code: plan9front

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usbxhci: add some robustness checks

Add some checks in the interrupt handler to ensure
that the slot and ring referred to by the event have
been initialized.

Also add a check in ctlrcmd() just in case we mess
up the recovery and someone issues a ctlrcmd() after
a failed xhciinit().

--- a/sys/src/9/port/usbxhci.c

+++ b/sys/src/9/port/usbxhci.c

@@ -815,6 +815,10 @@

 		qunlock(&ctlr->cmdlock);

 		return Erecover;

 	}

+	if(ctlr->cr->base == nil || ctlr->cr->ctlr != ctlr){

+		qunlock(&ctlr->cmdlock);

+		return Egreg;

+	}

 	ctlr->cr->stopped = 0;

 	queuetd(ctlr->cr, c, s, p, w);

 	err = waittd(w, 5000);

@@ -833,6 +837,9 @@

 	u32int *td, x;

 	u64int pa;

+	if(r->base == nil || r->ctlr != ctlr)

+		return;

+

 	pa = (*(u64int*)er) & ~15ULL;

 	ilock(r);

 	for(x = r->rp; (int)(r->wp - x) > 0; x++){

@@ -876,7 +883,7 @@

 	Slot *slot;

 	u32int *irs, *td, x;

-	if(ring->base == nil)

+	if(ring->base == nil || ring->ctlr != ctlr)

 		return;

 	irs = &ctlr->rts[IR0];

@@ -899,7 +906,7 @@

 			if(x == 0 || x > ctlr->nslots)

 				break;

 			slot = ctlr->slot[x];

-			if(slot == nil)

+			if(slot == nil || slot->ctlr != ctlr)

 				break;

 			completering(ctlr, &slot->epr[(td[3]>>16)-1&31], td);

 			break;

@@ -935,7 +942,7 @@

 	if(arg == nil)

 		return;

 	slot = arg;

-	if(slot->id != 0){

+	if(slot->id > 0){

 		Ctlr *ctlr = slot->ctlr;

 		qlock(&ctlr->slotlock);

 		if(ctlr->slot != nil

@@ -1464,7 +1471,6 @@

 static char*

 unstall(Ep *ep, Ring *r)

 {

-	Ctlr *ctlr = r->slot->ctlr;

 	char *err;

 	switch(r->ctx[0]&7){

@@ -1474,16 +1480,15 @@

 	}

 	if(ep->clrhalt){

 		ep->clrhalt = 0;

-		err = ctlrcmd(ctlr, CR_RESETEP | (r->id<<16) | (r->slot->id<<24), 0, 0, nil);

-		dmaflush(0, r->ctx, 8*4 << ctlr->csz);

+		err = ctlrcmd(r->ctlr, CR_RESETEP | (r->id<<16) | (r->slot->id<<24), 0, 0, nil);

+		dmaflush(0, r->ctx, 8*4 << r->ctlr->csz);

 		if(err != nil)

 			return err;

 		r->stopped = 1;

 	}

 	if(r->stopped){

-		err = ctlrcmd(ctlr, CR_SETTRDQP | (r->id<<16) | (r->slot->id<<24), 0,

-			resetring(r), nil);

-		dmaflush(0, r->ctx, 8*4 << ctlr->csz);

+		err = ctlrcmd(r->ctlr, CR_SETTRDQP | (r->id<<16) | (r->slot->id<<24), 0, resetring(r), nil);

+		dmaflush(0, r->ctx, 8*4 << r->ctlr->csz);

 		if(err != nil)

 			return err;

 		r->stopped = 0;