[dpdk-dev] [PATCH v4 3/5] eal: prevent secondary process init while sending messages

Anatoly Burakov anatoly.burakov at intel.com
Fri Mar 2 16:14:10 CET 2018


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.

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
---

Notes:
    v4: fixed resource leaks and added support for init files
        introduced in v4 series
    
    v4: fix resource leaks, also lock when removing init file
    
    v3: no changes
    
    v2: no changes

 lib/librte_eal/common/eal_common_proc.c | 81 +++++++++++++++++++++++++++++++--
 1 file changed, 77 insertions(+), 4 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_proc.c b/lib/librte_eal/common/eal_common_proc.c
index 4d227fe..94672ba 100644
--- a/lib/librte_eal/common/eal_common_proc.c
+++ b/lib/librte_eal/common/eal_common_proc.c
@@ -436,10 +436,30 @@ int
 rte_mp_channel_set_ready(void)
 {
 	char path[PATH_MAX] = {0};
+	int dir_fd, ret;
+
+	/* 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;
+	}
 
 	create_initfile_path(process_peer_name, path, PATH_MAX);
 
-	return unlink(path);
+	ret = unlink(path);
+
+	flock(dir_fd, LOCK_UN);
+	close(dir_fd);
+
+	return ret;
 }
 
 int
@@ -447,6 +467,7 @@ 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_*",
@@ -456,19 +477,38 @@ 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",
 			strerror(errno));
 		close(mp_fd);
+		close(dir_fd);
 		mp_fd = -1;
 		return -1;
 	}
@@ -476,6 +516,11 @@ 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;
 }
 
@@ -551,7 +596,7 @@ send_msg(const char *dst_path, struct rte_mp_msg *msg, int type)
 static int
 mp_send(struct rte_mp_msg *msg, const char *peer, int type)
 {
-	int ret = 0;
+	int dir_fd, ret = 0;
 	DIR *mp_dir;
 	struct dirent *ent;
 
@@ -573,6 +618,17 @@ mp_send(struct rte_mp_msg *msg, const char *peer, int type)
 		rte_errno = errno;
 		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;
@@ -592,7 +648,10 @@ mp_send(struct rte_mp_msg *msg, const char *peer, int type)
 		else if (ready > 0)
 			ret = send_msg(path, msg, type);
 	}
+	/* unlock the dir */
+	flock(dir_fd, LOCK_UN);
 
+	/* dir_fd automatically closed on closedir */
 	closedir(mp_dir);
 	return ret;
 }
@@ -713,7 +772,7 @@ int __rte_experimental
 rte_mp_request(struct rte_mp_msg *req, struct rte_mp_reply *reply,
 		const struct timespec *ts)
 {
-	int ret = 0;
+	int dir_fd, ret = 0;
 	DIR *mp_dir;
 	struct dirent *ent;
 	struct timeval now;
@@ -748,6 +807,17 @@ rte_mp_request(struct rte_mp_msg *req, struct rte_mp_reply *reply,
 		rte_errno = errno;
 		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);
+		closedir(mp_dir);
+		rte_errno = errno;
+		return -1;
+	}
+
 	while ((ent = readdir(mp_dir))) {
 		const char *peer_name;
 		char path[PATH_MAX];
@@ -772,7 +842,10 @@ 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);
 
+	/* dir_fd automatically closed on closedir */
 	closedir(mp_dir);
 	return ret;
 }
-- 
2.7.4


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