[retry] Rewrite unrelicensable portions of retry.c

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/retry.h

  *
  */
 
-FILE_LICENCE ( GPL2_OR_LATER );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <ipxe/list.h>
 
-/** Default timeout value */
+/** Default minimum timeout value (in ticks) */
 #define DEFAULT_MIN_TIMEOUT ( TICKS_PER_SEC / 4 )
 
-/** Limit after which the timeout will be deemed permanent */
+/** Default maximum timeout value (in ticks) */
 #define DEFAULT_MAX_TIMEOUT ( 10 * TICKS_PER_SEC )
 
 /** A retry timer */
 	unsigned int running;
 	/** Timeout value (in ticks) */
 	unsigned long timeout;
-	/** Minimum timeout value (in ticks)
+	/** Minimum timeout value (in ticks), or zero to use default
 	 *
-	 * A value of zero means "use default timeout."
+	 * The timeout will never be reduced below this value.
 	 */
-	unsigned long min_timeout;
-	/** Maximum timeout value before failure (in ticks)
+	unsigned long min;
+	/** Maximum timeout value (in ticks), or zero to use default
 	 *
-	 * A value of zero means "use default timeout."
+	 * The timeout will be deemed permanent (according to the
+	 * failure indicator passed to expired()) when it exceeds this
+	 * value.
 	 */
-	unsigned long max_timeout;
+	unsigned long max;
 	/** Start time (in ticks) */
 	unsigned long start;
 	/** Retry count */
 	 *
 	 * The timer will already be stopped when this method is
 	 * called.  The failure indicator will be True if the retry
-	 * timeout has already exceeded @c MAX_TIMEOUT.
+	 * timeout has already exceeded @c max_timeout.
 	 */
 	void ( * expired ) ( struct retry_timer *timer, int over );
 	/** Reference counter
 	return ( timer->running );
 }
 
+/**
+ * Set minimum and maximum timeouts
+ *
+ * @v timer		Retry timer
+ * @v min		Minimum timeout (in ticks), or zero to use default
+ * @v max		Maximum timeout (in ticks), or zero to use default
+ */
+static inline __attribute__ (( always_inline )) void
+set_timer_limits ( struct retry_timer *timer, unsigned long min,
+		   unsigned long max ) {
+	timer->min = min;
+	timer->max = max;
+}
+
 #endif /* _IPXE_RETRY_H */

src/net/neighbour.c

 	memcpy ( neighbour->net_dest, net_dest,
 		 net_protocol->net_addr_len );
 	timer_init ( &neighbour->timer, neighbour_expired, &neighbour->refcnt );
-	neighbour->timer.min_timeout = NEIGHBOUR_MIN_TIMEOUT;
-	neighbour->timer.max_timeout = NEIGHBOUR_MAX_TIMEOUT;
+	set_timer_limits ( &neighbour->timer, NEIGHBOUR_MIN_TIMEOUT,
+			   NEIGHBOUR_MAX_TIMEOUT );
 	INIT_LIST_HEAD ( &neighbour->tx_queue );
 
 	/* Transfer ownership to cache */

src/net/retry.c

  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
  */
 
-FILE_LICENCE ( GPL2_OR_LATER );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stddef.h>
 #include <ipxe/timer.h>
  *
  * This implementation of the timer is designed to satisfy RFC 2988
  * and therefore be usable as a TCP retransmission timer.
- *
  * 
  */
 
 static LIST_HEAD ( timers );
 
 /**
- * Start timer
+ * Start timer with a specified timeout
  *
  * @v timer		Retry timer
+ * @v timeout		Timeout, in ticks
  *
- * This starts the timer running with the current timeout value.  If
+ * This starts the timer running with the specified timeout value.  If
  * stop_timer() is not called before the timer expires, the timer will
  * be stopped and the timer's callback function will be called.
  */
-void start_timer ( struct retry_timer *timer ) {
+void start_timer_fixed ( struct retry_timer *timer, unsigned long timeout ) {
+
+	/* Add to list of running timers (if applicable) */
 	if ( ! timer->running ) {
 		list_add ( &timer->list, &timers );
 		ref_get ( timer->refcnt );
+		timer->running = 1;
 	}
+
+	/* Record start time */
 	timer->start = currticks();
-	timer->running = 1;
-
-	/* 0 means "use default timeout" */
-	if ( timer->min_timeout == 0 )
-		timer->min_timeout = DEFAULT_MIN_TIMEOUT;
-	/* We must never be less than MIN_TIMEOUT under any circumstances */
-	if ( timer->min_timeout < MIN_TIMEOUT )
-		timer->min_timeout = MIN_TIMEOUT;
-	/* Honor user-specified minimum timeout */
-	if ( timer->timeout < timer->min_timeout )
-		timer->timeout = timer->min_timeout;
+
+	/* Record timeout */
+	timer->timeout = timeout;
 
 	DBG2 ( "Timer %p started at time %ld (expires at %ld)\n",
 	       timer, timer->start, ( timer->start + timer->timeout ) );
 }
 
 /**
- * Start timer with a specified fixed timeout
+ * Start timer
  *
  * @v timer		Retry timer
- * @v timeout		Timeout, in ticks
+ *
+ * This starts the timer running with the current timeout value
+ * (rounded up to the minimum timeout value).  If stop_timer() is not
+ * called before the timer expires, the timer will be stopped and the
+ * timer's callback function will be called.
  */
-void start_timer_fixed ( struct retry_timer *timer, unsigned long timeout ) {
-	start_timer ( timer );
-	timer->timeout = timeout;
-	DBG2 ( "Timer %p expiry time changed to %ld\n",
-	       timer, ( timer->start + timer->timeout ) );
+void start_timer ( struct retry_timer *timer ) {
+	unsigned long timeout = timer->timeout;
+	unsigned long min;
+
+	/* Calculate minimum timeout */
+	min = ( timer->min ? timer->min : DEFAULT_MIN_TIMEOUT );
+	if ( min < MIN_TIMEOUT )
+		min = MIN_TIMEOUT;
+
+	/* Ensure timeout is at least the minimum */
+	if ( timeout < min )
+		timeout = min;
+
+	/* Start timer with this timeout */
+	start_timer_fixed ( timer, timeout );
 }
 
 /**
  */
 static void timer_expired ( struct retry_timer *timer ) {
 	struct refcnt *refcnt = timer->refcnt;
+	unsigned long max = ( timer->max ? timer->max : DEFAULT_MAX_TIMEOUT );
 	int fail;
 
 	/* Stop timer without performing RTT calculations */
 
 	/* Back off the timeout value */
 	timer->timeout <<= 1;
-	if ( timer->max_timeout == 0 ) /* 0 means "use default timeout" */
-		timer->max_timeout = DEFAULT_MAX_TIMEOUT;
-	if ( ( fail = ( timer->timeout > timer->max_timeout ) ) )
-		timer->timeout = timer->max_timeout;
+	if ( ( fail = ( timer->timeout > max ) ) )
+		timer->timeout = max;
 	DBG ( "Timer %p timeout backed off to %ld\n",
 	      timer, timer->timeout );
 

src/net/udp/dhcp.c

 	dhcp->state = state;
 	dhcp->start = currticks();
 	stop_timer ( &dhcp->timer );
-	dhcp->timer.min_timeout = state->min_timeout_sec * TICKS_PER_SEC;
-	dhcp->timer.max_timeout = state->max_timeout_sec * TICKS_PER_SEC;
+	set_timer_limits ( &dhcp->timer,
+			   ( state->min_timeout_sec * TICKS_PER_SEC ),
+			   ( state->max_timeout_sec * TICKS_PER_SEC ) );
 	start_timer_nodelay ( &dhcp->timer );
 }