From b4d90e9f1ef1f19dcb2b1b1942c786c9c4225460 Mon Sep 17 00:00:00 2001 From: Pratyush Patel Date: Thu, 23 Jun 2016 20:50:37 +0200 Subject: hrtimer: Spelling fixes Fix a minor spelling error. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Richard Cochran Cc: Prarit Bhargava Signed-off-by: Pratyush Patel [jstultz: Added commit message] Signed-off-by: John Stultz --- kernel/time/hrtimer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 9ba7c820fc23..252ea4741592 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -703,7 +703,7 @@ static void clock_was_set_work(struct work_struct *work) static DECLARE_WORK(hrtimer_work, clock_was_set_work); /* - * Called from timekeeping and resume code to reprogramm the hrtimer + * Called from timekeeping and resume code to reprogram the hrtimer * interrupt device on all cpus. */ void clock_was_set_delayed(void) @@ -1241,7 +1241,7 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base, /* * Note: We clear the running state after enqueue_hrtimer and - * we do not reprogramm the event hardware. Happens either in + * we do not reprogram the event hardware. Happens either in * hrtimer_start_range_ns() or in hrtimer_interrupt() * * Note: Because we dropped the cpu_base->lock above, -- cgit v1.2.3 From 36374583f9084cdab4b5dcf5521a3ce55bebb9fa Mon Sep 17 00:00:00 2001 From: Kyle Walker Date: Sat, 6 Aug 2016 12:07:30 -0400 Subject: clocksource: Defer override invalidation unless clock is unstable Clocksources don't get the VALID_FOR_HRES flag until they have been checked by a watchdog. However, when using an override, the clocksource_select logic will clear the override value if the clocksource is not marked VALID_FOR_HRES during that inititial check. When using the boot arguments clocksource=, this selection can run before the watchdog, and can cause the override to be incorrectly cleared. To address this condition, the override_name is only invalidated for unstable clocksources. Otherwise, the override is left intact until after the watchdog has validated the clocksource as stable/unstable. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Richard Cochran Cc: Prarit Bhargava Cc: Martin Schwidefsky Signed-off-by: Kyle Walker Signed-off-by: John Stultz --- kernel/time/clocksource.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 6a5a310a1a53..7e4fad75acaa 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -600,9 +600,18 @@ static void __clocksource_select(bool skipcur) */ if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { /* Override clocksource cannot be used. */ - pr_warn("Override clocksource %s is not HRT compatible - cannot switch while in HRT/NOHZ mode\n", - cs->name); - override_name[0] = 0; + if (cs->flags & CLOCK_SOURCE_UNSTABLE) { + pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/NOHZ mode\n", + cs->name); + override_name[0] = 0; + } else { + /* + * The override cannot be currently verified. + * Deferring to let the watchdog check. + */ + pr_info("Override clocksource %s is not currently HRT compatible - deferring\n", + cs->name); + } } else /* Override clocksource can be used. */ best = cs; -- cgit v1.2.3 From 0bf43f15db857e83daf4134aa062c8b157a80ee0 Mon Sep 17 00:00:00 2001 From: Ruchi Kandoi Date: Thu, 11 Aug 2016 14:35:01 -0700 Subject: timekeeping: Prints the amounts of time spent during suspend In addition to keeping a histogram of suspend times, also print out the time spent in suspend to dmesg. This helps to keep track of suspend time while debugging using kernel logs. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Richard Cochran Cc: Prarit Bhargava Signed-off-by: Ruchi Kandoi [jstultz: Tweaked commit message] Signed-off-by: John Stultz --- kernel/time/timekeeping_debug.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/time/timekeeping_debug.c b/kernel/time/timekeeping_debug.c index 107310a6f36f..ca9fb800336b 100644 --- a/kernel/time/timekeeping_debug.c +++ b/kernel/time/timekeeping_debug.c @@ -75,5 +75,7 @@ void tk_debug_account_sleep_time(struct timespec64 *t) int bin = min(fls(t->tv_sec), NUM_BINS-1); sleep_time_bin[bin]++; + pr_info("Suspended for %lld.%03lu seconds\n", (s64)t->tv_sec, + t->tv_nsec / NSEC_PER_MSEC); } -- cgit v1.2.3 From 469e857f374640f6164913835ce30d0736b40a60 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Fri, 12 Aug 2016 20:14:09 +0200 Subject: time: Avoid undefined behaviour in timespec64_add_safe() I ran into this: ================================================================================ UBSAN: Undefined behaviour in kernel/time/time.c:783:2 signed integer overflow: 5273 + 9223372036854771711 cannot be represented in type 'long int' CPU: 0 PID: 17363 Comm: trinity-c0 Not tainted 4.8.0-rc1+ #88 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 0000000000000000 ffff88011457f8f0 ffffffff82344f50 0000000041b58ab3 ffffffff84f98080 ffffffff82344ea4 ffff88011457f918 ffff88011457f8c8 ffff88011457f8e0 7fffffffffffefff ffff88011457f6d8 dffffc0000000000 Call Trace: [] dump_stack+0xac/0xfc [] ? _atomic_dec_and_lock+0xc4/0xc4 [] ubsan_epilogue+0xd/0x8a [] handle_overflow+0x202/0x23d [] ? val_to_string.constprop.6+0x11e/0x11e [] ? debug_smp_processor_id+0x17/0x20 [] ? __sigqueue_free.part.13+0x51/0x70 [] ? rcu_is_watching+0x110/0x110 [] __ubsan_handle_add_overflow+0xe/0x10 [] timespec64_add_safe+0x298/0x340 [] ? timespec_add_safe+0x330/0x330 [] ? wait_noreap_copyout+0x1d0/0x1d0 [] poll_select_set_timeout+0xf8/0x170 [] ? poll_schedule_timeout+0x2b0/0x2b0 [] ? __might_sleep+0x5b/0x260 [] __sys_recvmmsg+0x107/0x790 [] ? SyS_recvmsg+0x20/0x20 [] ? hrtimer_start_range_ns+0x3b8/0x1380 [] ? _raw_spin_unlock_irqrestore+0x3b/0x60 [] ? do_setitimer+0x39a/0x8e0 [] ? __might_sleep+0x5b/0x260 [] ? __sys_recvmmsg+0x790/0x790 [] SyS_recvmmsg+0xd9/0x160 [] ? __sys_recvmmsg+0x790/0x790 [] ? __this_cpu_preempt_check+0x13/0x20 [] ? __context_tracking_exit.part.3+0x30/0x1b0 [] ? __sys_recvmmsg+0x790/0x790 [] do_syscall_64+0x1b3/0x4b0 [] entry_SYSCALL64_slow_path+0x25/0x25 ================================================================================ Line 783 is this: 783 set_normalized_timespec64(&res, lhs.tv_sec + rhs.tv_sec, 784 lhs.tv_nsec + rhs.tv_nsec); In other words, since lhs.tv_sec and rhs.tv_sec are both time64_t, this is a signed addition which will cause undefined behaviour on overflow. Note that this is not currently a huge concern since the kernel should be built with -fno-strict-overflow by default, but could be a problem in the future, a problem with older compilers, or other compilers than gcc. The easiest way to avoid the overflow is to cast one of the arguments to unsigned (so the addition will be done using unsigned arithmetic). Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Richard Cochran Cc: Prarit Bhargava Signed-off-by: Vegard Nossum Signed-off-by: John Stultz --- include/linux/time64.h | 1 + kernel/time/time.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/include/linux/time64.h b/include/linux/time64.h index 7e5d2fa9ac46..980c71b3001a 100644 --- a/include/linux/time64.h +++ b/include/linux/time64.h @@ -5,6 +5,7 @@ #include typedef __s64 time64_t; +typedef __u64 timeu64_t; /* * This wants to go into uapi/linux/time.h once we agreed about the diff --git a/kernel/time/time.c b/kernel/time/time.c index 667b9335f5d6..bd62fb8e8e77 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -780,7 +780,7 @@ struct timespec64 timespec64_add_safe(const struct timespec64 lhs, { struct timespec64 res; - set_normalized_timespec64(&res, lhs.tv_sec + rhs.tv_sec, + set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec, lhs.tv_nsec + rhs.tv_nsec); if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) { -- cgit v1.2.3 From 979515c5645830465739254abc1b1648ada41518 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Sat, 13 Aug 2016 01:37:04 +0200 Subject: time: Avoid undefined behaviour in ktime_add_safe() I ran into this: ================================================================================ UBSAN: Undefined behaviour in kernel/time/hrtimer.c:310:16 signed integer overflow: 9223372036854775807 + 50000 cannot be represented in type 'long long int' CPU: 2 PID: 4798 Comm: trinity-c2 Not tainted 4.8.0-rc1+ #91 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 0000000000000000 ffff88010ce6fb88 ffffffff82344740 0000000041b58ab3 ffffffff84f97a20 ffffffff82344694 ffff88010ce6fbb0 ffff88010ce6fb60 000000000000c350 ffff88010ce6f968 dffffc0000000000 ffffffff857bc320 Call Trace: [] dump_stack+0xac/0xfc [] ? _atomic_dec_and_lock+0xc4/0xc4 [] ubsan_epilogue+0xd/0x8a [] handle_overflow+0x202/0x23d [] ? val_to_string.constprop.6+0x11e/0x11e [] ? timerqueue_add+0x151/0x410 [] ? hrtimer_start_range_ns+0x3b8/0x1380 [] ? memset+0x31/0x40 [] __ubsan_handle_add_overflow+0xe/0x10 [] hrtimer_nanosleep+0x5d9/0x790 [] ? hrtimer_init_sleeper+0x80/0x80 [] ? __might_sleep+0x5b/0x260 [] common_nsleep+0x20/0x30 [] SyS_clock_nanosleep+0x197/0x210 [] ? SyS_clock_getres+0x150/0x150 [] ? __this_cpu_preempt_check+0x13/0x20 [] ? __context_tracking_exit.part.3+0x30/0x1b0 [] ? SyS_clock_getres+0x150/0x150 [] do_syscall_64+0x1b3/0x4b0 [] entry_SYSCALL64_slow_path+0x25/0x25 ================================================================================ Add a new ktime_add_unsafe() helper which doesn't check for overflow, but doesn't throw a UBSAN warning when it does overflow either. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Richard Cochran Cc: Prarit Bhargava Signed-off-by: Vegard Nossum Signed-off-by: John Stultz --- include/linux/ktime.h | 7 +++++++ kernel/time/hrtimer.c | 2 +- 2 files changed, 8 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/include/linux/ktime.h b/include/linux/ktime.h index 2b6a204bd8d4..3ffc69ebe967 100644 --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -63,6 +63,13 @@ static inline ktime_t ktime_set(const s64 secs, const unsigned long nsecs) #define ktime_add(lhs, rhs) \ ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; }) +/* + * Same as ktime_add(), but avoids undefined behaviour on overflow; however, + * this means that you must check the result for overflow yourself. + */ +#define ktime_add_unsafe(lhs, rhs) \ + ({ (ktime_t){ .tv64 = (u64) (lhs).tv64 + (rhs).tv64 }; }) + /* * Add a ktime_t variable and a scalar nanosecond value. * res = kt + nsval: diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 252ea4741592..bb5ec425dfe0 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -307,7 +307,7 @@ EXPORT_SYMBOL_GPL(__ktime_divns); */ ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs) { - ktime_t res = ktime_add(lhs, rhs); + ktime_t res = ktime_add_unsafe(lhs, rhs); /* * We use KTIME_SEC_MAX here, the maximum timeout which we can -- cgit v1.2.3 From 57ccdf449f962ab5fc8cbf26479402f13bdb8be7 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Wed, 7 Sep 2016 18:51:13 +0800 Subject: tick/nohz: Prevent stopping the tick on an offline CPU can_stop_full_tick() has no check for offline cpus. So it allows to stop the tick on an offline cpu from the interrupt return path, which is wrong and subsequently makes irq_work_needs_cpu() warn about being called for an offline cpu. Commit f7ea0fd639c2c4 ("tick: Don't invoke tick_nohz_stop_sched_tick() if the cpu is offline") added prevention for can_stop_idle_tick(), but forgot to do the same in can_stop_full_tick(). Add it. [ tglx: Massaged changelog ] Signed-off-by: Wanpeng Li Cc: Peter Zijlstra Cc: Frederic Weisbecker Link: http://lkml.kernel.org/r/1473245473-4463-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Thomas Gleixner --- kernel/time/tick-sched.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 2ec7c00228f3..3bcb61b52f6c 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -186,10 +186,13 @@ static bool check_tick_dependency(atomic_t *dep) return false; } -static bool can_stop_full_tick(struct tick_sched *ts) +static bool can_stop_full_tick(int cpu, struct tick_sched *ts) { WARN_ON_ONCE(!irqs_disabled()); + if (unlikely(!cpu_online(cpu))) + return false; + if (check_tick_dependency(&tick_dep_mask)) return false; @@ -843,7 +846,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts) if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) return; - if (can_stop_full_tick(ts)) + if (can_stop_full_tick(cpu, ts)) tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); else if (ts->tick_stopped) tick_nohz_restart_sched_tick(ts, ktime_get()); -- cgit v1.2.3