addresses va's of 0 and -BY2PG cause trouble with some memmove()/memset()
implementations and possibly other code because of the nil pointer
and end pointers wrapping to zero.
unlock()/iunlock():
we need to place the coherence() *before* "l->key = 0", so that any
stores that where done while holding the lock become observable
*before* other processors see the lock released.
cas()/tas():
place memory barrier before successfull return to prevent reordering.
making sure to close the dot in every kproc appears repetitive,
so instead stop inheriting the dot in kproc() as this is usually
never what you wanted in the first place.
changing procmode has the nasty side effect that notes cannot
be posted to them, prventing sysfatal() and threadexitsall()
to cleanup properly.
recent kernels also check the noswap flag to void killing them
in out of memory condition, so this is really all we need now.
give kernel processes and local disk file servers (procs
having noswap flag set) a clear advantage for page allocation
under starved condition by giving them ther own wait queue so
they get readied as soon as pages become available.
check parent directory permission *after* we determined
that the new name does not exist in the parent, so that
when the new name is the same as old name then no write
permission is required in the parent directory.
instead of copying the whole packet, just save the
udp header and restore it aftwards. dont call redistrib()
when there are no forwards (this should be almost always
the case).
the code used P_Random()-P_Random() in some places which has
undefined evaluation order resulting in the wrong pseudo random
numbers being returned causing demo playback to desync.
this change adds P_Random2() function which returns the right
delta-random number and uses it in place of P_Random()-P_Random()
expression.
yoann padioleaus report on 9fans:
> I think I’ve found a bug in the network stack.
> in 9/ip/ip.h there is
> struct Ipht
> {
> Lock;
> Iphash *tab[Nipht];
> };
>
> where Night is 521,
>
> but then in 9/ip/ipaux.c there is
>
> ulong
> iphash(uchar *sa, ushort sp, uchar *da, ushort dp)
> {
> return ((sa[IPaddrlen-1]<<24) ^ (sp << 16) ^ (da[IPaddrlen-1]<<8) ^ dp ) % Nhash;
> }
>
> where Nhash is just 64,
