lib/vhost: use contructor to initalize g_dpdk_sem

Using contructor/destructor to handle g_dpdk_sem will
help later in the series when splitting vhost fini
between vhost.c and virtio abstraction.

Otherwise multiple callbacks would be needed during vhost fini.
Ex. spdk_vhost_fini -> vhost_user_fini to stop the sessions ->
-> back to spdk_vhost_fini to remove vhost devices ->
-> vhost_user_fini to destroy the g_dpdk_sem

g_dpdk_sem will only be used from rte_vhost_user.c.
Until all references are moved, it is placed in vhost_internal.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Change-Id: I0505b906621f0eb0cb1226f96a3b6cf49f66778f
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/11055
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>

lib/vhost/rte_vhost_user.c

@@ -47,6 +47,22 @@
 #include "spdk_internal/vhost_user.h"
 
 char g_vhost_user_dev_dirname[PATH_MAX] = "";
+sem_t g_dpdk_sem;
+
+static void __attribute__((constructor))
+_vhost_user_sem_init(void)
+{
+	if (sem_init(&g_dpdk_sem, 0, 0) != 0) {
+		SPDK_ERRLOG("Failed to initialize semaphore for rte_vhost pthread.\n");
+		abort();
+	}
+}
+
+static void __attribute__((destructor))
+_vhost_user_sem_destroy(void)
+{
+	sem_destroy(&g_dpdk_sem);
+}
 
 static inline void
 vhost_session_mem_region_calc(uint64_t *previous_start, uint64_t *start, uint64_t *end,

lib/vhost/vhost.c

@@ -51,13 +51,6 @@ static struct spdk_thread *g_vhost_init_thread;
 
 static spdk_vhost_fini_cb g_fini_cpl_cb;
 
-/**
- * DPDK calls our callbacks synchronously but the work those callbacks
- * perform needs to be async. Luckily, all DPDK callbacks are called on
- * a DPDK-internal pthread, so we'll just wait on a semaphore in there.
- */
-static sem_t g_dpdk_sem;
-
 /** Return code for the current DPDK callback */
 static int g_dpdk_response;
 
@@ -1524,8 +1517,8 @@ spdk_vhost_init(spdk_vhost_init_cb init_cb)
 	if (g_vhost_user_dev_dirname[0] == '\0') {
 		if (getcwd(g_vhost_user_dev_dirname, sizeof(g_vhost_user_dev_dirname) - 1) == NULL) {
 			SPDK_ERRLOG("getcwd failed (%d): %s\n", errno, spdk_strerror(errno));
-			ret = -1;
-			goto out;
+			init_cb(-1);
+			return;
 		}
 
 		len = strlen(g_vhost_user_dev_dirname);
@@ -1535,18 +1528,10 @@ spdk_vhost_init(spdk_vhost_init_cb init_cb)
 		}
 	}
 
-	ret = sem_init(&g_dpdk_sem, 0, 0);
-	if (ret != 0) {
-		SPDK_ERRLOG("Failed to initialize semaphore for rte_vhost pthread.\n");
-		ret = -1;
-		goto out;
-	}
-
 	spdk_cpuset_zero(&g_vhost_core_mask);
 	SPDK_ENV_FOREACH_CORE(i) {
 		spdk_cpuset_set_cpu(&g_vhost_core_mask, i, true);
 	}
-out:
 	init_cb(ret);
 }
 
@@ -1565,9 +1550,6 @@ vhost_fini(void *arg1)
 	}
 	spdk_vhost_unlock();
 
-	/* All devices are removed now. */
-	sem_destroy(&g_dpdk_sem);
-
 	g_fini_cpl_cb();
 }
 

lib/vhost/vhost_internal.h

@@ -47,6 +47,13 @@
 
 extern bool g_packed_ring_recovery;
 
+/**
+ * DPDK calls our callbacks synchronously but the work those callbacks
+ * perform needs to be async. Luckily, all DPDK callbacks are called on
+ * a DPDK-internal pthread, so we'll just wait on a semaphore in there.
+ */
+extern sem_t g_dpdk_sem;
+
 #define SPDK_VHOST_MAX_VQUEUES	256
 #define SPDK_VHOST_MAX_VQ_SIZE	1024