[PATCH net v4 04/15] xsk: freeze deferred pool teardown during system sleep

[James Hilliard <james.hilliard1@gmail.com>]

Pool destruction calls the driver under RTNL from system_wq. That queue
is not frozen during system sleep, so ndo_bpf() can run after the device
suspend callback has gated its clocks or after the noirq phase.

Use the freezable workqueue for deferred pool release. Work already
running completes before device suspend, and newly queued destruction
waits until device resume. The pool, UMEM and netdev references remain
owned by the work until then. This does not replace driver error
handling after a failed resume.

Fixes: 1c1efc2af158 ("xsk: Create and free buffer pool independently from umem")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 net/xdp/xsk_buff_pool.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index 9d2d94f1fb75..c58f56f24a9c 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -337,7 +337,10 @@ bool xp_put_pool(struct xsk_buff_pool *pool)
 
 	if (refcount_dec_and_test(&pool->users)) {
 		INIT_WORK(&pool->work, xp_release_deferred);
-		schedule_work(&pool->work);
+		/* Teardown calls ndo_bpf(), which may need powered hardware.
+		 * RTNL alone does not exclude the device's system PM callbacks.
+		 */
+		queue_work(system_freezable_wq, &pool->work);
 		return true;
 	}
 

-- 
2.53.0