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Fix the BMC state decision algorithm. 

We failed to make the distinction between plain old "better" and
"better by topology," but the BMC algorithm really counts on this.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
master
Richard Cochran 2012-01-06 21:08:02 +01:00
parent 807ec32c96
commit c2fad7bd51
1 changed files with 27 additions and 11 deletions
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34
bmc.c
View File

@ -21,8 +21,10 @@
#include "bmc.h"
#include "ds.h"
#define A_BETTER_TOPO 2
#define A_BETTER 1
#define B_BETTER -1
#define B_BETTER_TOPO -2
static int dscmp2(struct dataset *a, struct dataset *b)
{
@ -37,21 +39,35 @@ static int dscmp2(struct dataset *a, struct dataset *b)
* We ignore the "error-1" conditions mentioned in the
* standard, since there is nothing we can do about it anyway.
*/
if (A < B)
return A_BETTER;
if (A > B)
return B_BETTER;
diff = memcmp(&a->sender, &b->sender, sizeof(a->sender));
if (A < B) {
diff = memcmp(&b->receiver, &b->sender, sizeof(b->receiver));
if (diff < 0)
return A_BETTER;
if (diff > 0)
return A_BETTER_TOPO;
/* error-1 */
return 0;
}
if (A > B) {
diff = memcmp(&a->receiver, &a->sender, sizeof(a->receiver));
if (diff < 0)
return B_BETTER;
if (diff > 0)
return B_BETTER_TOPO;
/* error-1 */
return 0;
}
diff = memcmp(&a->sender, &b->sender, sizeof(a->sender));
if (diff < 0)
return A_BETTER_TOPO;
if (diff > 0)
return B_BETTER_TOPO;
if (a->receiver.portNumber < b->receiver.portNumber)
return A_BETTER;
return A_BETTER_TOPO;
if (a->receiver.portNumber > b->receiver.portNumber)
return B_BETTER;
return B_BETTER_TOPO;
/*
* If we got this far, it means "error-2" has occured.
*/
@ -136,7 +152,7 @@ enum port_state bmc_state_decision(struct clock *c, struct port *r)
return PS_SLAVE; /*S1*/
}
if (dscmp(clock_best, port_best) > 0) {
if (dscmp(clock_best, port_best) == A_BETTER_TOPO) {
return PS_PASSIVE; /*P2*/
} else {
return PS_MASTER; /*M3*/