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SubjectRe: [PATCH] net/ipv4/*, net/core/neighbour.c jiffies cleanup
> Why do they these cases that are actually in the code need to cast to
> a signed value to get a correct answer? They are not like your
> example.
>
> Almost all of these cases are:
>
> (jiffies - SOME_VALUE_KNOWN_TO_BE_IN_THE_PAST) > 5 * HZ
>
> So you say if we don't cast to signed, this won't get it right on
> wrap-around? I disagree, let's say "long" is 32-bits and jiffies
> wrapped around to "0x2" and SOME_VALUE... is 0xfffffff8. The
> subtraction above yields 10, and that is what we want.
>
> Please show me a bad case where casting to signed is necessary.
>
> I actually ran through the tree the other night myself starting to
> convert these things, then I noticed that I couldn't even convince
> myself that the code was incorrect.
>


Please consider to change the appended ones.

Tim


--- linux-2.4.14/net/ipv4/route.c Wed Oct 31 00:08:12 2001
+++ linux-2.4.14-jiffies64/net/ipv4/route.c Wed Nov 7 22:51:23 2001
@@ -395,7 +395,7 @@
write_unlock(&rt_hash_table[i].lock);

/* Fallback loop breaker. */
- if ((jiffies - now) > 0)
+ if ((long)(jiffies - now) > 0)
break;
}
rover = i;
--- linux-2.4.14/net/ipv4/ipconfig.c Wed Oct 31 00:08:12 2001
+++ linux-2.4.14-jiffies64/net/ipv4/ipconfig.c Wed Nov 7 23:28:47 2001
@@ -1000,7 +1000,7 @@
#endif

jiff = jiffies + (d->next ? CONF_INTER_TIMEOUT : timeout);
- while (jiffies < jiff && !ic_got_reply)
+ while ((long)(jiffies - jiff) < 0 && !ic_got_reply)
barrier();
#ifdef IPCONFIG_DHCP
/* DHCP isn't done until we get a DHCPACK. */
@@ -1113,7 +1113,7 @@
try_try_again:
/* Give hardware a chance to settle */
jiff = jiffies + CONF_PRE_OPEN;
- while (jiffies < jiff)
+ while ((long)(jiffies - jiff) < 0)
;

/* Setup all network devices */
@@ -1122,7 +1122,7 @@

/* Give drivers a chance to settle */
jiff = jiffies + CONF_POST_OPEN;
- while (jiffies < jiff)
+ while ((long)(jiffies - jiff) < 0)
;

/*
-
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