Commit c748fc3b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'timers-urgent-2024-04-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull timer fixes from Ingo Molnar:

 - Address a (valid) W=1 build warning

 - Fix timer self-tests

 - Annotate a KCSAN warning wrt. accesses to the tick_do_timer_cpu
   global variable

 - Address a !CONFIG_BUG build warning

* tag 'timers-urgent-2024-04-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests: kselftest: Fix build failure with NOLIBC
  selftests: timers: Fix abs() warning in posix_timers test
  selftests: kselftest: Mark functions that unconditionally call exit() as __noreturn
  selftests: timers: Fix posix_timers ksft_print_msg() warning
  selftests: timers: Fix valid-adjtimex signed left-shift undefined behavior
  bug: Fix no-return-statement warning with !CONFIG_BUG
  timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu
  selftests/timers/posix_timers: Reimplement check_timer_distribution()
  irqflags: Explicitly ignore lockdep_hrtimer_exit() argument
parents a1505c47 16767502

include/asm-generic/bug.h

+4 −1
Original line number Diff line number Diff line
@@ -156,7 +156,10 @@ extern __printf(1, 2) void __warn_printk(const char *fmt, ...); 


#else /* !CONFIG_BUG */

#ifndef HAVE_ARCH_BUG

#define BUG() do {} while (1)

#define BUG() do {		\

	do {} while (1);	\

	unreachable();		\

} while (0)

#endif



#ifndef HAVE_ARCH_BUG_ON

include/linux/irqflags.h

+1 −1
Original line number Diff line number Diff line
@@ -114,7 +114,7 @@ do { \ 
# define lockdep_softirq_enter()		do { } while (0)

# define lockdep_softirq_exit()			do { } while (0)

# define lockdep_hrtimer_enter(__hrtimer)	false

# define lockdep_hrtimer_exit(__context)	do { } while (0)

# define lockdep_hrtimer_exit(__context)	do { (void)(__context); } while (0)

# define lockdep_posixtimer_enter()		do { } while (0)

# define lockdep_posixtimer_exit()		do { } while (0)

# define lockdep_irq_work_enter(__work)		do { } while (0)

kernel/time/tick-common.c

+9 −8
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar

 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner

 */

#include <linux/compiler.h>

#include <linux/cpu.h>

#include <linux/err.h>

#include <linux/hrtimer.h>
@@ -84,7 +85,7 @@ int tick_is_oneshot_available(void) 
 */

static void tick_periodic(int cpu)

{

	if (tick_do_timer_cpu == cpu) {

	if (READ_ONCE(tick_do_timer_cpu) == cpu) {

		raw_spin_lock(&jiffies_lock);

		write_seqcount_begin(&jiffies_seq);
@@ -215,8 +216,8 @@ static void tick_setup_device(struct tick_device *td, 
		 * If no cpu took the do_timer update, assign it to

		 * this cpu:

		 */

		if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {

			tick_do_timer_cpu = cpu;

		if (READ_ONCE(tick_do_timer_cpu) == TICK_DO_TIMER_BOOT) {

			WRITE_ONCE(tick_do_timer_cpu, cpu);

			tick_next_period = ktime_get();

#ifdef CONFIG_NO_HZ_FULL

			/*
@@ -232,7 +233,7 @@ static void tick_setup_device(struct tick_device *td, 
						!tick_nohz_full_cpu(cpu)) {

			tick_take_do_timer_from_boot();

			tick_do_timer_boot_cpu = -1;

			WARN_ON(tick_do_timer_cpu != cpu);

			WARN_ON(READ_ONCE(tick_do_timer_cpu) != cpu);

#endif

		}
@@ -406,10 +407,10 @@ void tick_assert_timekeeping_handover(void) 
int tick_cpu_dying(unsigned int dying_cpu)

{

	/*

	 * If the current CPU is the timekeeper, it's the only one that

	 * can safely hand over its duty. Also all online CPUs are in

	 * stop machine, guaranteed not to be idle, therefore it's safe

	 * to pick any online successor.

	 * If the current CPU is the timekeeper, it's the only one that can

	 * safely hand over its duty. Also all online CPUs are in stop

	 * machine, guaranteed not to be idle, therefore there is no

	 * concurrency and it's safe to pick any online successor.

	 */

	if (tick_do_timer_cpu == dying_cpu)

		tick_do_timer_cpu = cpumask_first(cpu_online_mask);

kernel/time/tick-sched.c

+22 −14
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
 *

 *  Started by: Thomas Gleixner and Ingo Molnar

 */

#include <linux/compiler.h>

#include <linux/cpu.h>

#include <linux/err.h>

#include <linux/hrtimer.h>
@@ -204,7 +205,7 @@ static inline void tick_sched_flag_clear(struct tick_sched *ts, 


static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now)

{

	int cpu = smp_processor_id();

	int tick_cpu, cpu = smp_processor_id();



	/*

	 * Check if the do_timer duty was dropped. We don't care about
@@ -216,16 +217,18 @@ static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) 
	 * If nohz_full is enabled, this should not happen because the

	 * 'tick_do_timer_cpu' CPU never relinquishes.

	 */

	if (IS_ENABLED(CONFIG_NO_HZ_COMMON) &&

	    unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) {

	tick_cpu = READ_ONCE(tick_do_timer_cpu);



	if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && unlikely(tick_cpu == TICK_DO_TIMER_NONE)) {

#ifdef CONFIG_NO_HZ_FULL

		WARN_ON_ONCE(tick_nohz_full_running);

#endif

		tick_do_timer_cpu = cpu;

		WRITE_ONCE(tick_do_timer_cpu, cpu);

		tick_cpu = cpu;

	}



	/* Check if jiffies need an update */

	if (tick_do_timer_cpu == cpu)

	if (tick_cpu == cpu)

		tick_do_update_jiffies64(now);



	/*
@@ -610,7 +613,7 @@ bool tick_nohz_cpu_hotpluggable(unsigned int cpu) 
	 * timers, workqueues, timekeeping, ...) on behalf of full dynticks

	 * CPUs. It must remain online when nohz full is enabled.

	 */

	if (tick_nohz_full_running && tick_do_timer_cpu == cpu)

	if (tick_nohz_full_running && READ_ONCE(tick_do_timer_cpu) == cpu)

		return false;

	return true;

}
@@ -891,6 +894,7 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu) 
{

	u64 basemono, next_tick, delta, expires;

	unsigned long basejiff;

	int tick_cpu;



	basemono = get_jiffies_update(&basejiff);

	ts->last_jiffies = basejiff;
@@ -947,9 +951,9 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu) 
	 * Otherwise we can sleep as long as we want.

	 */

	delta = timekeeping_max_deferment();

	if (cpu != tick_do_timer_cpu &&

	    (tick_do_timer_cpu != TICK_DO_TIMER_NONE ||

	     !tick_sched_flag_test(ts, TS_FLAG_DO_TIMER_LAST)))

	tick_cpu = READ_ONCE(tick_do_timer_cpu);

	if (tick_cpu != cpu &&

	    (tick_cpu != TICK_DO_TIMER_NONE || !tick_sched_flag_test(ts, TS_FLAG_DO_TIMER_LAST)))

		delta = KTIME_MAX;



	/* Calculate the next expiry time */
@@ -970,6 +974,7 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) 
	unsigned long basejiff = ts->last_jiffies;

	u64 basemono = ts->timer_expires_base;

	bool timer_idle = tick_sched_flag_test(ts, TS_FLAG_STOPPED);

	int tick_cpu;

	u64 expires;



	/* Make sure we won't be trying to stop it twice in a row. */
@@ -1007,10 +1012,11 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) 
	 * do_timer() never gets invoked. Keep track of the fact that it

	 * was the one which had the do_timer() duty last.

	 */

	if (cpu == tick_do_timer_cpu) {

		tick_do_timer_cpu = TICK_DO_TIMER_NONE;

	tick_cpu = READ_ONCE(tick_do_timer_cpu);

	if (tick_cpu == cpu) {

		WRITE_ONCE(tick_do_timer_cpu, TICK_DO_TIMER_NONE);

		tick_sched_flag_set(ts, TS_FLAG_DO_TIMER_LAST);

	} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {

	} else if (tick_cpu != TICK_DO_TIMER_NONE) {

		tick_sched_flag_clear(ts, TS_FLAG_DO_TIMER_LAST);

	}
@@ -1173,15 +1179,17 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) 
		return false;



	if (tick_nohz_full_enabled()) {

		int tick_cpu = READ_ONCE(tick_do_timer_cpu);



		/*

		 * Keep the tick alive to guarantee timekeeping progression

		 * if there are full dynticks CPUs around

		 */

		if (tick_do_timer_cpu == cpu)

		if (tick_cpu == cpu)

			return false;



		/* Should not happen for nohz-full */

		if (WARN_ON_ONCE(tick_do_timer_cpu == TICK_DO_TIMER_NONE))

		if (WARN_ON_ONCE(tick_cpu == TICK_DO_TIMER_NONE))

			return false;

	}

tools/testing/selftests/kselftest.h

+27 −6
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ 
#include <stdarg.h>

#include <string.h>

#include <stdio.h>

#include <sys/utsname.h>

#endif



#ifndef ARRAY_SIZE
@@ -79,6 +80,9 @@ 
#define KSFT_XPASS 3

#define KSFT_SKIP  4



#ifndef __noreturn

#define __noreturn       __attribute__((__noreturn__))

#endif

#define __printf(a, b)   __attribute__((format(printf, a, b)))



/* counters */
@@ -299,13 +303,13 @@ void ksft_test_result_code(int exit_code, const char *test_name, 
	va_end(args);

}



static inline int ksft_exit_pass(void)

static inline __noreturn int ksft_exit_pass(void)

{

	ksft_print_cnts();

	exit(KSFT_PASS);

}



static inline int ksft_exit_fail(void)

static inline __noreturn int ksft_exit_fail(void)

{

	ksft_print_cnts();

	exit(KSFT_FAIL);
@@ -332,7 +336,7 @@ static inline int ksft_exit_fail(void) 
		  ksft_cnt.ksft_xfail +	\

		  ksft_cnt.ksft_xskip)



static inline __printf(1, 2) int ksft_exit_fail_msg(const char *msg, ...)

static inline __noreturn __printf(1, 2) int ksft_exit_fail_msg(const char *msg, ...)

{

	int saved_errno = errno;

	va_list args;
@@ -347,19 +351,19 @@ static inline __printf(1, 2) int ksft_exit_fail_msg(const char *msg, ...) 
	exit(KSFT_FAIL);

}



static inline int ksft_exit_xfail(void)

static inline __noreturn int ksft_exit_xfail(void)

{

	ksft_print_cnts();

	exit(KSFT_XFAIL);

}



static inline int ksft_exit_xpass(void)

static inline __noreturn int ksft_exit_xpass(void)

{

	ksft_print_cnts();

	exit(KSFT_XPASS);

}



static inline __printf(1, 2) int ksft_exit_skip(const char *msg, ...)

static inline __noreturn __printf(1, 2) int ksft_exit_skip(const char *msg, ...)

{

	int saved_errno = errno;

	va_list args;
@@ -388,4 +392,21 @@ static inline __printf(1, 2) int ksft_exit_skip(const char *msg, ...) 
	exit(KSFT_SKIP);

}



static inline int ksft_min_kernel_version(unsigned int min_major,

					  unsigned int min_minor)

{

#ifdef NOLIBC

	ksft_print_msg("NOLIBC: Can't check kernel version: Function not implemented\n");

	return 0;

#else

	unsigned int major, minor;

	struct utsname info;



	if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)

		ksft_exit_fail_msg("Can't parse kernel version\n");



	return major > min_major || (major == min_major && minor >= min_minor);

#endif

}



#endif /* __KSELFTEST_H */