From: Richard Cochran Date: Tue, 1 Feb 2011 13:52:32 +0000 (+0000) Subject: posix-timers: Add support for fd based clocks X-Git-Tag: tegra-14.ER1-android-2.3~1766^2~13 X-Git-Url: https://nv-tegra.nvidia.com/r/gitweb?p=linux-2.6.git;a=commitdiff_plain;h=81e294cba2596f5f10848bbe19d98b344c2a2d5c 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 Signed-off-by: Thomas Gleixner Acked-by: John Stultz LKML-Reference: <20110201134420.062860200@linutronix.de> --- diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h index 79a1cea7f6e..88b9256169f 100644 --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -18,6 +18,17 @@ 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 are all set. + */ #define CPUCLOCK_PID(clock) ((pid_t) ~((clock) >> 3)) #define CPUCLOCK_PERTHREAD(clock) \ (((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0) @@ -29,6 +40,8 @@ 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)) diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 5a5a4f1c097..df629d853a8 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -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) { 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) return NULL;