snull: use napi_schedule_prep() to prevent packet loss

By using napi_schedule_prep() and __napi_schedule(), ensure NAPI polls
are scheduled before disabling interrupts. This prevents dropped polls
and ensures rx_int_enabled is properly updated, fixing 100% packet loss
during state changes.

Authored-by: Leon <lzq.hdu@gmail.com>
Signed-off-by: Iman Seyed <ImanDevel@gmail.com>

snull/snull.c

@@ -428,9 +428,9 @@ static void snull_napi_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 	/* retrieve statusword: real netdevices use I/O instructions */
 	statusword = priv->status;
 	priv->status = 0;
-	if (statusword & SNULL_RX_INTR) {
+	if (statusword & SNULL_RX_INTR && napi_schedule_prep(&priv->napi)) {
 		snull_rx_ints(dev, 0);  /* Disable further interrupts */
-		napi_schedule(&priv->napi);
+		__napi_schedule(&priv->napi);
 	}
 	if (statusword & SNULL_TX_INTR) {
         	/* a transmission is over: free the skb */