wil6210: protect wil_vring_fini_tx in parallel to tx completions

napi_synchronize is called before releasing the vring, with the
assumption that setting txdata->enabled to 0 will prevent handling
of this vring in the next scheduled napi.
To guarantee this assumption, a memory barrier is added after disabling
the txdata.
In addition, as the ctx is zeroed in wil_tx_complete after this
descriptor is handled (protected by wmb), ctx needs to be checked
before releasing this descriptor in wil_vring_free.

Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

diff --git a/drivers/net/wireless/ath/wil6210/txrx.c b/drivers/net/wireless/ath/wil6210/txrx.c
index 3909af1..483e063 100644 (file)
--- a/drivers/net/wireless/ath/wil6210/txrx.c
+++ b/drivers/net/wireless/ath/wil6210/txrx.c
@@ -184,6 +184,13 @@ static void wil_vring_free(struct wil6210_priv *wil, struct vring *vring,
                                        &vring->va[vring->swtail].tx;
 
                        ctx = &vring->ctx[vring->swtail];
+                       if (!ctx) {
+                               wil_dbg_txrx(wil,
+                                            "ctx(%d) was already completed\n",
+                                            vring->swtail);
+                               vring->swtail = wil_vring_next_tail(vring);
+                               continue;
+                       }
                        *d = *_d;
                        wil_txdesc_unmap(dev, d, ctx);
                        if (ctx->skb)
@@ -975,6 +982,13 @@ void wil_vring_fini_tx(struct wil6210_priv *wil, int id)
        txdata->dot1x_open = false;
        txdata->enabled = 0; /* no Tx can be in progress or start anew */
        spin_unlock_bh(&txdata->lock);
+       /* napi_synchronize waits for completion of the current NAPI but will
+        * not prevent the next NAPI run.
+        * Add a memory barrier to guarantee that txdata->enabled is zeroed
+        * before napi_synchronize so that the next scheduled NAPI will not
+        * handle this vring
+        */
+       wmb();
        /* make sure NAPI won't touch this vring */
        if (test_bit(wil_status_napi_en, wil->status))
                napi_synchronize(&wil->napi_tx);