Commit 1b267793 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

time/timekeeping: Avoid invoking clock_was_set() twice 



do_adjtimex() might end up scheduling a delayed clock_was_set() via
timekeeping_advance() and then invoke clock_was_set() directly which is
pointless.

Make timekeeping_advance() return whether an invocation of clock_was_set()
is required and handle it at the call sites which allows do_adjtimex() to
issue a single direct call if required.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.580966888@linutronix.de
parent a761a67f

kernel/time/timekeeping.c

+10 −8
Original line number Diff line number Diff line
@@ -2127,7 +2127,7 @@ static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset, 
 * timekeeping_advance - Updates the timekeeper to the current time and

 * current NTP tick length

 */

static void timekeeping_advance(enum timekeeping_adv_mode mode)

static bool timekeeping_advance(enum timekeeping_adv_mode mode)

{

	struct timekeeper *real_tk = &tk_core.timekeeper;

	struct timekeeper *tk = &shadow_timekeeper;
@@ -2198,9 +2198,8 @@ static void timekeeping_advance(enum timekeeping_adv_mode mode) 
	write_seqcount_end(&tk_core.seq);

out:

	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);

	if (clock_set)

		/* Have to call _delayed version, since in irq context*/

		clock_was_set_delayed();



	return !!clock_set;

}



/**
@@ -2209,7 +2208,8 @@ static void timekeeping_advance(enum timekeeping_adv_mode mode) 
 */

void update_wall_time(void)

{

	timekeeping_advance(TK_ADV_TICK);

	if (timekeeping_advance(TK_ADV_TICK))

		clock_was_set_delayed();

}



/**
@@ -2389,8 +2389,9 @@ int do_adjtimex(struct __kernel_timex *txc) 
{

	struct timekeeper *tk = &tk_core.timekeeper;

	struct audit_ntp_data ad;

	unsigned long flags;

	bool clock_set = false;

	struct timespec64 ts;

	unsigned long flags;

	s32 orig_tai, tai;

	int ret;
@@ -2425,6 +2426,7 @@ int do_adjtimex(struct __kernel_timex *txc) 
	if (tai != orig_tai) {

		__timekeeping_set_tai_offset(tk, tai);

		timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);

		clock_set = true;

	}

	tk_update_leap_state(tk);
@@ -2435,9 +2437,9 @@ int do_adjtimex(struct __kernel_timex *txc) 


	/* Update the multiplier immediately if frequency was set directly */

	if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))

		timekeeping_advance(TK_ADV_FREQ);

		clock_set |= timekeeping_advance(TK_ADV_FREQ);



	if (tai != orig_tai)

	if (clock_set)

		clock_was_set();



	ntp_notify_cmos_timer();