The pmds and the main threads are synchronized using a condition
variable. The main thread writes a new configuration, then it waits on
the condition variable. A pmd thread reads the new configuration, then
it calls signal() on the condition variable. To make sure that the pmds
and the main thread have a consistent view, each signal() should be
backed by a wait().
Currently the first signal() doesn't have a corresponding wait(). If
the pmd thread takes a long time to start and the signal() is received
by a later wait, the threads will have an inconsistent view.
The commit fixes the problem by removing the first signal() from the
pmd thread.
This is hardly a problem on current master, because the main thread
will call the first wait() a long time after the creation of a pmd
thread. It becomes a problem with the next commits.
Signed-off-by: Daniele Di Proietto <diproiet...@vmware.com>
---
lib/dpif-netdev.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index c3be4eb..fbd23cf 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -2651,21 +2651,22 @@ dpif_netdev_wait(struct dpif *dpif)
static int
pmd_load_queues(struct dp_netdev_pmd_thread *pmd, struct rxq_poll **ppoll_list)
- OVS_REQUIRES(pmd->poll_mutex)
{
struct rxq_poll *poll_list = *ppoll_list;
struct rxq_poll *poll;
int i;
+ ovs_mutex_lock(&pmd->poll_mutex);
poll_list = xrealloc(poll_list, pmd->poll_cnt * sizeof *poll_list);
i = 0;
LIST_FOR_EACH (poll, node, &pmd->poll_list) {
poll_list[i++] = *poll;
}
+ ovs_mutex_unlock(&pmd->poll_mutex);
*ppoll_list = poll_list;
- return pmd->poll_cnt;
+ return i;
}
static void *
@@ -2675,6 +2676,7 @@ pmd_thread_main(void *f_)
unsigned int lc = 0;
struct rxq_poll *poll_list;
unsigned int port_seq = PMD_INITIAL_SEQ;
+ bool exiting;
int poll_cnt;
int i;
@@ -2684,13 +2686,10 @@ pmd_thread_main(void *f_)
/* Stores the pmd thread's 'pmd' to 'per_pmd_key'. */
ovsthread_setspecific(pmd->dp->per_pmd_key, pmd);
pmd_thread_setaffinity_cpu(pmd->core_id);
+ poll_cnt = pmd_load_queues(pmd, &poll_list);
reload:
emc_cache_init(&pmd->flow_cache);
- ovs_mutex_lock(&pmd->poll_mutex);
- poll_cnt = pmd_load_queues(pmd, &poll_list);
- ovs_mutex_unlock(&pmd->poll_mutex);
-
/* List port/core affinity */
for (i = 0; i < poll_cnt; i++) {
VLOG_DBG("Core %d processing port \'%s\' with queue-id %d\n",
@@ -2698,10 +2697,6 @@ reload:
netdev_rxq_get_queue_id(poll_list[i].rx));
}
- /* Signal here to make sure the pmd finishes
- * reloading the updated configuration. */
- dp_netdev_pmd_reload_done(pmd);
-
for (;;) {
for (i = 0; i < poll_cnt; i++) {
dp_netdev_process_rxq_port(pmd, poll_list[i].port,
poll_list[i].rx);
@@ -2724,14 +2719,18 @@ reload:
}
}
+ poll_cnt = pmd_load_queues(pmd, &poll_list);
+ exiting = latch_is_set(&pmd->exit_latch);
+ /* Signal here to make sure the pmd finishes
+ * reloading the updated configuration. */
+ dp_netdev_pmd_reload_done(pmd);
+
emc_cache_uninit(&pmd->flow_cache);
- if (!latch_is_set(&pmd->exit_latch)){
+ if (!exiting) {
goto reload;
}
- dp_netdev_pmd_reload_done(pmd);
-
free(poll_list);
return NULL;
}
--
2.1.4
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