forcedeth: allow to silence "TX timeout" debug messages

This adds a new module parameter "debug_tx_timeout" to silence most
debug messages in case of TX timeout. These messages don't provide a
signal/noise ratio high enough for production systems and, with ~30kB
logged each time, they tend to add to a cascade effect if the system
is already under stress (memory pressure, disk, etc.).

By default, the parameter is clear, meaning that only a single warning
will be reported.
Signed-off-by: NDavid Decotigny <david.decotigny@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/nvidia/forcedeth.c

@@ -891,6 +891,11 @@ enum {
 };
 static int dma_64bit = NV_DMA_64BIT_ENABLED;
 
+/*
+ * Debug output control for tx_timeout
+ */
+static bool debug_tx_timeout = false;
+
 /*
  * Crossover Detection
  * Realtek 8201 phy + some OEM boards do not work properly.
@@ -2477,20 +2482,23 @@ static void nv_tx_timeout(struct net_device *dev)
 	u32 status;
 	union ring_type put_tx;
 	int saved_tx_limit;
-	int i;
 
 	if (np->msi_flags & NV_MSI_X_ENABLED)
 		status = readl(base + NvRegMSIXIrqStatus) & NVREG_IRQSTAT_MASK;
 	else
 		status = readl(base + NvRegIrqStatus) & NVREG_IRQSTAT_MASK;
 
-	netdev_info(dev, "Got tx_timeout. irq: %08x\n", status);
+	netdev_warn(dev, "Got tx_timeout. irq status: %08x\n", status);
+
+	if (unlikely(debug_tx_timeout)) {
+		int i;
 
 		netdev_info(dev, "Ring at %lx\n", (unsigned long)np->ring_addr);
 		netdev_info(dev, "Dumping tx registers\n");
 		for (i = 0; i <= np->register_size; i += 32) {
 			netdev_info(dev,
-			    "%3x: %08x %08x %08x %08x %08x %08x %08x %08x\n",
+				    "%3x: %08x %08x %08x %08x "
+				    "%08x %08x %08x %08x\n",
 				    i,
 				    readl(base + i + 0), readl(base + i + 4),
 				    readl(base + i + 8), readl(base + i + 12),
@@ -2501,7 +2509,8 @@ static void nv_tx_timeout(struct net_device *dev)
 		for (i = 0; i < np->tx_ring_size; i += 4) {
 			if (!nv_optimized(np)) {
 				netdev_info(dev,
-				    "%03x: %08x %08x // %08x %08x // %08x %08x // %08x %08x\n",
+					    "%03x: %08x %08x // %08x %08x "
+					    "// %08x %08x // %08x %08x\n",
 					    i,
 					    le32_to_cpu(np->tx_ring.orig[i].buf),
 					    le32_to_cpu(np->tx_ring.orig[i].flaglen),
@@ -2513,7 +2522,10 @@ static void nv_tx_timeout(struct net_device *dev)
 					    le32_to_cpu(np->tx_ring.orig[i+3].flaglen));
 			} else {
 				netdev_info(dev,
-				    "%03x: %08x %08x %08x // %08x %08x %08x // %08x %08x %08x // %08x %08x %08x\n",
+					    "%03x: %08x %08x %08x "
+					    "// %08x %08x %08x "
+					    "// %08x %08x %08x "
+					    "// %08x %08x %08x\n",
 					    i,
 					    le32_to_cpu(np->tx_ring.ex[i].bufhigh),
 					    le32_to_cpu(np->tx_ring.ex[i].buflow),
@@ -2529,6 +2541,7 @@ static void nv_tx_timeout(struct net_device *dev)
 					    le32_to_cpu(np->tx_ring.ex[i+3].flaglen));
 			}
 		}
+	}
 
 	spin_lock_irq(&np->lock);
 
@@ -6157,6 +6170,9 @@ module_param(phy_cross, int, 0);
 MODULE_PARM_DESC(phy_cross, "Phy crossover detection for Realtek 8201 phy is enabled by setting to 1 and disabled by setting to 0.");
 module_param(phy_power_down, int, 0);
 MODULE_PARM_DESC(phy_power_down, "Power down phy and disable link when interface is down (1), or leave phy powered up (0).");
+module_param(debug_tx_timeout, bool, 0);
+MODULE_PARM_DESC(debug_tx_timeout,
+		 "Dump tx related registers and ring when tx_timeout happens");
 
 MODULE_AUTHOR("Manfred Spraul <manfred@colorfullife.com>");
 MODULE_DESCRIPTION("Reverse Engineered nForce ethernet driver");