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rpc: remove the existing socket file when application starts

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Currently if the application exits with some error (i.e., core
dump), the socket file is not removed. So that at next time the
RPC method can not enabled unless user manually removes the
socket file. The error of failing to start RPC is not that
obvious.

This patch introduces a lock for the reuse socket to properly
detect the only usage and handles the above error case particularly.

Refer to https://gavv.github.io/blog/unix-socket-reuse/ for the
details.

For the concern of the sockect file can be shared from different
applications, in the spdk_app_opts struct, it offers a parameter
to assign a specific socket file per application.

Change-Id: Ie2ef6af9207c468279cba5efd173fd06579ccdc7
Signed-off-by: GangCao <gang.cao@intel.com>
Reviewed-on: https://review.gerrithub.io/396089
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
This commit is contained in:
GangCao 2018-01-23 18:52:44 -05:00 committed by Jim Harris
parent 981607175b
commit dbeed703c2
1 changed files with 40 additions and 2 deletions
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42
lib/rpc/rpc.c
View File

@ -31,6 +31,8 @@
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/file.h>
#include "spdk/stdinc.h"
#include "spdk/queue.h"
@ -42,6 +44,8 @@
#define RPC_DEFAULT_PORT "5260"
static struct sockaddr_un g_rpc_listen_addr_unix = {};
static char g_rpc_lock_path[sizeof(g_rpc_listen_addr_unix.sun_path) + sizeof(".lock") + 1];
static int g_rpc_lock_fd = -1;
static struct spdk_jsonrpc_server *g_jsonrpc_server = NULL;
@ -93,15 +97,39 @@ spdk_rpc_listen(const char *listen_addr)
return -1;
}
if (access(g_rpc_listen_addr_unix.sun_path, F_OK) == 0) {
SPDK_ERRLOG("RPC Unix domain socket path already exists.\n");
snprintf(g_rpc_lock_path, sizeof(g_rpc_lock_path), "%s.lock",
g_rpc_listen_addr_unix.sun_path);
g_rpc_lock_fd = open(g_rpc_lock_path, O_RDONLY | O_CREAT, 0600);
if (g_rpc_lock_fd == -1) {
SPDK_ERRLOG("Cannot open lock file %s: %s\n",
g_rpc_lock_path, spdk_strerror(errno));
return -1;
}
rc = flock(g_rpc_lock_fd, LOCK_EX | LOCK_NB);
if (rc != 0) {
SPDK_ERRLOG("RPC Unix domain socket path %s in use. Specify another.\n",
g_rpc_listen_addr_unix.sun_path);
return -1;
}
/*
* Since we acquired the lock, it is safe to delete the Unix socket file
* if it still exists from a previous process.
*/
unlink(g_rpc_listen_addr_unix.sun_path);
g_jsonrpc_server = spdk_jsonrpc_server_listen(AF_UNIX, 0,
(struct sockaddr *)&g_rpc_listen_addr_unix,
sizeof(g_rpc_listen_addr_unix),
spdk_jsonrpc_handler);
if (g_jsonrpc_server == NULL) {
close(g_rpc_lock_fd);
g_rpc_lock_fd = -1;
unlink(g_rpc_lock_path);
g_rpc_lock_path[0] = '\0';
}
} else {
char *tmp;
char *host, *port;
@ -183,6 +211,16 @@ spdk_rpc_close(void)
spdk_jsonrpc_server_shutdown(g_jsonrpc_server);
g_jsonrpc_server = NULL;
if (g_rpc_lock_fd != -1) {
close(g_rpc_lock_fd);
g_rpc_lock_fd = -1;
}
if (g_rpc_lock_path[0]) {
unlink(g_rpc_lock_path);
g_rpc_lock_path[0] = '\0';
}
}
}