[dpdk-dev] [PATCH 2/2] eal: fix hang in ctrl thread creation error logic
Luc Pelletier
lucp.at.work at gmail.com
Wed Apr 7 22:16:06 CEST 2021
The affinity of a control thread is set after it has been launched. If
setting the affinity fails, pthread_cancel is called followed by a call
to pthread_join, which can hang forever if the thread's start routine
doesn't call a pthread cancellation point.
This patch modifies the logic so that the control thread exits
gracefully if the affinity cannot be set successfully and removes the
call to pthread_cancel.
Fixes: 6383d26 ("eal: set name when creating a control thread")
Cc: olivier.matz at 6wind.com
Cc: stable at dpdk.org
Signed-off-by: Luc Pelletier <lucp.at.work at gmail.com>
---
Hi Olivier,
Hi Honnappa,
As discussed, I've split the changes into 2 patches. This second commit
removes the pthread_cancel call which could result in a hang on join, if
the ctrl thread routine didn't call a cancellation point.
lib/librte_eal/common/eal_common_thread.c | 29 +++++++++++++----------
1 file changed, 17 insertions(+), 12 deletions(-)
diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index 3347e91bf..03dbcd9e8 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -187,14 +187,18 @@ static void *ctrl_thread_init(void *arg)
eal_get_internal_configuration();
rte_cpuset_t *cpuset = &internal_conf->ctrl_cpuset;
struct rte_thread_ctrl_params *params = arg;
- void *(*start_routine)(void *) = params->start_routine;
+ void *(*start_routine)(void *);
void *routine_arg = params->arg;
__rte_thread_init(rte_lcore_id(), cpuset);
pthread_barrier_wait(¶ms->configured);
+ start_routine = params->start_routine;
ctrl_params_free(params);
+ if (start_routine == NULL)
+ return NULL;
+
return start_routine(routine_arg);
}
@@ -218,14 +222,12 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
params->refcnt = 2;
ret = pthread_barrier_init(¶ms->configured, NULL, 2);
- if (ret != 0) {
- free(params);
- return -ret;
- }
+ if (ret != 0)
+ goto fail_no_barrier;
ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params);
if (ret != 0)
- goto fail;
+ goto fail_with_barrier;
if (name != NULL) {
ret = rte_thread_setname(*thread, name);
@@ -236,19 +238,22 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
ret = pthread_setaffinity_np(*thread, sizeof(*cpuset), cpuset);
if (ret != 0)
- goto fail_cancel;
+ params->start_routine = NULL;
pthread_barrier_wait(¶ms->configured);
ctrl_params_free(params);
- return 0;
+ if (ret != 0)
+ /* start_routine has been set to NULL above; */
+ /* ctrl thread will exit immediately */
+ pthread_join(*thread, NULL);
-fail_cancel:
- pthread_cancel(*thread);
- pthread_join(*thread, NULL);
+ return -ret;
-fail:
+fail_with_barrier:
pthread_barrier_destroy(¶ms->configured);
+
+fail_no_barrier:
free(params);
return -ret;
--
2.25.1
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