shithub: riscv

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ref: acb206859deafd32c5ef1901560dc13be2c0d280
parent: 069230cd621ae5b3b9ab6e1a31eb6250fc86e30b
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Sun Jan 7 19:23:26 EST 2018

ether8169: deal with kernel memory exhaution

when kernel memory is exhausted, rtl8169replenish() can fail
to plant more receive descriptors and rtl8169receive() would
run over the receive tail and crash on the nil ctlr->rb[x].

rtl8169receive() is called on "Receive Descriptor Unavailable"
and "Packet Underrun" so we will try to replenish descriptors
in the beginning first in case memory was exhausted and memory
is available again and make sure not to run over the tail.

--- a/sys/src/9/pc/ether8169.c

+++ b/sys/src/9/pc/ether8169.c

@@ -919,8 +919,10 @@

 	int x;

 	ctlr = edev->ctlr;

-	x = ctlr->rdh;

-	for(;;){

+	if(ctlr->nrq < ctlr->nrd/2)

+		rtl8169replenish(ctlr);

+

+	for(x = ctlr->rdh; x != ctlr->rdt;){

 		d = &ctlr->rd[x];

 		if((control = d->control) & Own)

 			break;