[PATCH rdma-core v4 4/4] ibacm: Use MONOTONIC time base to avoid timer expiration issues

Michael J. Ruhl
2017-11-15T19:35:35Z

The event_wait() function uses the CLOCK_REALTIME time base for
calculating expiration times (default time base for gettimeofday()).

Using the CLOCK_REALTIME time base can introduce incorrect expiration
timeout calculations if the REALTIME clock changes, making a timeout
too long (possibly hours or days), or too short.

Update time base usage to the CLOCK_MONOTONIC time base to avoid time
change issues.

Use appropriate typing to avoid unnecessary typecasting.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
ibacm/linux/osd.h | 22 ++++++++++++----------
1 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/ibacm/linux/osd.h b/ibacm/linux/osd.h
index eabf5ed..4ef7b55 100644
--- a/ibacm/linux/osd.h
+++ b/ibacm/linux/osd.h
@@ -88,20 +88,23 @@ typedef struct { volatile int val; } atomic_t;
typedef struct { pthread_cond_t cond; pthread_mutex_t mutex; } event_t;
static inline void event_init(event_t *e)
{
- pthread_cond_init(&e->cond, NULL);
+ pthread_condattr_t attr;
+
+ pthread_condattr_init(&attr);
+ pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
+ pthread_cond_init(&e->cond, &attr);
pthread_mutex_init(&e->mutex, NULL);
}
#define event_signal(e) pthread_cond_signal(&(e)->cond)
#define ONE_SEC_IN_NSEC 1000000000ULL
-static inline int event_wait(event_t *e, int timeout)
+static inline int event_wait(event_t *e, unsigned int timeout)
{
- struct timeval curtime;
struct timespec wait;
int ret;

- gettimeofday(&curtime, NULL);
- wait.tv_sec = curtime.tv_sec + ((unsigned) timeout) / 1000;
- wait.tv_nsec = (curtime.tv_usec + (((unsigned) timeout) % 1000) * 1000) * 1000;
+ clock_gettime(CLOCK_MONOTONIC, &wait);
+ wait.tv_sec = wait.tv_sec + timeout / 1000;
+ wait.tv_nsec = wait.tv_nsec + (timeout % 1000) * 1000000;
if (wait.tv_nsec > ONE_SEC_IN_NSEC) {
wait.tv_sec++;
wait.tv_nsec -= ONE_SEC_IN_NSEC;
@@ -114,10 +117,9 @@ static inline int event_wait(event_t *e, int timeout)

static inline uint64_t time_stamp_us(void)
{
- struct timeval curtime;
- timerclear(&curtime);
- gettimeofday(&curtime, NULL);
- return (uint64_t) curtime.tv_sec * 1000000 + (uint64_t) curtime.tv_usec;
+ struct timespec t;
+ clock_gettime(CLOCK_MONOTONIC, &t);
+ return (t.tv_sec * ONE_SEC_IN_NSEC + t.tv_nsec) / 1000;
}

#define time_stamp_ms() (time_stamp_us() / (uint64_t) 1000)