Commit 7a4ed937 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] Fix cpu timers expiration time

There's a silly off-by-one error in the code that updates the expiration
of posix CPU timers, causing them to not be properly updated when they
hit exactly on their expiration time (which should be the normal case).

This causes them to then fire immediately again, and only _then_ get
properly updated.
Signed-off-by: default avatarLinus Torvalds <>
parent e02fd440
......@@ -91,7 +91,7 @@ static inline union cpu_time_count cpu_time_sub(clockid_t which_clock,
* Update expiry time from increment, and increase overrun count,
* given the current clock sample.
static inline void bump_cpu_timer(struct k_itimer *timer,
static void bump_cpu_timer(struct k_itimer *timer,
union cpu_time_count now)
int i;
......@@ -110,7 +110,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer,
for (i = 0; incr < delta - incr; i++)
incr = incr << 1;
for (; i >= 0; incr >>= 1, i--) {
if (delta <= incr)
if (delta < incr)
timer->it.cpu.expires.sched += incr;
timer->it_overrun += 1 << i;
......@@ -128,7 +128,7 @@ static inline void bump_cpu_timer(struct k_itimer *timer,
for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
incr = cputime_add(incr, incr);
for (; i >= 0; incr = cputime_halve(incr), i--) {
if (cputime_le(delta, incr))
if (cputime_lt(delta, incr))
timer->it.cpu.expires.cpu =
cputime_add(timer->it.cpu.expires.cpu, incr);
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