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

Ruhl, Michael J
2017-11-16T12:09:19Z

Hmm,

I don't know where my cover letter went for this patch set.

v4 cleans up the suggested type casting issues in this patch.

Thanks,
Mike

> -----Original Message-----
> From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma-
> owner@vger.kernel.org] On Behalf Of Michael J. Ruhl
> Sent: Wednesday, November 15, 2017 2:36 PM
> To: linux-rdma@vger.kernel.org
> Subject: [PATCH rdma-core v4 4/4] ibacm: Use MONOTONIC time base to avoid
> timer expiration issues
>
> From: Michael J. Ruhl <michael.j.ruhl@intel.com>
>
> 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@intel.com>
> Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
> ---
> 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)
>
> --
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