defining an additional structure in
  k_itimer (same approach for mmtimer as the cpu timers):
From: Roland McGrath <roland@redhat.com>

Fix bug identified by Alexander Nyberg <alexn@dsv.su.se>

> The problem arises from code touching the union in alloc_posix_timer()
> which makes firing go non-zero. When firing is checked in
> posix_cpu_timer_set() it will be positive causing an infinite loop.
>
> So either the below fix or preferably move the INIT_LIST_HEAD(x) from
> alloc_posix_timer() to somewhere later where it doesn't disturb the other
> union members.

Thanks for finding this problem.  The latter is what I think is the right
solution.  This patch does that, and also removes some superfluous rezeroing.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 57 insertions, 10 deletions

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 6498e9da9ce6..aa1eb2d45ed8 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -51,6 +51,7 @@
 		.list = LIST_HEAD_INIT(sig.shared_pending.list),	\
 		.signal =  {{0}}}, \
 	.posix_timers	 = LIST_HEAD_INIT(sig.posix_timers),		\
+	.cpu_timers	= INIT_CPU_TIMERS(sig.cpu_timers),		\
 	.rlim		= INIT_RLIMITS,					\
 }
 
@@ -112,8 +113,16 @@ extern struct group_info init_groups;
 	.proc_lock	= SPIN_LOCK_UNLOCKED,				\
 	.switch_lock	= SPIN_LOCK_UNLOCKED,				\
 	.journal_info	= NULL,						\
+	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
 }
 
 
+#define INIT_CPU_TIMERS(cpu_timers)					\
+{									\
+	LIST_HEAD_INIT(cpu_timers[0]),					\
+	LIST_HEAD_INIT(cpu_timers[1]),					\
+	LIST_HEAD_INIT(cpu_timers[2]),					\
+}
+
 
 #endif
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index a0140c8f72b7..2820fd4ab58b 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -3,8 +3,21 @@
 
 #include <linux/spinlock.h>
 #include <linux/list.h>
+#include <linux/sched.h>
 
-#define CPUCLOCK_PID(clock)	((pid_t) ~((clock) >> 3))
+union cpu_time_count {
+	cputime_t cpu;
+	unsigned long long sched;
+};
+
+struct cpu_timer_list {
+	struct list_head entry;
+	union cpu_time_count expires, incr;
+	struct task_struct *task;
+	int firing;
+};
+
+#define CPUCLOCK_PID(clock)		((pid_t) ~((clock) >> 3))
 #define CPUCLOCK_PERTHREAD(clock) \
 	(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)
 #define CPUCLOCK_PID_MASK	7
@@ -30,15 +43,27 @@ struct k_itimer {
 	int it_overrun;			/* overrun on pending signal  */
 	int it_overrun_last;		/* overrun on last delivered signal */
 	int it_requeue_pending;         /* waiting to requeue this timer */
+#define REQUEUE_PENDING 1
 	int it_sigev_notify;		/* notify word of sigevent struct */
 	int it_sigev_signo;		/* signo word of sigevent struct */
 	sigval_t it_sigev_value;	/* value word of sigevent struct */
-	unsigned long it_incr;		/* interval specified in jiffies */
 	struct task_struct *it_process;	/* process to send signal to */
-	struct timer_list it_timer;
 	struct sigqueue *sigq;		/* signal queue entry. */
-	struct list_head abs_timer_entry; /* clock abs_timer_list */
-	struct timespec wall_to_prev;   /* wall_to_monotonic used when set */
+	union {
+		struct {
+			struct timer_list timer;
+			struct list_head abs_timer_entry; /* clock abs_timer_list */
+			struct timespec wall_to_prev;   /* wall_to_monotonic used when set */
+			unsigned long incr; /* interval in jiffies */
+		} real;
+		struct cpu_timer_list cpu;
+		struct {
+			unsigned int clock;
+			unsigned int node;
+			unsigned long incr;
+			unsigned long expires;
+		} mmtimer;
+	} it;
 };
 
 struct k_clock_abs {
@@ -57,6 +82,7 @@ struct k_clock {
 			  struct itimerspec * new_setting,
 			  struct itimerspec * old_setting);
 	int (*timer_del) (struct k_itimer * timr);
+#define TIMER_RETRY 1
 	void (*timer_get) (struct k_itimer * timr,
 			   struct itimerspec * cur_setting);
 };
@@ -82,10 +108,11 @@ struct now_struct {
 #define posix_bump_timer(timr, now)					\
          do {								\
               long delta, orun;						\
-	      delta = now.jiffies - (timr)->it_timer.expires;		\
+	      delta = now.jiffies - (timr)->it.real.timer.expires;	\
               if (delta >= 0) {						\
-	           orun = 1 + (delta / (timr)->it_incr);		\
-	          (timr)->it_timer.expires += orun * (timr)->it_incr;	\
+	           orun = 1 + (delta / (timr)->it.real.incr);		\
+	          (timr)->it.real.timer.expires +=			\
+			 orun * (timr)->it.real.incr;			\
                   (timr)->it_overrun += orun;				\
               }								\
             }while (0)
@@ -95,12 +122,16 @@ int posix_cpu_clock_get(clockid_t which_clock, struct timespec *);
 int posix_cpu_clock_set(clockid_t which_clock, const struct timespec *tp);
 int posix_cpu_timer_create(struct k_itimer *);
 int posix_cpu_nsleep(clockid_t, int, struct timespec *);
-#define posix_cpu_timer_create do_posix_clock_notimer_create
-#define posix_cpu_nsleep do_posix_clock_nonanosleep
 int posix_cpu_timer_set(struct k_itimer *, int,
 			struct itimerspec *, struct itimerspec *);
 int posix_cpu_timer_del(struct k_itimer *);
 void posix_cpu_timer_get(struct k_itimer *, struct itimerspec *);
 
+void posix_cpu_timer_schedule(struct k_itimer *);
+
+void run_posix_cpu_timers(struct task_struct *);
+void posix_cpu_timers_exit(struct task_struct *);
+void posix_cpu_timers_exit_group(struct task_struct *);
+
 
 #endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5fff51dc7c32..36a6174597f7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -338,6 +338,8 @@ struct signal_struct {
 	 * have no need to disable irqs.
 	 */
 	struct rlimit rlim[RLIM_NLIMITS];
+
+	struct list_head cpu_timers[3];
 };
 
 /*
@@ -612,6 +614,11 @@ struct task_struct {
 	struct timespec start_time;
 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
 	unsigned long min_flt, maj_flt;
+
+  	cputime_t it_prof_expires, it_virt_expires;
+	unsigned long long it_sched_expires;
+	struct list_head cpu_timers[3];
+
 /* process credentials */
 	uid_t uid,euid,suid,fsuid;
 	gid_t gid,egid,sgid,fsgid;