change Proc.nlocks from Ref to int and just use normal increment and decrelemt
as done in erik quanstros 9atom.
It is not clear why we used atomic increment in the fist place as even if we
get preempted by interrupt and scheduled before we write back the incremented
value, it shouldnt be a problem and we'll just continue where we left off as
our process is the only one that can write to it.
Yoann Padioleau found that the Mach pointer Lock.m wasnt maintained
consistently for lock() vs canlock() and ilock(). Fixed.
Use uintptr instead of ulong for maxlockpc, maxilockpc and ilockpc debug variables.
webfs forks the namespace to isolate itself from its mount
point which has the side effect that it captures the mount
of previous instances of webfs mounted on /mnt/web.
explicitely unmount the mountpoint in our namespace copy
to drop the reference.
when there are multiple readers of /dev/usbevent, we have to
serialize the processing to make sure that only one driver
is opening the devices control endpoint at a time.
to do this, we assume the device is busy after reading the
event file until the next read or clunk on the same fid.
to mark a device busy, we set the dev->aux pointer to the
fid processing a event. And the Event structure takes a
reference to the device producing the event.
the problem arised from cdc ethernet and nusb/serial sharing
the same device class, and we need to run the particular driver
to figure out if the device can be used. doing this concurrently
fails because devusb allows only one open per endpoint.
the palloc.pages array takes arround 5% of the upages which
gives us:
16GB = ~0.8GB
32GB = ~1.6GB
64GB = ~3.2GB
we only have 2GB of address space above KZERO so this will not
work for long.
instead, pageinit() was altered to accept a preallocated memory
in palloc.pages. and preallocpages() in pc64/main.c allocates the
in upages memory, mapping it in the VMAP area (which has 512GB).
the drawback is that we cannot poke at Page structures now from
/proc/n/mem as the VMAP area is not accessible from it.
Without an explicit signal for a truncation, copy propagation will
sometimes propagate a 32-bit truncation and end up overwriting uses of
the original 64-bit value.
This was independently discovered and fixed in Go. See:
http://golang.org/issue/1315https://codereview.appspot.com/6002043/
Thanks Charles Forsyth for tips and advice.
as we do system reset and reboot only from boot processor cpu0 now,
theres no need for active.rebooting conditional variable.
mpshutdown() will unconditionally park application processors and
and cpu0 boots the new kernel or calls mpshutdown() causing system
reset.
in vmware, mpshutdown() used to hang in i8042reset() when not
called from the boot processor, so instead of reseting from first
cpu that acquires the shutdown lock, we park all application
processors and let the boot processor do the reset.
procwrite() did truncate the offset to 32bit ulong.
introduce off2addr() function that does the sign
extension hack and use it conststently for Qmem
reads and writes.
for the CMclose procctl, the fd number was not
bounds checked before indexing in the Fgrp.fd
array.
for the CMclosefiles, we looped fd from 0..maxfd-1,
but need to loop from 0..maxfd as maxfd is inclusive.
newns() (called by auth_chuid()) already prepares the
environment variables and puts us in a sane working
directory (as specified by the namespace file).
on amd64, the text segment is aligned and padded to
2MB, but segment granularity is 4K which can give
us page faults that are beyond the highest file
offset. this is perfectly valid, but was not handled
correctly in pio().
use two per process memory slots, one for the
pid and one for the fd instead of a global table
avoiding the case when the table gets full.
instead of calling pread() on the cached fd
(dangerous as it has side effects when the
fd was not closed), we check if the cached fd
is still good using fd2path() when called
the first time in this process.
theres big performance regression with this using
cwfs. cwfs calls time() to update atime on every
read/write which now causes walks on /dev.
reverting to the previous version for now. in the
long run, we'll use new _nsec() syscall but this
has to wait for a later release once new kernels
are established.
