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Commit 81e294cb authored by Richard Cochran's avatar Richard Cochran Committed by Thomas Gleixner
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posix-timers: Add support for fd based clocks 



Extend the negative clockids which are currently used by posix cpu
timers to encode the PID with a file descriptor based type which
encodes the fd in the upper bits.

Originally-from: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <20110201134420.062860200@linutronix.de>
parent ce26efde

include/linux/posix-timers.h

+13 −0
Original line number Original line Diff line number Diff line
@@ -18,6 +18,17 @@ struct cpu_timer_list { 
	int firing;

	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 are all set.

 */

#define CPUCLOCK_PID(clock)		((pid_t) ~((clock) >> 3))

#define CPUCLOCK_PID(clock)		((pid_t) ~((clock) >> 3))

#define CPUCLOCK_PERTHREAD(clock) \

#define CPUCLOCK_PERTHREAD(clock) \

	(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)

	(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)
@@ -29,6 +40,8 @@ struct cpu_timer_list { 
#define CPUCLOCK_VIRT		1

#define CPUCLOCK_VIRT		1

#define CPUCLOCK_SCHED		2

#define CPUCLOCK_SCHED		2

#define CPUCLOCK_MAX		3

#define CPUCLOCK_MAX		3

#define CLOCKFD			CPUCLOCK_MAX

#define CLOCKFD_MASK		(CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)





#define MAKE_PROCESS_CPUCLOCK(pid, clock) \

#define MAKE_PROCESS_CPUCLOCK(pid, clock) \

	((~(clockid_t) (pid) << 3) | (clockid_t) (clock))

	((~(clockid_t) (pid) << 3) | (clockid_t) (clock))

kernel/posix-timers.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -488,7 +488,7 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set) 
static struct k_clock *clockid_to_kclock(const clockid_t id)

static struct k_clock *clockid_to_kclock(const clockid_t id)

{

{

	if (id < 0)

	if (id < 0)

		return &clock_posix_cpu;

		return (id & CLOCKFD_MASK) == CLOCKFD ? NULL : &clock_posix_cpu;





	if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)

	if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)

		return NULL;

		return NULL;