[PATCH net v2] net: airoha: Fix schedule while atomic in airoha_ppe_deinit()

[Lorenzo Bianconi]

airoha_ppe_deinit() runs airoha_npu_ppe_deinit() in atomic context.
airoha_npu_ppe_deinit routine allocates ppe_data buffer with GFP_KERNEL
flag. Rely on rcu_replace_pointer in airoha_ppe_deinit routine in order
to fix schedule while atomic issue in airoha_npu_ppe_deinit() since we
do not need atomic context there.

Fixes: 00a7678310fe3 ("net: airoha: Introduce flowtable offload support")
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
Changes in v2:
- Update commit log.
- Link to v1: https://lore.kernel.org/r/20251223-airoha-fw-ethtool-v1-1-1dbd1568c585@kernel.org
---
 drivers/net/ethernet/airoha/airoha_ppe.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_ppe.c b/drivers/net/ethernet/airoha/airoha_ppe.c
index 0caabb0c3aa06948e46ad087c50eba5babc81994..2221bafaf7c9fed73dcf8d30ff3b1c5eecc463d4 100644
--- a/drivers/net/ethernet/airoha/airoha_ppe.c
+++ b/drivers/net/ethernet/airoha/airoha_ppe.c
@@ -1547,13 +1547,16 @@ void airoha_ppe_deinit(struct airoha_eth *eth)
 {
 	struct airoha_npu *npu;
 
-	rcu_read_lock();
-	npu = rcu_dereference(eth->npu);
+	mutex_lock(&flow_offload_mutex);
+
+	npu = rcu_replace_pointer(eth->npu, NULL,
+				  lockdep_is_held(&flow_offload_mutex));
 	if (npu) {
 		npu->ops.ppe_deinit(npu);
 		airoha_npu_put(npu);
 	}
-	rcu_read_unlock();
+
+	mutex_unlock(&flow_offload_mutex);
 
 	rhashtable_destroy(&eth->ppe->l2_flows);
 	rhashtable_destroy(&eth->flow_table);

---
base-commit: c303e8b86d9dbd6868f5216272973292f7f3b7f1
change-id: 20251223-airoha-fw-ethtool-21f54b02c98b

Best regards,
-- 
Lorenzo Bianconi <lorenzo at kernel.org>