[PATCH v3 01/15] NTB: ntb_transport: Remove the device debugfs directory

[Koichiro Den <den@valinux.co.jp>]

ntb_transport_free() removes QP debugfs directories but leaves the
device directory. On rebind, debugfs_create_dir() fails with -EEXIST
and QP statistics files are not recreated. Module unload masks this
by removing the entire debugfs tree.

To reproduce:

  # ls /sys/kernel/debug/ntb_transport/0001:10:00.0/
  qp0
  # echo 0001:10:00.0 > /sys/bus/ntb/drivers/ntb_transport/unbind
  # ls /sys/kernel/debug/ntb_transport/
  0001:10:00.0   <-- should not remain
  # echo 0001:10:00.0 > /sys/bus/ntb/drivers/ntb_transport/bind

  .. and then dmesg shows:
  debugfs: '0001:10:00.0' already exists in 'ntb_transport'

  # ls /sys/kernel/debug/ntb_transport/0001:10:00.0/
  (nothing)      <-- should be 'qp0'

Remove the device debugfs tree on teardown and probe failure.

Verified that unbind removes the directory and rebind recreates qp0.

Fixes: c8650fd03d32 ("NTB: Fix transport stats for multiple devices")
Cc: stable@vger.kernel.org
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
Changes in v3:
  - Add Reviewed-by tags. No code changes.

 drivers/ntb/ntb_transport.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index f9caa1a653c5..3389d6ca9ebd 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1382,6 +1382,7 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
 err3:
 	ntb_clear_ctx(ndev);
 err2:
+	debugfs_remove_recursive(nt->debugfs_node_dir);
 	kfree(nt->qp_vec);
 err1:
 	while (i--) {
@@ -1401,6 +1402,8 @@ static void ntb_transport_free(struct ntb_client *self, struct ntb_dev *ndev)
 	u64 qp_bitmap_alloc;
 	int i;
 
+	debugfs_remove_recursive(nt->debugfs_node_dir);
+
 	ntb_transport_link_cleanup(nt);
 	cancel_work_sync(&nt->link_cleanup);
 	cancel_delayed_work_sync(&nt->link_work);
@@ -1412,7 +1415,6 @@ static void ntb_transport_free(struct ntb_client *self, struct ntb_dev *ndev)
 		qp = &nt->qp_vec[i];
 		if (qp_bitmap_alloc & BIT_ULL(i))
 			ntb_transport_free_queue(qp);
-		debugfs_remove_recursive(qp->debugfs_dir);
 	}
 
 	ntb_link_disable(ndev);
-- 
2.51.0