Hi Anatoly,
> -----Original Message-----
> From: Burakov, Anatoly
> Sent: Tuesday, February 27, 2018 10:36 PM
> To: dev@dpdk.org
> Cc: Tan, Jianfeng
> Subject: [PATCH v3 4/5] eal: prevent secondary process init while sending
> messages
>
> Currently, it is possible to spin up a secondary process while
> either sendmsg or request is in progress. Fix this by adding
> directory locks during init, sendmsg and requests.
Could you give a more detailed example for this issue?
And why locking the directory can help?
Thanks,
Jianfeng
>
> Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
> ---
>
> Notes:
> v3: no changes
>
> v2: no changes
>
> lib/librte_eal/common/eal_common_proc.c | 47
> ++++++++++++++++++++++++++++++++-
> 1 file changed, 46 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/common/eal_common_proc.c
> b/lib/librte_eal/common/eal_common_proc.c
> index 7c87971..7856a7b 100644
> --- a/lib/librte_eal/common/eal_common_proc.c
> +++ b/lib/librte_eal/common/eal_common_proc.c
> @@ -507,6 +507,7 @@ rte_mp_channel_init(void)
> {
> char thread_name[RTE_MAX_THREAD_NAME_LEN];
> char *path;
> + int dir_fd;
> pthread_t tid;
>
> snprintf(mp_filter, PATH_MAX, ".%s_unix_*",
> @@ -516,14 +517,32 @@ rte_mp_channel_init(void)
> snprintf(mp_dir_path, PATH_MAX, "%s", dirname(path));
> free(path);
>
> + /* lock the directory */
> + dir_fd = open(mp_dir_path, O_RDONLY);
> + if (dir_fd < 0) {
> + RTE_LOG(ERR, EAL, "failed to open %s: %s\n",
> + mp_dir_path, strerror(errno));
> + return -1;
> + }
> +
> + if (flock(dir_fd, LOCK_EX)) {
> + RTE_LOG(ERR, EAL, "failed to lock %s: %s\n",
> + mp_dir_path, strerror(errno));
> + close(dir_fd);
> + return -1;
> + }
> +
> if (rte_eal_process_type() == RTE_PROC_PRIMARY &&
> unlink_sockets(mp_filter)) {
> RTE_LOG(ERR, EAL, "failed to unlink mp sockets\n");
> + close(dir_fd);
> return -1;
> }
>
> - if (open_socket_fd() < 0)
> + if (open_socket_fd() < 0) {
> + close(dir_fd);
> return -1;
> + }
>
> if (pthread_create(&tid, NULL, mp_handle, NULL) < 0) {
> RTE_LOG(ERR, EAL, "failed to create mp thead: %s\n",
> @@ -536,6 +555,11 @@ rte_mp_channel_init(void)
> /* try best to set thread name */
> snprintf(thread_name, RTE_MAX_THREAD_NAME_LEN,
> "rte_mp_handle");
> rte_thread_setname(tid, thread_name);
> +
> + /* unlock the directory */
> + flock(dir_fd, LOCK_UN);
> + close(dir_fd);
> +
> return 0;
> }
>
> @@ -650,6 +674,14 @@ mp_send(struct rte_mp_msg *msg, const char
> *peer, int type)
> return -1;
> }
> dir_fd = dirfd(mp_dir);
> + /* lock the directory to prevent processes spinning up while we send
> */
> + if (flock(dir_fd, LOCK_EX)) {
> + RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
> + mp_dir_path);
> + rte_errno = errno;
> + closedir(mp_dir);
> + return -1;
> + }
> while ((ent = readdir(mp_dir))) {
> char path[PATH_MAX];
> const char *peer_name;
> @@ -673,6 +705,8 @@ mp_send(struct rte_mp_msg *msg, const char *peer,
> int type)
> else if (active > 0 && send_msg(path, msg, type) < 0)
> ret = -1;
> }
> + /* unlock the dir */
> + flock(dir_fd, LOCK_UN);
>
> closedir(mp_dir);
> return ret;
> @@ -832,6 +866,15 @@ rte_mp_request(struct rte_mp_msg *req, struct
> rte_mp_reply *reply,
> }
> dir_fd = dirfd(mp_dir);
>
> + /* lock the directory to prevent processes spinning up while we send
> */
> + if (flock(dir_fd, LOCK_EX)) {
> + RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
> + mp_dir_path);
> + closedir(mp_dir);
> + rte_errno = errno;
> + return -1;
> + }
> +
> while ((ent = readdir(mp_dir))) {
> const char *peer_name;
> char path[PATH_MAX];
> @@ -857,6 +900,8 @@ rte_mp_request(struct rte_mp_msg *req, struct
> rte_mp_reply *reply,
> if (mp_request_one(path, req, reply, &end))
> ret = -1;
> }
> + /* unlock the directory */
> + flock(dir_fd, LOCK_UN);
>
> closedir(mp_dir);
> return ret;
> --
> 2.7.4
