Simplifies allocation by using a flexible arraay member.

Added __counted_by for extra runtime analysis.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 v2: remove extra kfree to fix kernel test bot.
 drivers/thunderbolt/path.c | 28 +++++++---------------------
 drivers/thunderbolt/tb.h   |  3 ++-
 2 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/drivers/thunderbolt/path.c b/drivers/thunderbolt/path.c
index 22fb4a1e1acd..8713ea0f47c1 100644
--- a/drivers/thunderbolt/path.c
+++ b/drivers/thunderbolt/path.c
@@ -150,22 +150,17 @@ struct tb_path *tb_path_discover(struct tb_port *src, int src_hopid,
 		num_hops++;
 	}

-	path = kzalloc_obj(*path);
+	path = kzalloc_flex(*path, hops, num_hops);
 	if (!path)
 		return NULL;

+	path->path_length = num_hops;
+
 	path->name = name;
 	path->tb = src->sw->tb;
-	path->path_length = num_hops;
 	path->activated = true;
 	path->alloc_hopid = alloc_hopid;

-	path->hops = kzalloc_objs(*path->hops, num_hops);
-	if (!path->hops) {
-		kfree(path);
-		return NULL;
-	}
-
 	tb_dbg(path->tb, "discovering %s path starting from %llx:%u\n",
 	       path->name, tb_route(src->sw), src->port);

@@ -245,10 +240,6 @@ struct tb_path *tb_path_alloc(struct tb *tb, struct tb_port *src, int src_hopid,
 	size_t num_hops;
 	int i, ret;

-	path = kzalloc_obj(*path);
-	if (!path)
-		return NULL;
-
 	first_port = last_port = NULL;
 	i = 0;
 	tb_for_each_port_on_path(src, dst, in_port) {
@@ -259,20 +250,17 @@ struct tb_path *tb_path_alloc(struct tb *tb, struct tb_port *src, int src_hopid,
 	}

 	/* Check that src and dst are reachable */
-	if (first_port != src || last_port != dst) {
-		kfree(path);
+	if (first_port != src || last_port != dst)
 		return NULL;
-	}

 	/* Each hop takes two ports */
 	num_hops = i / 2;

-	path->hops = kzalloc_objs(*path->hops, num_hops);
-	if (!path->hops) {
-		kfree(path);
+	path = kzalloc_flex(*path, hops, num_hops);
+	if (!path)
 		return NULL;
-	}

+	path->path_length = num_hops;
 	path->alloc_hopid = true;

 	in_hopid = src_hopid;
@@ -339,7 +327,6 @@ struct tb_path *tb_path_alloc(struct tb *tb, struct tb_port *src, int src_hopid,
 	}

 	path->tb = tb;
-	path->path_length = num_hops;
 	path->name = name;

 	return path;
@@ -372,7 +359,6 @@ void tb_path_free(struct tb_path *path)
 		}
 	}

-	kfree(path->hops);
 	kfree(path);
 }

diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index e96474f17067..4e66b53860dd 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -440,9 +440,10 @@ struct tb_path {
 	bool drop_packages;
 	bool activated;
 	bool clear_fc;
-	struct tb_path_hop *hops;
 	int path_length;
 	bool alloc_hopid;
+
+	struct tb_path_hop hops[] __counted_by(path_length);
 };

 /* HopIDs 0-7 are reserved by the Thunderbolt protocol */
--
2.53.0

On Mon, Mar 16, 2026 at 11:21:12AM -0700, Rosen Penev wrote:
> diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
> index e96474f17067..4e66b53860dd 100644
> --- a/drivers/thunderbolt/tb.h
> +++ b/drivers/thunderbolt/tb.h
> @@ -440,9 +440,10 @@ struct tb_path {
>  	bool drop_packages;
>  	bool activated;
>  	bool clear_fc;
> -	struct tb_path_hop *hops;
>  	int path_length;
>  	bool alloc_hopid;
> +
> +	struct tb_path_hop hops[] __counted_by(path_length);

Please update the kernel-doc too. Other than that this looks good.