Merged, thanks !
Julien
On 23-Aug-2016 11:44:45 PM, Mathieu Desnoyers wrote:
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
> ---
> tracker_private.h | 3 ++-
> wrapper/freelist-ll.h | 21 +++++++++++++++------
> 2 files changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/tracker_private.h b/tracker_private.h
> index 03386b8..fc27f80 100644
> --- a/tracker_private.h
> +++ b/tracker_private.h
> @@ -7,6 +7,7 @@
>
> #include <linux/workqueue.h>
> #include <linux/irq_work.h>
> +#include <asm/local.h>
>
> //#include "wrapper/ht.h"
> //#include "rculfhash-internal.h"
> @@ -18,7 +19,7 @@ struct numa_pool {
> };
>
> struct per_cpu_ll {
> - int current_count;
> + local_t current_count;
> struct numa_pool *pool;
> struct llist_head llist;
> };
> diff --git a/wrapper/freelist-ll.h b/wrapper/freelist-ll.h
> index 5e4d18e..44db722 100644
> --- a/wrapper/freelist-ll.h
> +++ b/wrapper/freelist-ll.h
> @@ -242,8 +242,8 @@ int free_per_cpu_llist(struct latency_tracker *tracker)
> if (!list)
> continue;
> cnt = free_event_list(list);
> - printk("freed %d on cpu %d (%d)\n", cnt, cpu,
> - ll->current_count);
> + printk("freed %d on cpu %d (%ld)\n", cnt, cpu,
> + local_read(&ll->current_count));
> total_cnt += cnt;
> }
>
> @@ -284,10 +284,14 @@ struct llist_node *per_cpu_get(struct latency_tracker
> *tracker)
> struct per_cpu_ll *ll;
>
> ll = lttng_this_cpu_ptr(tracker->per_cpu_ll);
> + /*
> + * Decrement the current count after we successfully remove an
> + * element from the list.
> + */
> node = llist_del_first(&ll->llist);
> if (node) {
> - ll->current_count--;
> - WARN_ON_ONCE(ll->current_count < 0);
> + local_dec(&ll->current_count);
> + WARN_ON_ONCE(local_read(&ll->current_count) < 0);
> return node;
> }
> return llist_del_first(&ll->pool->llist);
> @@ -336,12 +340,17 @@ void __wrapper_freelist_put_event(struct
> latency_tracker *tracker,
> if (e->pool != ll->pool) {
> // printk("DEBUG cross-pool put_event\n");
> llist_add(&e->llist, &ll->pool->llist);
> - } else if (ll->current_count < FREELIST_PERCPU_CACHE) {
> + } else if (local_read(&ll->current_count) < FREELIST_PERCPU_CACHE) {
> /*
> * Fill our local cache if needed.
> + * We need to increment current_count before we add the
> + * element to the list, because when we successfully
> + * remove an element from the list, we expect that the
> + * counter is never negative. An interrupt can observe
> + * the intermediate state.
> */
> + local_inc(&ll->current_count);
> llist_add(&e->llist, &ll->llist);
> - ll->current_count++;
> } else {
> /*
> * Add to our NUMA pool.
> --
> 2.1.4
>
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