Re: [dpdk-dev] [PATCH v3 3/5] eal: set name when creating a control thread

[Tan, Jianfeng]

Hi Olivier,

After this patch, I find the two IPC threads block at 
pthread_barrier_wait(), and never wake up. Please refer below for more 
information. The system is Ubuntu 16.04.

On 4/24/2018 10:46 PM, Olivier Matz wrote:
To avoid code duplication, add a parameter to rte_ctrl_thread_create()
to specify the name of the thread.

This requires to add a wrapper for the thread start routine in
rte_thread_init(), which will first wait that the thread is configured.

Signed-off-by: Olivier Matz <olivier.m...@6wind.com>
---
  drivers/net/kni/rte_eth_kni.c                |  3 +-
  lib/librte_eal/common/eal_common_proc.c      | 15 +++-----
  lib/librte_eal/common/eal_common_thread.c    | 52 +++++++++++++++++++++++++---
  lib/librte_eal/common/include/rte_lcore.h    |  7 ++--
  lib/librte_eal/linuxapp/eal/eal_interrupts.c | 13 ++-----
  lib/librte_eal/linuxapp/eal/eal_timer.c      | 12 +------
  lib/librte_vhost/socket.c                    | 25 +++----------
  7 files changed, 66 insertions(+), 61 deletions(-)
[...]
diff --git a/lib/librte_eal/common/eal_common_thread.c 
b/lib/librte_eal/common/eal_common_thread.c
index efbccddbc..94d2a6e42 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -7,6 +7,7 @@
  #include <stdint.h>
  #include <unistd.h>
  #include <pthread.h>
+#include <signal.h>
  #include <sched.h>
  #include <assert.h>
  #include <string.h>
@@ -141,10 +142,53 @@ eal_thread_dump_affinity(char *str, unsigned size)
        return ret;
  }
  
+
+struct rte_thread_ctrl_params {
+       void *(*start_routine)(void *);
+       void *arg;
+       pthread_barrier_t configured;
+};
+
+static void *rte_thread_init(void *arg)
+{
+       struct rte_thread_ctrl_params *params = arg;
+       void *(*start_routine)(void *) = params->start_routine;
+       void *routine_arg = params->arg;
+
+       pthread_barrier_wait(&params->configured);

This thread never wakes up. The call trace as below:

#0  0x00007ffff72a8154 in futex_wait (private=0, expected=0, 
futex_word=0x7fffffffcff4)
    at ../sysdeps/unix/sysv/linux/futex-internal.h:61
#1  futex_wait_simple (private=0, expected=0, futex_word=0x7fffffffcff4) 
at ../sysdeps/nptl/futex-internal.h:135
#2  __pthread_barrier_wait (barrier=0x7fffffffcff0) at 
pthread_barrier_wait.c:184
#3  0x000000000055216a in rte_thread_init (arg=0x7fffffffcfe0) at 
/home/tan/git/dpdk/lib/librte_eal/common/eal_common_thread.c:160
#4  0x00007ffff72a16ba in start_thread (arg=0x7ffff6ecf700) at 
pthread_create.c:333
#5  0x00007ffff6fd741d in clone () at 
../sysdeps/unix/sysv/linux/x86_64/clone.S:109

+
+       return start_routine(routine_arg);
+}
+
  __rte_experimental int
-rte_ctrl_thread_create(pthread_t *thread,
-                       const pthread_attr_t *attr,
-                       void *(*start_routine)(void *), void *arg)
+rte_ctrl_thread_create(pthread_t *thread, const char *name,
+               const pthread_attr_t *attr,
+               void *(*start_routine)(void *), void *arg)
  {
-       return pthread_create(thread, attr, start_routine, arg);
+       struct rte_thread_ctrl_params params = {
+               .start_routine = start_routine,
+               .arg = arg,
+       };
+       int ret;
+
+       pthread_barrier_init(&params.configured, NULL, 2);
+
+       ret = pthread_create(thread, attr, rte_thread_init, (void *)&params);
+       if (ret != 0)
+               return ret;
+
+       if (name != NULL) {
+               ret = rte_thread_setname(*thread, name);
+               if (ret < 0)
+                       goto fail;
+       }
+
+       pthread_barrier_wait(&params.configured);

Here, the thread wakes up normally, and continues.

Any idea on what's going on?

Thanks,
Jianfeng

+
+       return 0;
+
+fail:
+       pthread_cancel(*thread);
+       pthread_join(*thread, NULL);
+       return ret;
  }