[dpdk-dev] [PATCH v5 4/6] eal: lock IPC directory on init and send

[Anatoly Burakov]

When sending IPC messages, prevent new sockets from initializing.

Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---

Notes:
    v5: removed init files introduced in v4
    
    v4: fixed resource leaks and added support for init files
        introduced in v4 series

 lib/librte_eal/common/eal_common_proc.c | 59 +++++++++++++++++++++++++++++++--
 1 file changed, 56 insertions(+), 3 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_proc.c 
b/lib/librte_eal/common/eal_common_proc.c
index 9587211..c6fef75 100644
--- a/lib/librte_eal/common/eal_common_proc.c
+++ b/lib/librte_eal/common/eal_common_proc.c
@@ -13,6 +13,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/file.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -360,6 +361,7 @@ rte_mp_channel_init(void)
 {
        char thread_name[RTE_MAX_THREAD_NAME_LEN];
        char path[PATH_MAX];
+       int dir_fd;
        pthread_t tid;
 
        /* create filter path */
@@ -370,19 +372,38 @@ rte_mp_channel_init(void)
        create_socket_path("*", path, sizeof(path));
        snprintf(mp_dir_path, sizeof(mp_dir_path), "%s", dirname(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;
        }
@@ -390,6 +411,11 @@ 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;
 }
 
@@ -465,7 +491,7 @@ 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;
 
@@ -487,6 +513,17 @@ 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];
 
@@ -498,7 +535,10 @@ mp_send(struct rte_mp_msg *msg, const char *peer, int type)
                if (send_msg(path, msg, type) < 0)
                        ret = -1;
        }
+       /* unlock the dir */
+       flock(dir_fd, LOCK_UN);
 
+       /* dir_fd automatically closed on closedir */
        closedir(mp_dir);
        return ret;
 }
@@ -619,7 +659,7 @@ 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;
@@ -655,6 +695,16 @@ rte_mp_request(struct rte_mp_msg *req, struct rte_mp_reply 
*reply,
                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))) {
                char path[PATH_MAX];
 
@@ -667,7 +717,10 @@ 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