X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;ds=sidebyside;f=kernel%2Fposix-cpu-timers.c;h=7c3e1e6dfb5b5eef84f61f6259e764703846d9fd;hb=c5c6b216cd905dfdab60444d44628387377b6f30;hp=13c0be232da17d3e9b479543b07136517518562a;hpb=e6a27dba1cf83d871b2dfcd64f04f12a67e3f4d5;p=linux-2.6.git diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 13c0be232..7c3e1e6df 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -6,7 +6,6 @@ #include #include #include -#include static int check_clock(const clockid_t which_clock) { @@ -88,6 +87,19 @@ static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock, return a; } +/* + * Divide and limit the result to res >= 1 + * + * This is necessary to prevent signal delivery starvation, when the result of + * the division would be rounded down to 0. + */ +static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div) +{ + cputime_t res = cputime_div(time, div); + + return max_t(cputime_t, res, 1); +} + /* * Update expiry time from increment, and increase overrun count, * given the current clock sample. @@ -484,8 +496,8 @@ static void process_timer_rebalance(struct task_struct *p, BUG(); break; case CPUCLOCK_PROF: - left = cputime_div(cputime_sub(expires.cpu, val.cpu), - nthreads); + left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu), + nthreads); do { if (likely(!(t->flags & PF_EXITING))) { ticks = cputime_add(prof_ticks(t), left); @@ -499,8 +511,8 @@ static void process_timer_rebalance(struct task_struct *p, } while (t != p); break; case CPUCLOCK_VIRT: - left = cputime_div(cputime_sub(expires.cpu, val.cpu), - nthreads); + left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu), + nthreads); do { if (likely(!(t->flags & PF_EXITING))) { ticks = cputime_add(virt_ticks(t), left); @@ -516,6 +528,7 @@ static void process_timer_rebalance(struct task_struct *p, case CPUCLOCK_SCHED: nsleft = expires.sched - val.sched; do_div(nsleft, nthreads); + nsleft = max_t(unsigned long long, nsleft, 1); do { if (likely(!(t->flags & PF_EXITING))) { ns = t->sched_time + nsleft; @@ -1160,12 +1173,13 @@ static void check_process_timers(struct task_struct *tsk, prof_left = cputime_sub(prof_expires, utime); prof_left = cputime_sub(prof_left, stime); - prof_left = cputime_div(prof_left, nthreads); + prof_left = cputime_div_non_zero(prof_left, nthreads); virt_left = cputime_sub(virt_expires, utime); - virt_left = cputime_div(virt_left, nthreads); + virt_left = cputime_div_non_zero(virt_left, nthreads); if (sched_expires) { sched_left = sched_expires - sched_time; do_div(sched_left, nthreads); + sched_left = max_t(unsigned long long, sched_left, 1); } else { sched_left = 0; } @@ -1394,24 +1408,12 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, } } -static long posix_cpu_clock_nanosleep_restart(struct restart_block *); - -int posix_cpu_nsleep(const clockid_t which_clock, int flags, - struct timespec *rqtp, struct timespec __user *rmtp) +static int do_cpu_nanosleep(const clockid_t which_clock, int flags, + struct timespec *rqtp, struct itimerspec *it) { - struct restart_block *restart_block = - ¤t_thread_info()->restart_block; struct k_itimer timer; int error; - /* - * Diagnose required errors first. - */ - if (CPUCLOCK_PERTHREAD(which_clock) && - (CPUCLOCK_PID(which_clock) == 0 || - CPUCLOCK_PID(which_clock) == current->pid)) - return -EINVAL; - /* * Set up a temporary timer and then wait for it to go off. */ @@ -1423,11 +1425,12 @@ int posix_cpu_nsleep(const clockid_t which_clock, int flags, timer.it_process = current; if (!error) { static struct itimerspec zero_it; - struct itimerspec it = { .it_value = *rqtp, - .it_interval = {} }; + + memset(it, 0, sizeof *it); + it->it_value = *rqtp; spin_lock_irq(&timer.it_lock); - error = posix_cpu_timer_set(&timer, flags, &it, NULL); + error = posix_cpu_timer_set(&timer, flags, it, NULL); if (error) { spin_unlock_irq(&timer.it_lock); return error; @@ -1455,49 +1458,89 @@ int posix_cpu_nsleep(const clockid_t which_clock, int flags, * We were interrupted by a signal. */ sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp); - posix_cpu_timer_set(&timer, 0, &zero_it, &it); + posix_cpu_timer_set(&timer, 0, &zero_it, it); spin_unlock_irq(&timer.it_lock); - if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) { + if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) { /* * It actually did fire already. */ return 0; } + error = -ERESTART_RESTARTBLOCK; + } + + return error; +} + +int posix_cpu_nsleep(const clockid_t which_clock, int flags, + struct timespec *rqtp, struct timespec __user *rmtp) +{ + struct restart_block *restart_block = + ¤t_thread_info()->restart_block; + struct itimerspec it; + int error; + + /* + * Diagnose required errors first. + */ + if (CPUCLOCK_PERTHREAD(which_clock) && + (CPUCLOCK_PID(which_clock) == 0 || + CPUCLOCK_PID(which_clock) == current->pid)) + return -EINVAL; + + error = do_cpu_nanosleep(which_clock, flags, rqtp, &it); + + if (error == -ERESTART_RESTARTBLOCK) { + + if (flags & TIMER_ABSTIME) + return -ERESTARTNOHAND; /* - * Report back to the user the time still remaining. - */ - if (rmtp != NULL && !(flags & TIMER_ABSTIME) && - copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) + * Report back to the user the time still remaining. + */ + if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) return -EFAULT; - restart_block->fn = posix_cpu_clock_nanosleep_restart; - /* Caller already set restart_block->arg1 */ + restart_block->fn = posix_cpu_nsleep_restart; restart_block->arg0 = which_clock; restart_block->arg1 = (unsigned long) rmtp; restart_block->arg2 = rqtp->tv_sec; restart_block->arg3 = rqtp->tv_nsec; - - error = -ERESTART_RESTARTBLOCK; } - return error; } -static long -posix_cpu_clock_nanosleep_restart(struct restart_block *restart_block) +long posix_cpu_nsleep_restart(struct restart_block *restart_block) { clockid_t which_clock = restart_block->arg0; struct timespec __user *rmtp; struct timespec t; + struct itimerspec it; + int error; rmtp = (struct timespec __user *) restart_block->arg1; t.tv_sec = restart_block->arg2; t.tv_nsec = restart_block->arg3; restart_block->fn = do_no_restart_syscall; - return posix_cpu_nsleep(which_clock, TIMER_ABSTIME, &t, rmtp); + error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it); + + if (error == -ERESTART_RESTARTBLOCK) { + /* + * Report back to the user the time still remaining. + */ + if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp)) + return -EFAULT; + + restart_block->fn = posix_cpu_nsleep_restart; + restart_block->arg0 = which_clock; + restart_block->arg1 = (unsigned long) rmtp; + restart_block->arg2 = t.tv_sec; + restart_block->arg3 = t.tv_nsec; + } + return error; + } @@ -1525,6 +1568,10 @@ static int process_cpu_nsleep(const clockid_t which_clock, int flags, { return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp); } +static long process_cpu_nsleep_restart(struct restart_block *restart_block) +{ + return -EINVAL; +} static int thread_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp) { @@ -1545,6 +1592,10 @@ static int thread_cpu_nsleep(const clockid_t which_clock, int flags, { return -EINVAL; } +static long thread_cpu_nsleep_restart(struct restart_block *restart_block) +{ + return -EINVAL; +} static __init int init_posix_cpu_timers(void) { @@ -1554,6 +1605,7 @@ static __init int init_posix_cpu_timers(void) .clock_set = do_posix_clock_nosettime, .timer_create = process_cpu_timer_create, .nsleep = process_cpu_nsleep, + .nsleep_restart = process_cpu_nsleep_restart, }; struct k_clock thread = { .clock_getres = thread_cpu_clock_getres, @@ -1561,6 +1613,7 @@ static __init int init_posix_cpu_timers(void) .clock_set = do_posix_clock_nosettime, .timer_create = thread_cpu_timer_create, .nsleep = thread_cpu_nsleep, + .nsleep_restart = thread_cpu_nsleep_restart, }; register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);