Before, we would just leak all the "Conn"
structures.
fshangup() could cause problems as it just
forcefully closes the file descriptors,
not considering someone else going to
write them afterwards.
Instead, we add a "hangup" flag to Conn,
which readers and writers check before
attempting i/o.
And we only close the file-descriptors
when the last reader/writer drops the
connection. (Make it ref-counted).
For faster teardown, also preserve the
"ctl" file descriptor from listen()
amd use it to kill the connection quickly
when fshangup() is called.
When at the task of decomposing a rune into its
"button" and "rune", also consider the keyboard
map table with the escaped scancodes.
This fixes Shift + left/right combinations in
drawterm.
For each connection, remember if authentication
protocol ran successfully and only then, allow
attach as 'none' user.
This prevents anonymous remote mounts of none.
The 'none' user also shouldnt attach to the dump
file system.
The Tauth for "none" should always fail,
but Tattach should only succeed when
the channel ran a successfull authentication
before.
Also, prevent "none" from attaching "dump".
We want to implement "none" attaches for hjfs,
but only if the 9p-"channel" ran a successfull
authentication before, to prevent anonymous
remote mounts as "none".
Add a flag to the Srv struct for this.
Before this it was possible to Tauth and Tattach with one
user name and then authenticate with factotum using a different
user name. To fix this we now ensure that the uname matches the returned
cuid from AuthInfo.
This security bug is still pending a cute mascot and theme song.
when appending to a directory, the copy of the offset in the dent was
set to the offset that the write was supposed to happen at -- however,
for DMAPPEND files the offset is always at the end of the file. Until
the file was closed, stat would show the wrong directory info.
Implement a hangup ctl command that flushes the
queues, but keeps the filter around.
This can be usefull for low-overhead traffic blocking,
as only the file-descriptor needs to be kept around
and the queues can be flushed.
No user-space process is needed to consume packets
and no buffers are wasted.
example:
aux/dial -e -o hangup 'ipmux!ver=4;src=8.8.8.8' rc -c 'echo 0 > /srv/blocked'
rm /srv/blocked
It seems some protocols are unprepared to
deal with ipoput*() raising an error
(thrown from ifc->m->bwrite()).
so catch it and return -1 (no route) instead.
We were accidentally searching the key for '&', instead of the value.
Inferno received this exact fix at some point, but it never made it back to Plan 9.
the installed version of git has a bug; removing
this file will trigger some spurious removals of
test files, so hold off deleting it until people
have time to install a fixed git
directories need to sort as though they end with a '/',
when running through them for comparison, otherwise we
flag files as added and removed spuriously, leading to
them incorrectly getting deleted when merging commits.
Instead of Proc { Mach *mp; Mach *wired; },
track affinity by an integer representing
the mach number instead.
This simplifies the code as it avoids needing
to compare with MACHP(m->machno).
Wiering a process to a processor is now done
by just assigning affinity and then set a flag
that it should not change.
Call procpriority() when we want to change
priority of a process instead of managing
the fields directly.
The idea is:
When we call sched() with interrupts disabled,
it must not return with them re-enabled.
The code becomes easier to reason about if
we make sched() preserve interrupt status,
which lets us call sched() from an interrupt
handler (with interrupts disabled) without
risking preemption by another interrupt once
sched() returns which can pump-up the stack.
This allows removing Proc.preempted flag as
it is now impossible for interrupts to
preempt each other in preempted().
Extra cleanups:
make interrupted() _Noreturn void
and remove unused Proc.yield flag.
the symptom is that ping is apparently skipping
transmits which recover with the next send,
resulting in exactly send-period spikes in
the ping rtt.
It appears that the core seems to reorder writes
to uncached memory, which can result in the doorbell
being written before the descriptor status bits
are written.
put a coherence() barrier before writing doorbell
fixes it.
thanks sigrid for reporting the issue!
On a multiprocessor, the scheduler can run into
a very unfair distribution of processes to cpus
when there are more long-running processes than cpus.
Say we have a 4 cpu machine and we run 4 long-running
proesses, each cpu will pick up a single process
and each process will get 100% of its fair share.
Everything is good so far.
If we start more long-running processes, all these
processes are going to be picked up by the cpu core
that runs most sporanic / bursty work loads as it
is calling sched() more often.
This results in all the extra long-running prcoesses
to cluster around the same core resulting in very
unfair sharing of load.
The problem is that once a process runs on a cpu,
it stays on that cpu as processor affinity
is never reset.
Process migration only happens when a cpu cannot
find any process to run, given the affinity
constrains, but this can never happen when
the system is under full load and each cpu
always has a low-priority long running
process to run.
How do we fix this?
The idea of this hack is to reset processor
affinity in ready() when its priority changes or,
when it appears to be a long-running process.
That way, we give every cpu a chance to pick
it up and share the load.
This is not a ideal solution of course. Long term,
we should probably have separate runqueues per cpu
and do the balancing explicitely.
