Date:	Thu, 16 Dec 2010 16:43:55 +0100
From:	Richard Cochran <richardcochran@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-api@...r.kernel.org, netdev@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Christoph Lameter <cl@...ux.com>,
	David Miller <davem@...emloft.net>,
	John Stultz <johnstul@...ibm.com>,
	Krzysztof Halasa <khc@...waw.pl>,
	Peter Zijlstra <peterz@...radead.org>,
	Rodolfo Giometti <giometti@...ux.it>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH V7 4/8] posix clocks: hook dynamic clocks into system calls

This patch lets the various posix clock and timer system calls use
dynamic posix clocks, as well as the traditional static clocks.

For the performance critical calls (eg clock_gettime) the code path
from the traditional static clocks is preserved.

The following system calls are affected:

   - clock_adjtime (brand new syscall)
   - clock_gettime
   - clock_getres
   - clock_settime
   - timer_create
   - timer_delete
   - timer_gettime
   - timer_settime

Signed-off-by: Richard Cochran <richard.cochran@...cron.at>
---
 include/linux/posix-clock.h  |   25 +++++++
 include/linux/posix-timers.h |   28 +++++++-
 include/linux/time.h         |    2 +
 kernel/posix-timers.c        |  122 +++++++++++++++++++++++++++-----
 kernel/time/posix-clock.c    |  159 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 316 insertions(+), 20 deletions(-)

diff --git a/include/linux/posix-clock.h b/include/linux/posix-clock.h
index 1ce7fb7..7ea94f5 100644
--- a/include/linux/posix-clock.h
+++ b/include/linux/posix-clock.h
@@ -108,4 +108,29 @@ struct posix_clock *posix_clock_create(struct posix_clock_operations *cops,
  */
 void posix_clock_destroy(struct posix_clock *clk);
 
+/**
+ * clockid_to_posix_clock() - obtain clock device pointer from a clock id
+ * @id: user space clock id
+ *
+ * Returns a pointer to the clock device, or NULL if the id is not a
+ * dynamic clock id.
+ */
+struct posix_clock *clockid_to_posix_clock(clockid_t id);
+
+/*
+ * The following functions are only to be called from posix-timers.c
+ */
+int pc_clock_adjtime(struct posix_clock *clk, struct timex *tx);
+int pc_clock_gettime(struct posix_clock *clk, struct timespec *ts);
+int pc_clock_getres(struct posix_clock *clk, struct timespec *ts);
+int pc_clock_settime(struct posix_clock *clk, const struct timespec *ts);
+
+int pc_timer_create(struct posix_clock *clk, struct k_itimer *kit);
+int pc_timer_delete(struct posix_clock *clk, struct k_itimer *kit);
+
+void pc_timer_gettime(struct posix_clock *clk, struct k_itimer *kit,
+		      struct itimerspec *ts);
+int pc_timer_settime(struct posix_clock *clk, struct k_itimer *kit,
+		     int flags, struct itimerspec *ts, struct itimerspec *old);
+
 #endif
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index b05d9b8..62ae296 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -18,10 +18,22 @@ struct cpu_timer_list {
 	int firing;
 };
 
+/* Bit fields within a clockid:
+ *
+ * The most significant 29 bits hold either a pid or a file descriptor.
+ *
+ * Bit 2 indicates whether a cpu clock refers to a thread or a process.
+ *
+ * Bits 1 and 0 give the type: PROF=0, VIRT=1, SCHED=2, or FD=3.
+ *
+ * A clockid is invalid if bits 2, 1, and 0 all set (see also CLOCK_INVALID
+ * in include/linux/time.h)
+ */
+
 #define CPUCLOCK_PID(clock)		((pid_t) ~((clock) >> 3))
 #define CPUCLOCK_PERTHREAD(clock) \
 	(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)
-#define CPUCLOCK_PID_MASK	7
+
 #define CPUCLOCK_PERTHREAD_MASK	4
 #define CPUCLOCK_WHICH(clock)	((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
 #define CPUCLOCK_CLOCK_MASK	3
@@ -29,12 +41,26 @@ struct cpu_timer_list {
 #define CPUCLOCK_VIRT		1
 #define CPUCLOCK_SCHED		2
 #define CPUCLOCK_MAX		3
+#define CLOCKFD			CPUCLOCK_MAX
+#define CLOCKFD_MASK		(CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)
 
 #define MAKE_PROCESS_CPUCLOCK(pid, clock) \
 	((~(clockid_t) (pid) << 3) | (clockid_t) (clock))
 #define MAKE_THREAD_CPUCLOCK(tid, clock) \
 	MAKE_PROCESS_CPUCLOCK((tid), (clock) | CPUCLOCK_PERTHREAD_MASK)
 
+#define FD_TO_CLOCKID(fd)  ((clockid_t) (fd << 3) | CLOCKFD)
+#define CLOCKID_TO_FD(clk) (((unsigned int) clk) >> 3)
+
+static inline bool clock_is_static(const clockid_t id)
+{
+	if (0 == (id & ~CLOCKFD_MASK))
+		return true;
+	if (CLOCKFD == (id & CLOCKFD_MASK))
+		return false;
+	return true;
+}
+
 /* POSIX.1b interval timer structure. */
 struct k_itimer {
 	struct list_head list;		/* free/ allocate list */
diff --git a/include/linux/time.h b/include/linux/time.h
index 9f15ac7..914c48d 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -299,6 +299,8 @@ struct itimerval {
 #define CLOCKS_MASK			(CLOCK_REALTIME | CLOCK_MONOTONIC)
 #define CLOCKS_MONO			CLOCK_MONOTONIC
 
+#define CLOCK_INVALID			-1
+
 /*
  * The various flags for setting POSIX.1b interval timers:
  */
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 502bde4..cca3bd5 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -41,6 +41,7 @@
 #include <linux/init.h>
 #include <linux/compiler.h>
 #include <linux/idr.h>
+#include <linux/posix-clock.h>
 #include <linux/posix-timers.h>
 #include <linux/syscalls.h>
 #include <linux/wait.h>
@@ -532,12 +533,15 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 		struct sigevent __user *, timer_event_spec,
 		timer_t __user *, created_timer_id)
 {
+	struct posix_clock *clk_dev;
 	struct k_itimer *new_timer;
 	int error, new_timer_id;
 	sigevent_t event;
 	int it_id_set = IT_ID_NOT_SET;
 
-	if (invalid_clockid(which_clock))
+	clk_dev = clockid_to_posix_clock(which_clock);
+
+	if (!clk_dev && invalid_clockid(which_clock))
 		return -EINVAL;
 
 	new_timer = alloc_posix_timer();
@@ -600,7 +604,11 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 		goto out;
 	}
 
-	error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
+	if (unlikely(clk_dev))
+		error = pc_timer_create(clk_dev, new_timer);
+	else {
+		error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
+	}
 	if (error)
 		goto out;
 
@@ -712,6 +720,7 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
 SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
 		struct itimerspec __user *, setting)
 {
+	struct posix_clock *clk_dev;
 	struct k_itimer *timr;
 	struct itimerspec cur_setting;
 	unsigned long flags;
@@ -720,7 +729,15 @@ SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
 	if (!timr)
 		return -EINVAL;
 
-	CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));
+	if (likely(clock_is_static(timr->it_clock))) {
+
+		CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));
+
+	} else {
+		clk_dev = clockid_to_posix_clock(timr->it_clock);
+		if (clk_dev)
+			pc_timer_gettime(clk_dev, timr, &cur_setting);
+	}
 
 	unlock_timer(timr, flags);
 
@@ -811,6 +828,7 @@ SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
 		const struct itimerspec __user *, new_setting,
 		struct itimerspec __user *, old_setting)
 {
+	struct posix_clock *clk_dev;
 	struct k_itimer *timr;
 	struct itimerspec new_spec, old_spec;
 	int error = 0;
@@ -831,8 +849,19 @@ retry:
 	if (!timr)
 		return -EINVAL;
 
-	error = CLOCK_DISPATCH(timr->it_clock, timer_set,
-			       (timr, flags, &new_spec, rtn));
+	if (likely(clock_is_static(timr->it_clock))) {
+
+		error = CLOCK_DISPATCH(timr->it_clock, timer_set,
+				       (timr, flags, &new_spec, rtn));
+
+	} else {
+		clk_dev = clockid_to_posix_clock(timr->it_clock);
+		if (clk_dev)
+			error = pc_timer_settime(clk_dev, timr,
+						 flags, &new_spec, rtn);
+		else
+			error = -EINVAL;
+	}
 
 	unlock_timer(timr, flag);
 	if (error == TIMER_RETRY) {
@@ -858,6 +887,13 @@ static inline int common_timer_del(struct k_itimer *timer)
 
 static inline int timer_delete_hook(struct k_itimer *timer)
 {
+	struct posix_clock *clk_dev;
+
+	clk_dev = clockid_to_posix_clock(timer->it_clock);
+
+	if (clk_dev)
+		return pc_timer_delete(clk_dev, timer);
+
 	return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
 }
 
@@ -957,26 +993,51 @@ EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep);
 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 		const struct timespec __user *, tp)
 {
+	struct posix_clock *clk_dev = NULL;
 	struct timespec new_tp;
 
-	if (invalid_clockid(which_clock))
-		return -EINVAL;
+	if (likely(clock_is_static(which_clock))) {
+
+		if (invalid_clockid(which_clock))
+			return -EINVAL;
+	} else {
+		clk_dev = clockid_to_posix_clock(which_clock);
+		if (!clk_dev)
+			return -EINVAL;
+	}
+
 	if (copy_from_user(&new_tp, tp, sizeof (*tp)))
 		return -EFAULT;
 
+	if (unlikely(clk_dev))
+		return pc_clock_settime(clk_dev, &new_tp);
+
 	return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
 }
 
 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
-		struct timespec __user *,tp)
+		struct timespec __user *, tp)
 {
+	struct posix_clock *clk_dev;
 	struct timespec kernel_tp;
 	int error;
 
-	if (invalid_clockid(which_clock))
-		return -EINVAL;
-	error = CLOCK_DISPATCH(which_clock, clock_get,
-			       (which_clock, &kernel_tp));
+	if (likely(clock_is_static(which_clock))) {
+
+		if (invalid_clockid(which_clock))
+			return -EINVAL;
+
+		error = CLOCK_DISPATCH(which_clock, clock_get,
+				       (which_clock, &kernel_tp));
+	} else {
+		clk_dev = clockid_to_posix_clock(which_clock);
+
+		if (!clk_dev)
+			return -EINVAL;
+
+		error = pc_clock_gettime(clk_dev, &kernel_tp);
+	}
+
 	if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
 		error = -EFAULT;
 
@@ -987,16 +1048,28 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 		struct timex __user *, utx)
 {
+	struct posix_clock *clk_dev;
 	struct timex ktx;
 	int err;
 
 	if (copy_from_user(&ktx, utx, sizeof(ktx)))
 		return -EFAULT;
 
-	if (invalid_clockid(which_clock))
-		return -EINVAL;
+	if (likely(clock_is_static(which_clock))) {
 
-	err = CLOCK_DISPATCH(which_clock, clock_adj, (which_clock, &ktx));
+		if (invalid_clockid(which_clock))
+			return -EINVAL;
+
+		err = CLOCK_DISPATCH(which_clock, clock_adj,
+				     (which_clock, &ktx));
+	} else {
+		clk_dev = clockid_to_posix_clock(which_clock);
+
+		if (!clk_dev)
+			return -EINVAL;
+
+		err = pc_clock_adjtime(clk_dev, &ktx);
+	}
 
 	if (copy_to_user(utx, &ktx, sizeof(ktx)))
 		return -EFAULT;
@@ -1007,14 +1080,25 @@ SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 		struct timespec __user *, tp)
 {
+	struct posix_clock *clk_dev;
 	struct timespec rtn_tp;
 	int error;
 
-	if (invalid_clockid(which_clock))
-		return -EINVAL;
+	if (likely(clock_is_static(which_clock))) {
 
-	error = CLOCK_DISPATCH(which_clock, clock_getres,
-			       (which_clock, &rtn_tp));
+		if (invalid_clockid(which_clock))
+			return -EINVAL;
+
+		error = CLOCK_DISPATCH(which_clock, clock_getres,
+				       (which_clock, &rtn_tp));
+	} else {
+		clk_dev = clockid_to_posix_clock(which_clock);
+
+		if (!clk_dev)
+			return -EINVAL;
+
+		error = pc_clock_getres(clk_dev, &rtn_tp);
+	}
 
 	if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
 		error = -EFAULT;
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index e5924c9..a707c10 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -19,9 +19,12 @@
  */
 #include <linux/cdev.h>
 #include <linux/device.h>
+#include <linux/file.h>
 #include <linux/mutex.h>
 #include <linux/posix-clock.h>
 #include <linux/slab.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
 
 #define MAX_CLKDEV BITS_PER_LONG
 static DECLARE_BITMAP(clocks_map, MAX_CLKDEV);
@@ -215,3 +218,159 @@ void posix_clock_destroy(struct posix_clock *clk)
 	kref_put(&clk->kref, delete_clock);
 }
 EXPORT_SYMBOL_GPL(posix_clock_destroy);
+
+struct posix_clock *clockid_to_posix_clock(const clockid_t id)
+{
+	struct posix_clock *clk = NULL;
+	struct file *fp;
+
+	if (clock_is_static(id))
+		return NULL;
+
+	fp = fget(CLOCKID_TO_FD(id));
+	if (!fp)
+		return NULL;
+
+	if (fp->f_op->open == posix_clock_open)
+		clk = fp->private_data;
+
+	fput(fp);
+	return clk;
+}
+
+int pc_clock_adjtime(struct posix_clock *clk, struct timex *tx)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->clock_adjtime)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->clock_adjtime(clk->priv, tx);
+
+	mutex_unlock(&clk->mux);
+	return err;
+}
+
+int pc_clock_gettime(struct posix_clock *clk, struct timespec *ts)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->clock_gettime)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->clock_gettime(clk->priv, ts);
+
+	mutex_unlock(&clk->mux);
+	return err;
+}
+
+int pc_clock_getres(struct posix_clock *clk, struct timespec *ts)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->clock_getres)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->clock_getres(clk->priv, ts);
+
+	mutex_unlock(&clk->mux);
+	return err;
+}
+
+int pc_clock_settime(struct posix_clock *clk, const struct timespec *ts)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->clock_settime)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->clock_settime(clk->priv, ts);
+
+	mutex_unlock(&clk->mux);
+	return err;
+}
+
+int pc_timer_create(struct posix_clock *clk, struct k_itimer *kit)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->timer_create)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->timer_create(clk->priv, kit);
+
+	mutex_unlock(&clk->mux);
+	return err;
+}
+
+int pc_timer_delete(struct posix_clock *clk, struct k_itimer *kit)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->timer_delete)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->timer_delete(clk->priv, kit);
+
+	mutex_unlock(&clk->mux);
+
+	return err;
+}
+
+void pc_timer_gettime(struct posix_clock *clk, struct k_itimer *kit,
+		      struct itimerspec *ts)
+{
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		goto out;
+	else if (!clk->ops->timer_gettime)
+		goto out;
+	else
+		clk->ops->timer_gettime(clk->priv, kit, ts);
+out:
+	mutex_unlock(&clk->mux);
+}
+
+int pc_timer_settime(struct posix_clock *clk, struct k_itimer *kit,
+		     int flags, struct itimerspec *ts, struct itimerspec *old)
+{
+	int err;
+
+	mutex_lock(&clk->mux);
+
+	if (clk->zombie)
+		err = -ENODEV;
+	else if (!clk->ops->timer_settime)
+		err = -EOPNOTSUPP;
+	else
+		err = clk->ops->timer_settime(clk->priv, kit, flags, ts, old);
+
+	mutex_unlock(&clk->mux);
+
+	return err;
+}
-- 
1.7.0.4

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