[ltt-dev] [UST PATCH] libust: New transport mutex v2

[Nils Carlson]

Nils Carlson wrote:
> Changes since v1:
> 	Add a nesting comment
>
> Make the locking around the transport list more intelligent, give
> it its own mutex.
>
> Signed-off-by: Nils Carlson <nils.carlson at ericsson.com>
>   
and merged. I'll continue trying to fix things here... I don't need fine 
grained locking. But I think its reasonable that we can lock on a 
per-trace basis eventually at least, so multiple different traces can be 
modified simultaneously. We'll see how it goes though. No hurry.

/Nils
> ---
>  libust/tracer.c |   14 +++++++++-----
>  1 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/libust/tracer.c b/libust/tracer.c
> index 100dec0..ffcc2e7 100644
> --- a/libust/tracer.c
> +++ b/libust/tracer.c
> @@ -182,7 +182,8 @@ static enum ltt_channels get_channel_type_from_name(const char *name)
>  //ust// }
>  
>  static CDS_LIST_HEAD(ltt_transport_list);
> -
> +/* transport mutex, nests inside traces mutex (ltt_lock_traces) */
> +static DEFINE_MUTEX(ltt_transport_mutex);
>  /**
>   * ltt_transport_register - LTT transport registration
>   * @transport: transport structure
> @@ -204,9 +205,9 @@ void ltt_transport_register(struct ltt_transport *transport)
>  	 */
>  //ust//	vmalloc_sync_all();
>  
> -	ltt_lock_traces();
> +	pthread_mutex_lock(&ltt_transport_mutex);
>  	cds_list_add_tail(&transport->node, &ltt_transport_list);
> -	ltt_unlock_traces();
> +	pthread_mutex_unlock(&ltt_transport_mutex);
>  }
>  
>  /**
> @@ -215,9 +216,9 @@ void ltt_transport_register(struct ltt_transport *transport)
>   */
>  void ltt_transport_unregister(struct ltt_transport *transport)
>  {
> -	ltt_lock_traces();
> +	pthread_mutex_lock(&ltt_transport_mutex);
>  	cds_list_del(&transport->node);
> -	ltt_unlock_traces();
> +	pthread_mutex_unlock(&ltt_transport_mutex);
>  }
>  
>  static inline int is_channel_overwrite(enum ltt_channels chan,
> @@ -458,12 +459,15 @@ int ltt_trace_set_type(const char *trace_name, const char *trace_type)
>  		goto traces_error;
>  	}
>  
> +	pthread_mutex_lock(&ltt_transport_mutex);
>  	cds_list_for_each_entry(tran_iter, &ltt_transport_list, node) {
>  		if (!strcmp(tran_iter->name, trace_type)) {
>  			transport = tran_iter;
>  			break;
>  		}
>  	}
> +	pthread_mutex_unlock(&ltt_transport_mutex);
> +
>  	if (!transport) {
>  		ERR("Transport %s is not present", trace_type);
>  		err = -EINVAL;
>