string as possible and return ENOMEM if the entire string cannot
be returned. This brings the routines in line with how the man
page says they work, and how the calling routines are expecting
them to work. This allows the dummy uname() routine in libc to
obtain the version string, since the kernel version string is
longer than that normally returned by the uname() routine.
This is 3/4 of the fix for PR# 462.
Reviewed by: Bruce Evans
as is required to be POSIXLY_CORRECT and "right". I interpret
"referring to a directory" as being a directory or becoming a
directory. E.g., the trailing slashes in mkdir("/nonesuch/"),
rename("/tmp", /nonesuch/") and link("/tmp", "/root_can_like_dirs/")
are ignored because the target will become a directory if the
syscall succeeds. A trailing slash on a symlink causes the symlink
to be followed (this is a bug if the symlink doesn't point to a
directory; fix later).
queues for TIOCSETA[W]. Swapping an even number of times broke
the queue resource limits. This would have broken CRTSCTS flow
control if the clist slush list was used up.
Don'concatenate the queues for TIOCSETA[W] if one of the queues
has a resource limit of 0. Concatenation would cause a panic if
one of the queues is nonempty and the other is limited to length
0. This may have caused panics in PPPDISC.
Wake up readers after all transitions of ICANON. When ICANON is
turned off it is quite likely that characters will become available
to be read.
Reduce indentation near these changes.
on output below low water) and TS_SO_OCOMPLETE (sleep on output complete).
Most of the support for this has already been committed. Drivers should
call ttwwakeup() to handle wakeups whenever output is below low water
(and some output event causes this condition to be checked) or TS_BUSY is
cleared.
tty.c:
Fix the livelock in ttywait() properly by sleeping on output complete, not
on output below low water.
Use ttwwakeup() instead of separate select and output wakeups for all
wakeups of writers.
Add wakeups of writers for output flushes and carrier/clocal transitions.
Don't go to sleep in ttycheckoutq() if ttstart() reduces the queue to below
low water.
Use the timeout built into tsleep() in ttycheckoutq().
Optimize the select wakeup in ttwwakeup(). It seems reasonable to know
too much about the internals of tp->t_wsel now that the knowledge is
localised in tty.c.
Remove nullmodem().
It may be useful to have a null modem routine, but nullmodem()
wasn't one. nullmodem() was identical to ttymodem() except it
didn't implement MDMBUF (carrier) flow control, didn't do any
wakeups for off to on carrier transitions, and didn't flush the
i/o queues for on to off carrier transitions (flushing has the side
effect of waking up readers and writers) although it did generate
SIGHUPs. The wakeups must normally be done even if nullmodem() is
null in case something is sleeping waiting for a carrier transition.
In any case, the wakeups should be harmless. They may cause bogus
results for select(), but select() is already bogus for nonstandard
line disciplines.
different types of panics/inconsistencies with NFS clients.
Cleared PG_WANTED where appropriate.
Added checks for buffer busy in allocbuf and biodone.
Reviewed by: John Dyson
ended that fork() uses to determine the time that the process
started when calculating the elapsed time. This prevents the
ac_etime field in the accounting record from getting set to -1
if the process exists for a VERY short period of time.
ttwwakeup(). The conditions for doing the wakeup will soon become
more complicated and I don't want them duplicated in all drivers.
It's probably not worth making ttwwakeup() a macro or an inline
function. The cost of the function call is relatively small when
there is a process to wake up. There is usually a process to wake
up for large writes and the system call overhead dwarfs the function
call overhead for small writes.
Temporarily nuke TS_WOPEN. It was only used for the obscure MDMBUF
flow control option in the kernel and for informational purposes
in `pstat -t'. The latter worked properly only for ptys. In
general there may be multiple processes sleeping in open() and
multiple processes that successfully opened the tty by opening it
in O_NONBLOCK mode or during a window when CLOCAL was set. tty.c
doesn't have enough information to maintain the flag but always
cleared it in ttyopen().
TS_WOPEN should be restored someday just so that `pstat -t' can
display it (MDMBUF is already fixed). Fixing it requires counting
of processes sleeping in open() in too many serial drivers.
Don't put partial PARMRK escape sequences in the input queue. Use
MAX_INPUT = TTYHOG instead of TTYHOG directly for the maximum input
queue size. Don't use the bogus MAX_INPUT advertised in
<sys/syslimits.h>.
First of many changes required to restore lost stability to the tty
driver.
ECHONL is supposed to enable echoing of NL when ECHO is off, but it
enabled echoing of everything except NL.
VBLK vnodes isn't adequate since all NFS nodes aren't locked, either. The
result is a race condition that would lead to duplicate buffers at the
same block offset.
Submitted by: John Dyson
emul code when compiling with "options KTRACE".
ktrsyscall() was expecting an array of integers, this was passing the
address of a structure containing an array of integers..
The cosmetic problem was that it was calling the "enter syscall"
trace hook twice - this looks like a cut/paste error/typo.
notebooks where a powerfail condition (external power drop; battery
state low) is signalled by an NMI. Makes it beep instead of panicing.
Reviewed by: davidg
made a change to NFS that caused buffers at EOF to be variable size. This
had the undesired side-effect of breaking delayed writes on NFS. This
fixes it.
Submitted by: John Dyson
proc or any VM system structure will have to be rebuilt!!!
Much needed overhaul of the VM system. Included in this first round of
changes:
1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
haspage, and sync operations are supported. The haspage interface now
provides information about clusterability. All pager routines now take
struct vm_object's instead of "pagers".
2) Improved data structures. In the previous paradigm, there is constant
confusion caused by pagers being both a data structure ("allocate a
pager") and a collection of routines. The idea of a pager structure has
escentially been eliminated. Objects now have types, and this type is
used to index the appropriate pager. In most cases, items in the pager
structure were duplicated in the object data structure and thus were
unnecessary. In the few cases that remained, a un_pager structure union
was created in the object to contain these items.
3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
be removed. For instance, vm_object_enter(), vm_object_lookup(),
vm_object_remove(), and the associated object hash list were some of the
things that were removed.
4) simple_lock's removed. Discussion with several people reveals that the
SMP locking primitives used in the VM system aren't likely the mechanism
that we'll be adopting. Even if it were, the locking that was in the code
was very inadequate and would have to be mostly re-done anyway. The
locking in a uni-processor kernel was a no-op but went a long way toward
making the code difficult to read and debug.
5) Places that attempted to kludge-up the fact that we don't have kernel
thread support have been fixed to reflect the reality that we are really
dealing with processes, not threads. The VM system didn't have complete
thread support, so the comments and mis-named routines were just wrong.
We now use tsleep and wakeup directly in the lock routines, for instance.
6) Where appropriate, the pagers have been improved, especially in the
pager_alloc routines. Most of the pager_allocs have been rewritten and
are now faster and easier to maintain.
7) The pagedaemon pageout clustering algorithm has been rewritten and
now tries harder to output an even number of pages before and after
the requested page. This is sort of the reverse of the ideal pagein
algorithm and should provide better overall performance.
8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
have been removed. Some other unnecessary casts have also been removed.
9) Some almost useless debugging code removed.
10) Terminology of shadow objects vs. backing objects straightened out.
The fact that the vm_object data structure escentially had this
backwards really confused things. The use of "shadow" and "backing
object" throughout the code is now internally consistent and correct
in the Mach terminology.
11) Several minor bug fixes, including one in the vm daemon that caused
0 RSS objects to not get purged as intended.
12) A "default pager" has now been created which cleans up the transition
of objects to the "swap" type. The previous checks throughout the code
for swp->pg_data != NULL were really ugly. This change also provides
the rudiments for future backing of "anonymous" memory by something
other than the swap pager (via the vnode pager, for example), and it
allows the decision about which of these pagers to use to be made
dynamically (although will need some additional decision code to do
this, of course).
13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
object" code has been removed. MAP_COPY was undocumented and non-
standard. It was furthermore broken in several ways which caused its
behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
continue to work correctly, but via the slightly different semantics
of MAP_PRIVATE.
14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
threads design can be worked around in other ways. Both #12 and #13
were done to simplify the code and improve readability and maintain-
ability. (As were most all of these changes)
TODO:
1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
this will reduce the vnode pager to a mere fraction of its current size.
2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
information provided by the new haspage pager interface. This will
substantially reduce the overhead by eliminating a large number of
VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
improved to provide both a "behind" and "ahead" indication of
contiguousness.
3) Implement the extended features of pager_haspage in swap_pager_haspage().
It currently just says 0 pages ahead/behind.
4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
via a much more general mechanism that could also be used for disk
striping of regular filesystems.
5) Do something to improve the architecture of vm_object_collapse(). The
fact that it makes calls into the swap pager and knows too much about
how the swap pager operates really bothers me. It also doesn't allow
for collapsing of non-swap pager objects ("unnamed" objects backed by
other pagers).
that call vnode_pager_alloc() so that a failure return can be dealt with.
This fixes a panic seen on NFS clients when a file being opened is deleted
on the server before the open completes.
syscall to allow applications linked against their libc's uname() to
work. Netscape 1.1N being a prime example, which prints:
"uname() failed. cant tell what system we're running on".
This change is a little ugly, but that's mainly because of the "interesting"
semantics of the BSDI extension.
Since ogetkerninfo() is only enabled by COMPAT_43, Netscape will only
be affected on kernels with that option (eg: "GENERIC")
Reviewed by: davidg
might not be handled by the same FS as the directory (e.g. special device
files)...so it must be special-cased. This bug is seen when doing
"ln /dev/console /dev/foo" or equivilent and first appeared after I fixed
the argument order of VOP_LINK. YUCK! There really needs to be a way of
specifying what vp to use in the VCALL; doing this could fix the strategy
and bwrite special-cases, too.
2) Removed unnecessary vm_object_lookup()/pager_cache(object, TRUE) pairs
after vnode_pager_alloc() calls - the object is already guaranteed to be
persistent.
3) Removed some gratuitous casts.
VOP_CLOSE() takes `F' (file) flags, not `IO' flags. At least that's
what close() passes. I previously fixed ttylclose() to check
FNONBLOCK instead of IO_NDELAY. This broke the call from vclean()
and cleaning of ptys sometimes deadlocked.
when syscons stops mapping the console to minor MAXCONS. There is
usually no corresponding device in /dev, and the correct device has
minor 0.
cons.c:
Initialize cn_tty properly, so that CPU_CONSDEV can work.
Comment about too many variants of the console tty pointer.
machdep.c:
Return device NODEV and not error EFAULT when there is no console device.
