[PATCH] wifi: mt76: Fix missing barrier after initialization check in ath9k_wmi_event_tasklet()

[Thomas Fourier <fourier.thomas@gmail.com>]

The write memory barrier in ath9k_htc_probe_device() before writing to
priv->initialized, so it seems like one is also needed after reading it,
but seems like there is none after reading priv->initialized.

Add a read barrier after reading the priv->initialized flag to prevent
reordering of reads.

Fixes: 8b3046abc99e ("ath9k_htc: fix NULL pointer dereference at ath9k_htc_tx_get_packet()")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
---
 drivers/net/wireless/ath/ath9k/wmi.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c
index 284e8c13b043..1e28599a6146 100644
--- a/drivers/net/wireless/ath/ath9k/wmi.c
+++ b/drivers/net/wireless/ath/ath9k/wmi.c
@@ -160,6 +160,11 @@ void ath9k_wmi_event_tasklet(struct tasklet_struct *t)
 			kfree_skb(skb);
 			continue;
 		}
+		/*
+		 * Make sure ath9k_htc_probe_device() initialization is
+		 * committed to memory before processing skb.
+		 */
+		smp_rmb();
 
 		hdr = (struct wmi_cmd_hdr *) skb->data;
 		cmd_id = be16_to_cpu(hdr->command_id);
-- 
2.43.0