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[dhcp] Limit maximum number of DHCP discovery deferrals 

For switches which remain permanently in the non-forwarding state (or
which erroneously report a non-forwarding state), ensure that iPXE
will eventually give up waiting for the link to become unblocked.

Originally-fixed-by: Wissam Shoukair <wissams@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2015-11-10 14:05:46 +00:00
parent d5f7ee60e7
commit ed0d7c4f6f
2 changed files with 12 additions and 2 deletions
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6
src/config/dhcp.h
View File

@ -24,6 +24,12 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
//#define DHCP_DISC_START_TIMEOUT_SEC 4 /* as per PXE spec */
//#define DHCP_DISC_END_TIMEOUT_SEC 32 /* as per PXE spec */
/*
* Maximum number of discovery deferrals due to blocked links
* (e.g. from non-forwarding STP ports)
*/
#define DHCP_DISC_MAX_DEFERRALS 60
/*
* ProxyDHCP offers are given precedence by continue to wait for them
* after a valid DHCPOFFER is received. We'll wait through this

8
src/net/udp/dhcp.c
View File

@ -444,7 +444,8 @@ static void dhcp_discovery_expired ( struct dhcp_session *dhcp ) {
unsigned long elapsed = ( currticks() - dhcp->start );
/* If link is blocked, defer DHCP discovery (and reset timeout) */
if ( netdev_link_blocked ( dhcp->netdev ) ) {
if ( netdev_link_blocked ( dhcp->netdev ) &&
( dhcp->count <= DHCP_DISC_MAX_DEFERRALS ) ) {
DBGC ( dhcp, "DHCP %p deferring discovery\n", dhcp );
dhcp->start = currticks();
start_timer_fixed ( &dhcp->timer,
@ -1115,7 +1116,7 @@ static int dhcp_tx ( struct dhcp_session *dhcp ) {
* session state into packet traces. Useful for extracting
* debug information from non-debug builds.
*/
dhcppkt.dhcphdr->secs = htons ( ( ++(dhcp->count) << 2 ) |
dhcppkt.dhcphdr->secs = htons ( ( dhcp->count << 2 ) |
( dhcp->offer.s_addr ? 0x02 : 0 ) |
( dhcp->proxy_offer ? 0x01 : 0 ) );
@ -1259,6 +1260,9 @@ static void dhcp_timer_expired ( struct retry_timer *timer, int fail ) {
return;
}
/* Increment transmission counter */
dhcp->count++;
/* Handle timer expiry based on current state */
dhcp->state->expired ( dhcp );
}