On Wed, Oct 01, 2014 at 03:20:22PM +0100, Pawel Wodkowski wrote:
> v3:
> Set rte_errno inside rte_alarm_cancel() to inform caller about canceling
> result.
>
> v2:
> Eliminate a race between rte_alarm_set() used in context of executing callback
> function and other threads that use rte_alarm_cancel().
>
> Signed-off-by: Pawel Wodkowski <pawelx.wodkowski at intel.com>
> ---
> lib/librte_eal/common/include/rte_alarm.h | 12 ++++-
> lib/librte_eal/linuxapp/eal/eal_alarm.c | 83
> ++++++++++++++++++++---------
> 2 files changed, 68 insertions(+), 27 deletions(-)
>
> diff --git a/lib/librte_eal/common/include/rte_alarm.h
> b/lib/librte_eal/common/include/rte_alarm.h
> index d451522..d5d4e9d 100644
> --- a/lib/librte_eal/common/include/rte_alarm.h
> +++ b/lib/librte_eal/common/include/rte_alarm.h
> @@ -76,7 +76,8 @@ typedef void (*rte_eal_alarm_callback)(void *arg);
> int rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb, void *cb_arg);
>
> /**
> - * Function to cancel an alarm callback which has been registered before.
> + * Function to cancel an alarm callback which has been registered before. If
> + * used outside alarm callback it wait for all callbacks to finish execution.
> *
> * @param cb_fn
> * alarm callback
> @@ -86,7 +87,14 @@ int rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback
> cb, void *cb_arg);
> * can be used here.
> *
> * @return
> - * - The number of callbacks removed
> + * - value greater than 0 and rte_errno not changed - returned value is
> + * the number of canceled alarm callback functions
> + * - value greater or equal 0 and rte_errno set to EINPROGRESS, at least
> one
> + * alarm could not be canceled because cancelation was requested from
> alarm
> + * callback context. Returned value is the number of succesfuly canceled
> + * alarm callbacks
> + * - 0 and rte_errno set to ENOENT - no alarm found
> + * - -1 and rte_errno set to EINVAL - invalid parameter (NULL callback)
> */
> int rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, void *cb_arg);
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal_alarm.c
> b/lib/librte_eal/linuxapp/eal/eal_alarm.c
> index 480f0cb..4801650 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_alarm.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_alarm.c
> @@ -69,7 +69,8 @@ struct alarm_entry {
> struct timeval time;
> rte_eal_alarm_callback cb_fn;
> void *cb_arg;
> - volatile int executing;
> + volatile uint8_t executing;
> + volatile pthread_t executing_id;
> };
>
> static LIST_HEAD(alarm_list, alarm_entry) alarm_list =
> LIST_HEAD_INITIALIZER();
> @@ -108,11 +109,13 @@ eal_alarm_callback(struct rte_intr_handle *hdl
> __rte_unused,
> (ap->time.tv_sec < now.tv_sec || (ap->time.tv_sec ==
> now.tv_sec &&
> ap->time.tv_usec <=
> now.tv_usec))){
> ap->executing = 1;
> + ap->executing_id = pthread_self();
> rte_spinlock_unlock(&alarm_list_lk);
>
> ap->cb_fn(ap->cb_arg);
>
> rte_spinlock_lock(&alarm_list_lk);
> +
> LIST_REMOVE(ap, next);
> rte_free(ap);
> }
> @@ -145,7 +148,7 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback
> cb_fn, void *cb_arg)
> if (us < 1 || us > (UINT64_MAX - US_PER_S) || cb_fn == NULL)
> return -EINVAL;
>
> - new_alarm = rte_malloc(NULL, sizeof(*new_alarm), 0);
> + new_alarm = rte_zmalloc(NULL, sizeof(*new_alarm), 0);
> if (new_alarm == NULL)
> return -ENOMEM;
>
> @@ -156,7 +159,6 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback
> cb_fn, void *cb_arg)
> new_alarm->cb_arg = cb_arg;
> new_alarm->time.tv_usec = (now.tv_usec + us) % US_PER_S;
> new_alarm->time.tv_sec = now.tv_sec + ((now.tv_usec + us) / US_PER_S);
> - new_alarm->executing = 0;
>
> rte_spinlock_lock(&alarm_list_lk);
> if (!handler_registered) {
> @@ -202,34 +204,65 @@ rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, void
> *cb_arg)
> {
> struct alarm_entry *ap, *ap_prev;
> int count = 0;
> + int err = 0;
> + int executing;
>
> - if (!cb_fn)
> + if (!cb_fn) {
> + rte_errno = EINVAL;
> return -1;
> -
> - rte_spinlock_lock(&alarm_list_lk);
> - /* remove any matches at the start of the list */
> - while ((ap = LIST_FIRST(&alarm_list)) != NULL &&
> - cb_fn == ap->cb_fn && ap->executing == 0 &&
> - (cb_arg == (void *)-1 || cb_arg == ap->cb_arg)) {
> - LIST_REMOVE(ap, next);
> - rte_free(ap);
> - count++;
> }
> - ap_prev = ap;
>
> - /* now go through list, removing entries not at start */
> - LIST_FOREACH(ap, &alarm_list, next) {
> - /* this won't be true first time through */
> - if (cb_fn == ap->cb_fn && ap->executing == 0 &&
> + do {
> + executing = 0;
> + rte_spinlock_lock(&alarm_list_lk);
> + /* remove any matches at the start of the list */
> + while ((ap = LIST_FIRST(&alarm_list)) != NULL &&
> + cb_fn == ap->cb_fn &&
> (cb_arg == (void *)-1 || cb_arg == ap->cb_arg))
> {
> - LIST_REMOVE(ap,next);
> - rte_free(ap);
> - count++;
> - ap = ap_prev;
> +
> + if (ap->executing == 0) {
> + LIST_REMOVE(ap, next);
> + rte_free(ap);
> + count++;
> + } else {
> + /* If calling from other context, mark that
> alarm is executing
> + * so loop can spin till it finish. Otherwise
> we are trying to
> + * cancel our self - mark it by EINPROGRESS */
> + if (pthread_equal(ap->executing_id,
> pthread_self()) == 0)
> + executing++;
> + else
> + err = EINPROGRESS;
> +
> + break;
> + }
> }
> ap_prev = ap;
> - }
> - rte_spinlock_unlock(&alarm_list_lk);
> +
> + /* now go through list, removing entries not at start */
> + LIST_FOREACH(ap, &alarm_list, next) {
> + /* this won't be true first time through */
> + if (cb_fn == ap->cb_fn &&
> + (cb_arg == (void *)-1 || cb_arg ==
> ap->cb_arg)) {
> +
> + if (ap->executing == 0) {
> + LIST_REMOVE(ap,next);
> + rte_free(ap);
> + count++;
> + ap = ap_prev;
> + } else if (pthread_equal(ap->executing_id,
> pthread_self()) == 0)
> + executing++;
> + else
> + err = EINPROGRESS;
> + }
> + ap_prev = ap;
> + }
> + rte_spinlock_unlock(&alarm_list_lk);
> + } while (executing != 0);
> +
> + if (count == 0 && err == 0)
> + rte_errno = ENOENT;
> + else if (err)
> + rte_errno = err;
> +
> return count;
> }
> -
> --
> 1.7.9.5
>
>
Much better, thanks!
Acked-by: Neil Horman <nhorman at tuxdriver.com>
