[PATCH net v2 01/14] net: pse-pd: size the notification kfifo after defaulting nr_lines

[Carlo Szelinsky <github@szelinsky.de>]

pse_controller_register() allocates the notification kfifo before it
turns nr_lines == 0 into 1, and kfifo_alloc() fails for a size below 2.
So a controller with nr_lines 0 or 1 cannot register. pse_regulator
(podl-pse-regulator) never sets nr_lines, so its probe has failed with
-EINVAL ever since the kfifo was added.

Apply the default first, and allocate at least two entries.

Triggered in QEMU (arm64) with a test-only PSE controller with
nr_lines 0: its probe failed with "failed to allocate kfifo
notifications". With this patch it registers.

Fixes: ffef61d6d273 ("net: pse-pd: Add support for budget evaluation strategies")
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Carlo Szelinsky <github@szelinsky.de>
---
 drivers/net/pse-pd/pse_core.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/pse-pd/pse_core.c b/drivers/net/pse-pd/pse_core.c
index a5e6d7b26b9f..c0573cbbba5b 100644
--- a/drivers/net/pse-pd/pse_core.c
+++ b/drivers/net/pse-pd/pse_core.c
@@ -1044,16 +1044,19 @@ int pse_controller_register(struct pse_controller_dev *pcdev)
 	mutex_init(&pcdev->lock);
 	INIT_LIST_HEAD(&pcdev->pse_control_head);
 	spin_lock_init(&pcdev->ntf_fifo_lock);
-	ret = kfifo_alloc(&pcdev->ntf_fifo, pcdev->nr_lines, GFP_KERNEL);
+
+	if (!pcdev->nr_lines)
+		pcdev->nr_lines = 1;
+
+	/* kfifo_alloc() rejects a size that rounds up to less than 2 */
+	ret = kfifo_alloc(&pcdev->ntf_fifo, max(pcdev->nr_lines, 2U),
+			  GFP_KERNEL);
 	if (ret) {
 		dev_err(pcdev->dev, "failed to allocate kfifo notifications\n");
 		return ret;
 	}
 	INIT_WORK(&pcdev->ntf_work, pse_send_ntf_worker);
 
-	if (!pcdev->nr_lines)
-		pcdev->nr_lines = 1;
-
 	if (!pcdev->ops->pi_get_admin_state ||
 	    !pcdev->ops->pi_get_pw_status) {
 		dev_err(pcdev->dev,
-- 
2.43.0