diff mbox series

[mlx5-vhost,1/7] net/mlx5: Support throttled commands from async API

Message ID 20240802072039.267446-2-dtatulea@nvidia.com (mailing list archive)
State Awaiting Upstream
Delegated to: Netdev Maintainers
Headers show
Series vdpa/mlx5: Parallelize device suspend/resume | expand

Commit Message

Dragos Tatulea Aug. 2, 2024, 7:20 a.m. UTC 
Currently, commands that qualify as throttled can't be used via the
async API. That's due to the fact that the throttle semaphore can sleep
but the async API can't.

This patch allows throttling in the async API by using the tentative
variant of the semaphore and upon failure (semaphore at 0) returns EBUSY
to signal to the caller that they need to wait for the completion of
previously issued commands.

Furthermore, make sure that the semaphore is released in the callback.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Cc: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/cmd.c | 21 ++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
index 20768ef2e9d2..f69c977c1569 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
@@ -1882,10 +1882,12 @@  static int cmd_exec(struct mlx5_core_dev *dev, void *in, int in_size, void *out,
 
 	throttle_op = mlx5_cmd_is_throttle_opcode(opcode);
 	if (throttle_op) {
-		/* atomic context may not sleep */
-		if (callback)
-			return -EINVAL;
-		down(&dev->cmd.vars.throttle_sem);
+		if (callback) {
+			if (down_trylock(&dev->cmd.vars.throttle_sem))
+				return -EBUSY;
+		} else {
+			down(&dev->cmd.vars.throttle_sem);
+		}
 	}
 
 	pages_queue = is_manage_pages(in);
@@ -2091,10 +2093,19 @@  static void mlx5_cmd_exec_cb_handler(int status, void *_work)
 {
 	struct mlx5_async_work *work = _work;
 	struct mlx5_async_ctx *ctx;
+	struct mlx5_core_dev *dev;
+	u16 opcode;
 
 	ctx = work->ctx;
-	status = cmd_status_err(ctx->dev, status, work->opcode, work->op_mod, work->out);
+	dev = ctx->dev;
+	opcode = work->opcode;
+	status = cmd_status_err(dev, status, work->opcode, work->op_mod, work->out);
 	work->user_callback(status, work);
+	/* Can't access "work" from this point on. It could have been freed in
+	 * the callback.
+	 */
+	if (mlx5_cmd_is_throttle_opcode(opcode))
+		up(&dev->cmd.vars.throttle_sem);
 	if (atomic_dec_and_test(&ctx->num_inflight))
 		complete(&ctx->inflight_done);
 }