From 2fae1bde426abd063847c10021eae7bafdc63c3d Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Wed, 5 Jun 2019 10:57:10 +0200
Subject: [PATCH] account/usbwallet: abort usb enumeration after failures

---
 accounts/usbwallet/hub.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/accounts/usbwallet/hub.go b/accounts/usbwallet/hub.go
index 8f34d63e8a..23be98a084 100644
--- a/accounts/usbwallet/hub.go
+++ b/accounts/usbwallet/hub.go
@@ -20,6 +20,7 @@ import (
 	"errors"
 	"runtime"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -64,6 +65,7 @@ type Hub struct {
 	// TODO(karalabe): remove if hotplug lands on Windows
 	commsPend int        // Number of operations blocking enumeration
 	commsLock sync.Mutex // Lock protecting the pending counter and enumeration
+	enumFails uint32     // Number of times enumeration has failed
 }
 
 // NewLedgerHub creates a new hardware wallet manager for Ledger devices.
@@ -138,6 +140,10 @@ func (hub *Hub) refreshWallets() {
 	if elapsed < refreshThrottling {
 		return
 	}
+	// If USB enumeration is continually failing, don't keep trying indefinitely
+	if atomic.LoadUint32(&hub.enumFails) > 2 {
+		return
+	}
 	// Retrieve the current list of USB wallet devices
 	var devices []usb.DeviceInfo
 
@@ -156,13 +162,17 @@ func (hub *Hub) refreshWallets() {
 	}
 	infos, err := usb.Enumerate(hub.vendorID, 0)
 	if err != nil {
+		failcount := atomic.AddUint32(&hub.enumFails, 1)
 		if runtime.GOOS == "linux" {
 			// See rationale before the enumeration why this is needed and only on Linux.
 			hub.commsLock.Unlock()
 		}
-		log.Error("error enumerating USB enumeration: ", "code", err)
+		log.Error("Failed to enumerate USB devices", "hub", hub.scheme,
+			"vendor", hub.vendorID, "failcount", failcount, "err", err)
 		return
 	}
+	atomic.StoreUint32(&hub.enumFails, 0)
+
 	for _, info := range infos {
 		for _, id := range hub.productIDs {
 			// Windows and Macos use UsageID matching, Linux uses Interface matching