From c5f8d99585d7b5b7e857fabf8aefd0174903a98c Mon Sep 17 00:00:00 2001 From: Hidetoshi Seto Date: Tue, 31 Mar 2009 16:56:03 +0900 Subject: posixtimers, sched: Fix posix clock monotonicity Impact: Regression fix (against clock_gettime() backwarding bug) This patch re-introduces a couple of functions, task_sched_runtime and thread_group_sched_runtime, which was once removed at the time of 2.6.28-rc1. These functions protect the sampling of thread/process clock with rq lock. This rq lock is required not to update rq->clock during the sampling. i.e. The clock_gettime() may return ((accounted runtime before update) + (delta after update)) that is less than what it should be. v2 -> v3: - Rename static helper function __task_delta_exec() to do_task_delta_exec() since -tip tree already has a __task_delta_exec() of different version. v1 -> v2: - Revises comments of function and patch description. - Add note about accuracy of thread group's runtime. Signed-off-by: Hidetoshi Seto Acked-by: Peter Zijlstra Cc: stable@kernel.org [2.6.28.x][2.6.29.x] LKML-Reference: <49D1CC93.4080401@jp.fujitsu.com> Signed-off-by: Ingo Molnar --- kernel/posix-cpu-timers.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'kernel/posix-cpu-timers.c') diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index fa07da94d7b..4318c308578 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -224,7 +224,7 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, cpu->cpu = virt_ticks(p); break; case CPUCLOCK_SCHED: - cpu->sched = p->se.sum_exec_runtime + task_delta_exec(p); + cpu->sched = task_sched_runtime(p); break; } return 0; @@ -240,18 +240,19 @@ static int cpu_clock_sample_group(const clockid_t which_clock, { struct task_cputime cputime; - thread_group_cputime(p, &cputime); switch (CPUCLOCK_WHICH(which_clock)) { default: return -EINVAL; case CPUCLOCK_PROF: + thread_group_cputime(p, &cputime); cpu->cpu = cputime_add(cputime.utime, cputime.stime); break; case CPUCLOCK_VIRT: + thread_group_cputime(p, &cputime); cpu->cpu = cputime.utime; break; case CPUCLOCK_SCHED: - cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p); + cpu->sched = thread_group_sched_runtime(p); break; } return 0; -- cgit v1.2.3 From 8f2e586567b1bad72dac7c3810fe9a2ef7117506 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 27 Mar 2009 01:06:10 +0100 Subject: posix-timers: fix RLIMIT_CPU && setitimer(CPUCLOCK_PROF) update_rlimit_cpu() tries to optimize out set_process_cpu_timer() in case when we already have CPUCLOCK_PROF timer which should expire first. But it uses cputime_lt() instead of cputime_gt(). Test case: int main(void) { struct itimerval it = { .it_value = { .tv_sec = 1000 }, }; assert(!setitimer(ITIMER_PROF, &it, NULL)); struct rlimit rl = { .rlim_cur = 1, .rlim_max = 1, }; assert(!setrlimit(RLIMIT_CPU, &rl)); for (;;) ; return 0; } Without this patch, the task is not killed as RLIMIT_CPU demands. Signed-off-by: Oleg Nesterov Acked-by: Peter Zijlstra Cc: Peter Lojkin Cc: Roland McGrath Cc: stable@kernel.org LKML-Reference: <20090327000610.GA10108@redhat.com> Signed-off-by: Ingo Molnar --- kernel/posix-cpu-timers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/posix-cpu-timers.c') diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 8e5d9a68b02..bb53185d8c7 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -18,7 +18,7 @@ void update_rlimit_cpu(unsigned long rlim_new) cputime = secs_to_cputime(rlim_new); if (cputime_eq(current->signal->it_prof_expires, cputime_zero) || - cputime_lt(current->signal->it_prof_expires, cputime)) { + cputime_gt(current->signal->it_prof_expires, cputime)) { spin_lock_irq(¤t->sighand->siglock); set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL); spin_unlock_irq(¤t->sighand->siglock); -- cgit v1.2.3 From 6e85c5ba73c07b990798087e9b858c065db2b234 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Wed, 29 Apr 2009 19:14:32 -0400 Subject: kernel/posix-cpu-timers.c: fix sparse warning Sparse reports the following in kernel/posix-cpu-timers.c: warning: symbol 'firing' shadows an earlier one Signed-off-by: H Hartley Sweeten Cc: Subrata Modak LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/posix-cpu-timers.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/posix-cpu-timers.c') diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index c9dcf98b446..bece7c0b67b 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1420,19 +1420,19 @@ void run_posix_cpu_timers(struct task_struct *tsk) * timer call will interfere. */ list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) { - int firing; + int cpu_firing; + spin_lock(&timer->it_lock); list_del_init(&timer->it.cpu.entry); - firing = timer->it.cpu.firing; + cpu_firing = timer->it.cpu.firing; timer->it.cpu.firing = 0; /* * The firing flag is -1 if we collided with a reset * of the timer, which already reported this * almost-firing as an overrun. So don't generate an event. */ - if (likely(firing >= 0)) { + if (likely(cpu_firing >= 0)) cpu_timer_fire(timer); - } spin_unlock(&timer->it_lock); } } -- cgit v1.2.3