If DPDK is built with thread sanitizer it reports a race
in setting of multiprocess file descriptor. The fix is to
use atomic operations when updating mp_fd.
Simple example:
$ dpdk-testpmd -l 1-3 --no-huge
...
EAL: Error - exiting with code: 1
Cause: Creation of mbuf pool for socket 0 failed: Cannot allocate memory
==================
WARNING: ThreadSanitizer: data race (pid=83054)
Write of size 4 at 0x55e3b7fce450 by main thread:
#0 rte_mp_channel_cleanup <null> (dpdk-testpmd+0x160d79c)
#1 rte_eal_cleanup <null> (dpdk-testpmd+0x1614fb5)
#2 rte_exit <null> (dpdk-testpmd+0x15ec97a)
#3 mbuf_pool_create.cold <null> (dpdk-testpmd+0x242e1a)
#4 main <null> (dpdk-testpmd+0x5ab05d)
Previous read of size 4 at 0x55e3b7fce450 by thread T2:
#0 mp_handle <null> (dpdk-testpmd+0x160c979)
#1 ctrl_thread_init <null> (dpdk-testpmd+0x15ff76e)
As if synchronized via sleep:
#0 nanosleep
../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:362
(libtsan.so.0+0x5cd8e)
#1 get_tsc_freq <null> (dpdk-testpmd+0x1622889)
#2 set_tsc_freq <null> (dpdk-testpmd+0x15ffb9c)
#3 rte_eal_timer_init <null> (dpdk-testpmd+0x1622a34)
#4 rte_eal_init.cold <null> (dpdk-testpmd+0x26b314)
#5 main <null> (dpdk-testpmd+0x5aab45)
Location is global 'mp_fd' of size 4 at 0x55e3b7fce450
(dpdk-testpmd+0x0000027c7450)
Thread T2 'rte_mp_handle' (tid=83057, running) created by main thread at:
#0 pthread_create
../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:962
(libtsan.so.0+0x58ba2)
#1 rte_ctrl_thread_create <null> (dpdk-testpmd+0x15ff870)
#2 rte_mp_channel_init.cold <null> (dpdk-testpmd+0x269986)
#3 rte_eal_init <null> (dpdk-testpmd+0x1615b28)
#4 main <null> (dpdk-testpmd+0x5aab45)
SUMMARY: ThreadSanitizer: data race
(/home/shemminger/DPDK/main/build/app/dpdk-testpmd+0x160d79c) in
rte_mp_channel_cleanup
==================
ThreadSanitizer: reported 1 warnings
Fixes: bacaa2754017 ("eal: add channel for multi-process communication")
Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
---
v2 - fix the mp socket bind
lib/eal/common/eal_common_proc.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/lib/eal/common/eal_common_proc.c b/lib/eal/common/eal_common_proc.c
index ebd0f6673b8b..72c7e8f536af 100644
--- a/lib/eal/common/eal_common_proc.c
+++ b/lib/eal/common/eal_common_proc.c
@@ -262,7 +262,7 @@ rte_mp_action_unregister(const char *name)
}
static int
-read_msg(struct mp_msg_internal *m, struct sockaddr_un *s)
+read_msg(int fd, struct mp_msg_internal *m, struct sockaddr_un *s)
{
int msglen;
struct iovec iov;
@@ -282,7 +282,7 @@ read_msg(struct mp_msg_internal *m, struct sockaddr_un *s)
msgh.msg_control = control;
msgh.msg_controllen = sizeof(control);
- msglen = recvmsg(mp_fd, &msgh, 0);
+ msglen = recvmsg(fd, &msgh, 0);
if (msglen < 0) {
RTE_LOG(ERR, EAL, "recvmsg failed, %s\n", strerror(errno));
return -1;
@@ -383,9 +383,10 @@ mp_handle(void *arg __rte_unused)
{
struct mp_msg_internal msg;
struct sockaddr_un sa;
+ int fd;
- while (mp_fd >= 0) {
- if (read_msg(&msg, &sa) == 0)
+ while ((fd = __atomic_load_n(&mp_fd, __ATOMIC_RELAXED)) >= 0) {
+ if (read_msg(fd, &msg, &sa) == 0)
process_msg(&msg, &sa);
}
@@ -626,9 +627,8 @@ rte_mp_channel_init(void)
NULL, mp_handle, NULL) < 0) {
RTE_LOG(ERR, EAL, "failed to create mp thread: %s\n",
strerror(errno));
- close(mp_fd);
close(dir_fd);
- mp_fd = -1;
+ close(__atomic_exchange_n(&mp_fd, -1, __ATOMIC_RELAXED));
return -1;
}
@@ -644,11 +644,10 @@ rte_mp_channel_cleanup(void)
{
int fd;
- if (mp_fd < 0)
+ fd = __atomic_exchange_n(&mp_fd, -1, __ATOMIC_RELAXED);
+ if (fd < 0)
return;
- fd = mp_fd;
- mp_fd = -1;
pthread_cancel(mp_handle_tid);
pthread_join(mp_handle_tid, NULL);
close_socket_fd(fd);
--
2.30.2
