vhost: change vdev global array to a linked list

Drop max vhost initiators limitation in SPDK (64).
We're still limited by rte_vhost limits, but
they're set to 1024 at the moment.

Change-Id: Ia1ad25665d6e798bc22709cdd43b72d60f1f4cf0
Signed-off-by: Slawomir Mrozowicz <slawomirx.mrozowicz@intel.com>
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/389811
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

lib/vhost/vhost.c

@@ -47,8 +47,6 @@ static uint32_t *g_num_ctrlrs;
 /* Path to folder where character device will be created. Can be set by user. */
 static char dev_dirname[PATH_MAX] = "";
 
-#define MAX_VHOST_DEVICES	64
-
 struct spdk_vhost_dev_event_ctx {
 	/** Pointer to the controller obtained before enqueuing the event */
 	struct spdk_vhost_dev *vdev;
@@ -83,7 +81,8 @@ const struct vhost_device_ops g_spdk_vhost_ops = {
 	.destroy_connection = destroy_connection,
 };
 
-static struct spdk_vhost_dev *g_spdk_vhost_devices[MAX_VHOST_DEVICES];
+static TAILQ_HEAD(, spdk_vhost_dev) g_spdk_vhost_devices = TAILQ_HEAD_INITIALIZER(
+			g_spdk_vhost_devices);
 static pthread_mutex_t g_spdk_vhost_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 void *spdk_vhost_gpa_to_vva(struct spdk_vhost_dev *vdev, uint64_t addr)
@@ -473,12 +472,10 @@ spdk_vhost_dev_has_feature(struct spdk_vhost_dev *vdev, unsigned feature_id)
 static struct spdk_vhost_dev *
 spdk_vhost_dev_find_by_id(unsigned id)
 {
-	unsigned i;
 	struct spdk_vhost_dev *vdev;
 
-	for (i = 0; i < MAX_VHOST_DEVICES; i++) {
-		vdev = g_spdk_vhost_devices[i];
-		if (vdev && vdev->id == id) {
+	TAILQ_FOREACH(vdev, &g_spdk_vhost_devices, tailq) {
+		if (vdev->id == id) {
 			return vdev;
 		}
 	}
@@ -489,12 +486,10 @@ spdk_vhost_dev_find_by_id(unsigned id)
 static struct spdk_vhost_dev *
 spdk_vhost_dev_find_by_vid(int vid)
 {
-	unsigned i;
 	struct spdk_vhost_dev *vdev;
 
-	for (i = 0; i < MAX_VHOST_DEVICES; i++) {
-		vdev = g_spdk_vhost_devices[i];
-		if (vdev && vdev->vid == vid) {
+	TAILQ_FOREACH(vdev, &g_spdk_vhost_devices, tailq) {
+		if (vdev->vid == vid) {
 			return vdev;
 		}
 	}
@@ -562,20 +557,16 @@ spdk_vhost_free_reactor(uint32_t lcore)
 struct spdk_vhost_dev *
 spdk_vhost_dev_find(const char *ctrlr_name)
 {
-	unsigned i;
+	struct spdk_vhost_dev *vdev;
 	size_t dev_dirname_len = strlen(dev_dirname);
 
 	if (strncmp(ctrlr_name, dev_dirname, dev_dirname_len) == 0) {
 		ctrlr_name += dev_dirname_len;
 	}
 
-	for (i = 0; i < MAX_VHOST_DEVICES; i++) {
-		if (g_spdk_vhost_devices[i] == NULL) {
-			continue;
-		}
-
-		if (strcmp(g_spdk_vhost_devices[i]->name, ctrlr_name) == 0) {
-			return g_spdk_vhost_devices[i];
+	TAILQ_FOREACH(vdev, &g_spdk_vhost_devices, tailq) {
+		if (strcmp(vdev->name, ctrlr_name) == 0) {
+			return vdev;
 		}
 	}
 
@@ -615,7 +606,7 @@ int
 spdk_vhost_dev_register(struct spdk_vhost_dev *vdev, const char *name, const char *mask_str,
 			const struct spdk_vhost_dev_backend *backend)
 {
-	unsigned ctrlr_num;
+	static unsigned ctrlr_num;
 	char path[PATH_MAX];
 	struct stat file_stat;
 	struct spdk_cpuset *cpumask;
@@ -623,6 +614,16 @@ spdk_vhost_dev_register(struct spdk_vhost_dev *vdev, const char *name, const cha
 
 	assert(vdev);
 
+	/* We expect devices inside g_spdk_vhost_devices to be sorted in ascending
+	 * order in regard of vdev->id. For now we always set vdev->id = ctrlr_num++
+	 * and append each vdev to the very end of g_spdk_vhost_devices list.
+	 * This is required for foreach vhost events to work.
+	 */
+	if (ctrlr_num == UINT_MAX) {
+		assert(false);
+		return -EINVAL;
+	}
+
 	if (name == NULL) {
 		SPDK_ERRLOG("Can't register controller with no name\n");
 		return -EINVAL;
@@ -647,18 +648,6 @@ spdk_vhost_dev_register(struct spdk_vhost_dev *vdev, const char *name, const cha
 		goto out;
 	}
 
-	for (ctrlr_num = 0; ctrlr_num < MAX_VHOST_DEVICES; ctrlr_num++) {
-		if (g_spdk_vhost_devices[ctrlr_num] == NULL) {
-			break;
-		}
-	}
-
-	if (ctrlr_num == MAX_VHOST_DEVICES) {
-		SPDK_ERRLOG("Max controllers reached (%d).\n", MAX_VHOST_DEVICES);
-		rc = -ENOSPC;
-		goto out;
-	}
-
 	if (snprintf(path, sizeof(path), "%s%s", dev_dirname, name) >= (int)sizeof(path)) {
 		SPDK_ERRLOG("Resulting socket path for controller %s is too long: %s%s\n", name, dev_dirname,
 			    name);
@@ -707,7 +696,7 @@ spdk_vhost_dev_register(struct spdk_vhost_dev *vdev, const char *name, const cha
 
 	vdev->name = strdup(name);
 	vdev->path = strdup(path);
-	vdev->id = ctrlr_num;
+	vdev->id = ctrlr_num++;
 	vdev->vid = -1;
 	vdev->lcore = -1;
 	vdev->cpumask = cpumask;
@@ -720,7 +709,7 @@ spdk_vhost_dev_register(struct spdk_vhost_dev *vdev, const char *name, const cha
 	vdev->stats_check_interval = SPDK_VHOST_DEV_STATS_CHECK_INTERVAL_MS * spdk_get_ticks_hz() /
 				     1000UL;
 
-	g_spdk_vhost_devices[ctrlr_num] = vdev;
+	TAILQ_INSERT_TAIL(&g_spdk_vhost_devices, vdev, tailq);
 
 	if (rte_vhost_driver_start(path) != 0) {
 		SPDK_ERRLOG("Failed to start vhost driver for controller %s (%d): %s\n", name, errno,
@@ -757,16 +746,18 @@ spdk_vhost_dev_unregister(struct spdk_vhost_dev *vdev)
 	free(vdev->name);
 	free(vdev->path);
 	spdk_cpuset_free(vdev->cpumask);
-	g_spdk_vhost_devices[vdev->id] = NULL;
+	TAILQ_REMOVE(&g_spdk_vhost_devices, vdev, tailq);
 	return 0;
 }
 
 static struct spdk_vhost_dev *
-spdk_vhost_dev_next(int i)
+spdk_vhost_dev_next(unsigned i)
 {
-	for (i++; i < MAX_VHOST_DEVICES; i++) {
-		if (g_spdk_vhost_devices[i]) {
-			return g_spdk_vhost_devices[i];
+	struct spdk_vhost_dev *vdev;
+
+	TAILQ_FOREACH(vdev, &g_spdk_vhost_devices, tailq) {
+		if (vdev->id > i) {
+			return vdev;
 		}
 	}
 
@@ -854,7 +845,7 @@ spdk_vhost_event_async_fn(void *arg1, void *arg2)
 	free(ctx);
 }
 
-static void spdk_vhost_external_event_foreach_continue(int vdev_id,
+static void spdk_vhost_external_event_foreach_continue(struct spdk_vhost_dev *vdev,
 		spdk_vhost_event_fn fn, void *arg);
 
 static void
@@ -874,9 +865,14 @@ spdk_vhost_event_async_foreach_fn(void *arg1, void *arg2)
 	vdev = spdk_vhost_dev_find_by_id(ctx->vdev_id);
 	if (vdev == ctx->vdev) {
 		ctx->cb_fn(vdev, arg2);
+	} else {
+		/* ctx->vdev is probably a dangling pointer at this point.
+		 * It must have been removed in the meantime, so we just skip
+		 * it in our foreach chain. */
 	}
 
-	spdk_vhost_external_event_foreach_continue(ctx->vdev_id, ctx->cb_fn, arg2);
+	vdev = spdk_vhost_dev_next(ctx->vdev_id);
+	spdk_vhost_external_event_foreach_continue(vdev, ctx->cb_fn, arg2);
 	pthread_mutex_unlock(&g_spdk_vhost_mutex);
 
 	free(ctx);
@@ -1155,14 +1151,8 @@ static void *
 session_shutdown(void *arg)
 {
 	struct spdk_vhost_dev *vdev = NULL;
-	int i;
-
-	for (i = 0; i < MAX_VHOST_DEVICES; i++) {
-		vdev = g_spdk_vhost_devices[i];
-		if (vdev == NULL) {
-			continue;
-		}
 
+	TAILQ_FOREACH(vdev, &g_spdk_vhost_devices, tailq) {
 		rte_vhost_driver_unregister(vdev->path);
 		vdev->registered = false;
 	}
@@ -1260,11 +1250,9 @@ spdk_vhost_call_external_event(const char *ctrlr_name, spdk_vhost_event_fn fn, v
 }
 
 static void
-spdk_vhost_external_event_foreach_continue(int vdev_id, spdk_vhost_event_fn fn, void *arg)
+spdk_vhost_external_event_foreach_continue(struct spdk_vhost_dev *vdev,
+		spdk_vhost_event_fn fn, void *arg)
 {
-	struct spdk_vhost_dev *vdev;
-
-	vdev = spdk_vhost_dev_next(vdev_id);
 	if (vdev == NULL) {
 		fn(NULL, arg);
 		return;
@@ -1285,8 +1273,11 @@ spdk_vhost_external_event_foreach_continue(int vdev_id, spdk_vhost_event_fn fn,
 void
 spdk_vhost_call_external_event_foreach(spdk_vhost_event_fn fn, void *arg)
 {
+	struct spdk_vhost_dev *vdev;
+
 	pthread_mutex_lock(&g_spdk_vhost_mutex);
-	spdk_vhost_external_event_foreach_continue(-1, fn, arg);
+	vdev = TAILQ_FIRST(&g_spdk_vhost_devices);
+	spdk_vhost_external_event_foreach_continue(vdev, fn, arg);
 	pthread_mutex_unlock(&g_spdk_vhost_mutex);
 }
 

lib/vhost/vhost_internal.h

@@ -165,6 +165,8 @@ struct spdk_vhost_dev {
 	uint64_t negotiated_features;
 
 	struct spdk_vhost_virtqueue virtqueue[SPDK_VHOST_MAX_VQUEUES];
+
+	TAILQ_ENTRY(spdk_vhost_dev) tailq;
 };
 
 struct spdk_vhost_dev *spdk_vhost_dev_find(const char *ctrlr_name);

test/unit/lib/vhost/vhost.c/vhost_ut.c

@@ -228,7 +228,6 @@ create_controller_test(void)
 {
 	struct spdk_vhost_dev *vdev, *vdev2;
 	int ret;
-	unsigned ctrlr_num;
 	char long_name[PATH_MAX];
 	struct spdk_vhost_dev_backend backend;
 
@@ -257,22 +256,10 @@ create_controller_test(void)
 	vdev2 = alloc_vdev();
 	ret = spdk_vhost_dev_register(vdev2, "vdev_name_0", "0x1", &backend);
 	CU_ASSERT(ret != 0);
-
-	/* Create device when max number of devices is reached */
-	for (ctrlr_num = 0; ctrlr_num < MAX_VHOST_DEVICES; ctrlr_num ++) {
-		g_spdk_vhost_devices[ctrlr_num] = vdev;
-	}
-
-	ret = spdk_vhost_dev_register(vdev2, "vdev_name_1", "0x1", &backend);
-	CU_ASSERT(ret != 0);
 	free_vdev(vdev2);
 
 	spdk_vhost_dev_unregister(vdev);
 	free_vdev(vdev);
-
-	for (ctrlr_num = 0; ctrlr_num < MAX_VHOST_DEVICES; ctrlr_num++) {
-		g_spdk_vhost_devices[ctrlr_num] = NULL;
-	}
 }
 
 static void