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nusb/usbd: attach spam protection for reset loops and flanky devices

When attach happens on a port within Attachdelay (3 seconds),
we count it as a repeated attach and if this happens
Attachcount (5) times in a row, we print an error and
refuse to attach the device.

Ori needs this as he has a usb hid device rgb led controller
in his computer that just gives read errors and causes
a continuous reset loop on the port, spamming the console.

--- a/sys/src/cmd/nusb/usbd/dat.h

+++ b/sys/src/cmd/nusb/usbd/dat.h

@@ -54,14 +54,14 @@

 	Pconfiged,

 	/* Delays, timeouts (ms) */

-	Spawndelay	= 250,		/* how often may we re-spawn a driver */

 	Resetdelay	= 20,		/* how much to wait after a reset */

 	Enabledelay	= 20,		/* how much to wait after an enable */

 	Powerdelay	= 100,		/* after powering up ports */

 	Pollms		= 250, 		/* port poll interval */

-	Chgdelay	= 100,		/* waiting for port become stable */

-	Chgtmout	= 1000,		/* ...but at most this much */

+	Attachdelay	= 3000,		/* attach considered repeated if within Attachdelay */

+	Attachcount	= 5,		/* maximum number of repeated attaches before giving up */

+

 	/*

 	 * device tab for embedded usb drivers.

 	 */

@@ -91,6 +91,8 @@

 {

 	int	state;		/* state of the device */

 	u32int	sts;		/* old port status */

+	ulong	atime;		/* time of last attach in milliseconds */

+	int	acount;		/* rapid attach counter */

 	uchar	removable;

 	uchar	pwrctl;

 	Dev	*dev;		/* attached device (if non-nil) */

--- a/sys/src/cmd/nusb/usbd/hub.c

+++ b/sys/src/cmd/nusb/usbd/hub.c

@@ -10,6 +10,7 @@

 static int nhubs;

 static int mustdump;

 static int pollms = Pollms;

+static ulong nowms;

 static char *dsname[] = { "disabled", "attached", "configed" };

@@ -358,6 +359,20 @@

 	d = h->dev;

 	pp = &h->port[p];

 	nd = nil;

+

+	/*

+	 * prevent repeated attaches in short succession as it is a indication

+	 * for a reset loop or a very flanky device.

+	 */

+	if(pp->acount && nowms - pp->atime >= Attachdelay)

+		pp->acount = 0;

+	pp->atime = nowms;

+	if(++pp->acount > Attachcount){

+		fprint(2, "%s: %s: port %d: too many attaches in short succession\n",

+			argv0, d->dir, p);

+		goto Fail;

+	}

+

 	pp->state = Pattached;

 	dprint(2, "%s: %s: port %d attach sts %#ux\n", argv0, d->dir, p, sts);

 	if(h->dev->isusb3){

@@ -558,7 +573,12 @@

 				dprint(2, "%s: %s: port %d: unsuspend: %r\n", argv0, d->dir, p);

 			sleep(Enabledelay);

 			sts = portstatus(h, p);

-			fprint(2, "%s: %s: port %d: unsuspended (sts %#ux)\n", argv0, d->dir, p, sts);

+			if(sts == -1){

+				hubfail(h);

+				return -1;

+			}

+			fprint(2, "%s: %s: port %d: unsuspended sts: %s %#ux\n", argv0, d->dir, p,

+				stsstr(sts, h->dev->isusb3), sts);

 		}

 	}

 	if((pp->sts & PSpresent) == 0 && (sts & PSpresent) != 0){

@@ -568,7 +588,7 @@

 	}else if(portgone(pp, sts)){

 		portdetach(h, p);

 	}else if(portresetwanted(h, p)){

-		portdetach(h, p);	

+		portdetach(h, p);

 		if(!d->isusb3)

 			portfeature(h, p, Fportenable, 0);

 		/* pretend it is gone, causing a re-attach and port reset */

@@ -614,7 +634,7 @@

 	 * Do not use hub interrupt endpoint because we

 	 * have to poll the root hub(s) in any case.

 	 */

-	for(;;){

+	for(;;nowms += pollms){

 		qlock(&hublock);

 Again:

 		for(h = hubs; h != nil; h = h->next)