On 6/1/2026 2:40 PM, Thomas Monjalon wrote:
01/06/2026 14:21, Thomas Monjalon:
29/05/2026 17:26, Anatoly Burakov:
Currently, when rte_mp_request_async() is called and no peer processes
are connected (nb_sent == 0), the user callback is never invoked.
The original implementation used a dedicated background thread and
pthread_cond_signal() to wake it after queuing the dummy request. When
that thread was replaced with per-message alarms, no alarm was set for
the dummy request, silently breaking the nb_sent == 0 path.
This was not noticed because async requests are used while handling
secondary process requests, where peers are typically already present.
Fix it by setting a 1us alarm on the dummy request, so the callback path
immediately triggers and processes it.
Fixes: daf9bfca717e ("ipc: remove thread for async requests")
Cc: [email protected]
Signed-off-by: Anatoly Burakov <[email protected]>
---
lib/eal/common/eal_common_proc.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/lib/eal/common/eal_common_proc.c b/lib/eal/common/eal_common_proc.c
index 799c6e81b0..0ec79336a5 100644
--- a/lib/eal/common/eal_common_proc.c
+++ b/lib/eal/common/eal_common_proc.c
@@ -1187,11 +1187,15 @@ rte_mp_request_async(struct rte_mp_msg *req, const
struct timespec *ts,
if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
ret = mp_request_async(eal_mp_socket_path(), copy, param, ts);
- /* if we didn't send anything, put dummy request on the queue */
+ /* if we didn't send anything, put dummy request on the queue
+ * and set a minimum-delay alarm so the callback fires
immediately.
+ */
if (ret == 0 && reply->nb_sent == 0) {
TAILQ_INSERT_TAIL(&pending_requests.requests, dummy,
next);
dummy_used = true;
+ if (rte_eal_alarm_set(1, async_reply_handle, dummy) < 0)
+ EAL_LOG(ERR, "Fail to set alarm for dummy
request");
Shouldn't we return an error?
AI suggests this:
if (rte_eal_alarm_set(1, async_reply_handle,
(void *)(uintptr_t)dummy->id) < 0) {
EAL_LOG(ERR, "Fail to set alarm for dummy request");
TAILQ_REMOVE(&pending_requests.requests, dummy, next);
dummy_used = false;
ret = -1;
}
Dummy id is not added till later in the series, but I'll integrate this
otherwise.
--
Thanks,
Anatoly
