circumstances, caused perfectly good connections to be dropped. This
happened for connections over a LAN, where the retransmit timer
calculation TCP_REXMTVAL(tp) returned 0. If sending was blocked by flow
control for long enough, the old code dropped the connection, even
though timely replies were being received for all window probes.
Reviewed by: W. Richard Stevens <rstevens@noao.edu>
code without the B_READ flag being set. This is a problem when the
data is not cached, and the result will be a bogus attempted write.
Submitted by: Kato Takenori <kato@eclogite.eps.nagoya-u.ac.jp>
process during pmap_copy. This minimizes unnecessary swapping or creation of
swap space. If there is a hold_count flaw for page-table
pages, clear the page before freeing it to lessen the chance of a system
crash -- this is a robustness thing only, NOT a fix.
having a hosts.lpd(5) manpage and some references to it from
within lpd(8) might help here. Close PR docs/1277
Submitted by: andreas@knobel.gun.de (Andreas Klemm)
operations don't work with FICTITIOUS pages.) Also, close a window
between PG_MANAGED and pmap_enter that can mess up the accounting of
the managed flag. This problem could likely cause a hold_count error
for page table pages.
close some windows that are opened up by page table allocations. The
prefaulting code no longer uses hold counts, but now uses the busy
flag for synchronization.
Now that we preserve RPC handles instead of rebuilding them each time
a ypcln function is called, we have to be careful about keeping our sockets
in a sane state. It's possible that the caller may call a ypclnt
function, and then decide to close all its file descriptors. This would
also close the socket descriptor held by the yplib code. Worse, it
could re-open the same descriptor number for its own use. If it then calls
another ypclnt function, the subsequent RPC will fail because the socket
will either be gone or replaced with Something Completely Different. The
yplib code will recover by rebinding, but it doing so it may wreck the
descriptor which now belongs to the caller.
To fix this, _yp_dobind() needs to label the descriptor somehow so
that it can test it later to make sure it hasn't been altered between
ypclnt calls. It does this by binding the socket, thus associating a port
number with it. It then saves this port number in the dom_local_port member
of the dom_binding structure for the given domain. When _yp_dobind() is
called again (which it is at the start of each ypclnt function), it checks
to see if the domain is already bound, and if it is, it does a getsockname()
on the socket and compares the port number to the one it saved. If the
getsockname() fails, or the port number doesn't match, it abandons the
socket and sets up a new client handle.
This still incurs some syscall overhead, which is what I was trying to
avoid, but it's still not as bad as before.
functions are implimented as wrappers around getservent(), which means it's
up to getservent() to do all the work. The NIS support in getservent()
only allows it to scan through the services.byname map one entry at a
time until it finds the requested service name/port. This can be painfully
slow due to the overhead involved (lots and lots of successive RPCs).
To fix this, we allow getservbyname() and getservbyport() to signal
getservent() that if NIS is turned on (there's a '+' in /etc/services),
the usual yp_first()/yp_next() linear search should be abandoned and
yp_match() used instead. This causes getservent() to immediately
locate the requested entry instead of wasting time groping through the
whole map.
The downside is that this trick is accomplished by exporting a couple of
pointers from getservent.c which getservbyname.c and getservbyport.c can
preset in order to tell getservent() what to do. If all three functions
were in the same source module, then the extra cruft could be delcared
static to avoid poluting the global symbol space. Maybe they should be
combined anyway. For now I've settled on prepending lots of underscores.
