The reason for this change is that currently, a send/recv
takes many hours to time out.
This is suboptimal in the bootloader because it means for example
that NFS will take hours to fail before allowing subsequent access
methods such as gzip to be tried.
Setting MAXWAIT to 300 seconds (5 minutes) still allows slow
connections of 1Mb to be used to download a 30MB kernel file.
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D18544
Current timeout behavior is to progress in timeout values from MINTMO to
MAXTMO in MINTMO steps before finally timing out. This results in a fairly
long time before operations finally timeout, which may not be ideal for some
use-cases.
Add MAXWAIT that may be configured along with MINTMO/MAXTMO. If we attempt
to start our send/recv cycle over again but MAXWAIT > 0 and MAXWAIT seconds
have already passed, then go ahead and timeout.
This is intended for those that just want to say "timeout after 180 seconds"
rather than calculate and tweak MINTMO/MAXTMO to get their desired timeout.
The default is 0, or "progress from MINTMO to MAXTMO with no exception."
This has been modified since review to allow for it to be defined via CFLAGS
and doing appropriate error checking. Future work may add some Makefile foo
to respect LOADER_NET_MAXWAIT if it's specified in the environment and pass
it in as MAXWAIT accordingly.
Reviewed by: imp, sbruno, tsoome (all previous version)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D14389
bootp/arp/rarp/rpc all use the sendrecv implementation in net.c. tftp has
its own implementation because it passes an extra parameter into the recv
callback for the received payload type to be held.
These sendrecv implementations are otherwise equivalent, so consolidate
them. The other users of sendrecv won't be using the extra argument to recv,
but this gives us only one place to worry about respecting timeouts and one
consistent timeout behavior.
Tested by: sbruno
Reviewed by: sbruno, tsoome
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D14373
readip() doesn't, at the moment, properly indicate to callers that it has
timed out. One can tell that it's timed out if errno == EAGAIN when it
returns, but this is not ideal. Restructure it a little bit to explicitly
set errno to ETIMEDOUT if we've exhausted tleft.
I found two places that care about where it timed out or not: sendrecv in
net.c and sendrecv_tftp. Both are structured to pass smaller timeout values
to readip while tracking a larger timeout. Neither of them were able to do
this properly with readip not indicating ETIMEDOUT, so fix it.
While here, straighten out the time (t/t1) usage in sendrecv_tftp.
This would have manifested itself in periodic failures to NFS/TFTP boot for
no apparent reason because MINTMO/MAXTMO were not actually being respected
properly. Problems were not reported with NFS, only TFTP.
Reported by: sbruno
Reviewed by: sbruno, tsoome
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D14350
