change the mountlist CIRCLEQ into a TAILQ

don't produce different output if we are super user.

provide a root entry if one was not found.

PR/45700: use dostatvfs instead of grabbing the latest cached copy of
struct statvfs from the mount point, so that chroot is handled properly.

PR# kern/45021: Please support /emul/linux/proc/version

Add /proc/version for procfs with -o linux. The version reported depends
on the emulation type of the calling process:

$ cat /proc/version
Ne

PR# kern/45021: Please support /emul/linux/proc/version

Add /proc/version for procfs with -o linux. The version reported depends
on the emulation type of the calling process:

$ cat /proc/version
NetBSD version 5.99.55 (netbsd@localhost) (gcc version 4.1.3 20080704 prerelease (NetBSD nb2 20081120)) NetBSD 5.99.55 (GENERIC) #39: Sun Sep 4 09:10:05 EDT 2011

$ /emul/linux/bin/cat /proc/version
Linux version 2.6.18 (linux@localhost) (gcc version 4.1.3 20080704 prerelease (NetBSD nb2 20081120)) #0 Wed Mar 3 03:03:03 PST 2010

$ /emul/linux32/bin/cat /proc/version
Linux version 2.6.18 (linux32@localhost) (gcc version 4.1.3 20080704 prerelease (NetBSD nb2 20081120)) #0 Wed Mar 3 03:03:03 PST 2010

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both LINUX_USRSTACK32 and USRSTACK32 need to be defined for linux32

Move counting of faults, traps, intrs, soft[intr]s, syscalls, and nswtch
from uvmexp to per-cpu cpu_data and move them to 64bits. Remove unneeded
includes of <uvm/uvm_extern.h> and/or <uvm/uvm.h>.

Avoid leaking pages. Fixes PR 42053 from SHIMIZU Ryo.

this change was somehow missed.

merge christos-time_t

Rename specfs_lock as device_lock and move it from specfs to devsw.
Relaxes kernel dependency on vfs.

Kill devsw_lock and just use specfs_lock. The two would need merging
in order to prevent unload of modules when a device that they provide
is still open.

PR kern/38141 lookup/vfs_busy acquire rwlock recursively

Simplify the mount locking. Remove all the crud to deal with recursion on
the mount lock, and crud to deal with unmount as another weirdo loc

PR kern/38141 lookup/vfs_busy acquire rwlock recursively

Simplify the mount locking. Remove all the crud to deal with recursion on
the mount lock, and crud to deal with unmount as another weirdo lock.

Hopefully this will once and for all fix the deadlocks with this. With this
commit there are two locks on each mount:

- krwlock_t mnt_unmounting. This is used to prevent unmount across critical
sections like getnewvnode(). It's only ever read locked with rw_tryenter(),
and is only ever write locked in dounmount(). A write hold can't be taken
on this lock if the current LWP could hold a vnode lock.

- kmutex_t mnt_updating. This is taken by threads updating the mount, for
example when going r/o -> r/w, and is only present to serialize updates.
In order to take this lock, a read hold must first be taken on
mnt_unmounting, and the two need to be held across the operation.

One effect of this change: previously if an unmount failed, we would make a
half hearted attempt to back out of it gracefully, but that was unlikely to
work in a lot of cases. Now while an unmount that will be aborted is in
progress, new file operations within the mount will fail instead of being
delayed. That is unlikely to be a problem though, because if the admin
requests unmount of a file system then s(he) has made a decision to deny
access to the resource.

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PR kern/38135 vfs_busy/vfs_trybusy confusion

The previous fix worked, but it opened a window where mounts could have
disappeared from mountlist while the caller was traversing it using
vfs_trybusy()

PR kern/38135 vfs_busy/vfs_trybusy confusion

The previous fix worked, but it opened a window where mounts could have
disappeared from mountlist while the caller was traversing it using
vfs_trybusy(). Fix that.

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kern/38135 vfs_busy/vfs_trybusy confusion

The symptom was that sometimes file systems would occasionally not appear
in output from 'df' or 'mount' if the system was busy. Resolution:

- Make mount l

kern/38135 vfs_busy/vfs_trybusy confusion

The symptom was that sometimes file systems would occasionally not appear
in output from 'df' or 'mount' if the system was busy. Resolution:

- Make mount locks work somewhat like vm_map locks.
- vfs_trybusy() now only fails if the mount is gone, or if someone is
unmounting the file system. Simple contention on mnt_lock doesn't
cause it to fail.
- vfs_busy() will wait even if the file system is being unmounted.

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Merge proc::p_mutex and proc::p_smutex into a single adaptive mutex, since
we no longer need to guard against access from hardware interrupt handlers.

Additionally, if cloning a process with CLONE_S

Merge proc::p_mutex and proc::p_smutex into a single adaptive mutex, since
we no longer need to guard against access from hardware interrupt handlers.

Additionally, if cloning a process with CLONE_SIGHAND, arrange to have the
child process share the parent's lock so that signal state may be kept in
sync. Partially addresses PR kern/37437.

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Network protocol interrupts can now block on locks, so merge the globals
proclist_mutex and proclist_lock into a single adaptive mutex (proc_lock).
Implications:

- Inspecting process state requires

Network protocol interrupts can now block on locks, so merge the globals
proclist_mutex and proclist_lock into a single adaptive mutex (proc_lock).
Implications:

- Inspecting process state requires thread context, so signals can no longer
be sent from a hardware interrupt handler. Signal activity must be
deferred to a soft interrupt or kthread.

- As the proc state locking is simplified, it's now safe to take exit()
and wait() out from under kernel_lock.

- The system spends less time at IPL_SCHED, and there is less lock activity.

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PR kern/37706 (forced unmount of file systems is unsafe):

- Do reference counting for 'struct mount'. Each vnode associated with a
mount takes a reference, and in turn the mount takes a reference

PR kern/37706 (forced unmount of file systems is unsafe):

- Do reference counting for 'struct mount'. Each vnode associated with a
mount takes a reference, and in turn the mount takes a reference to the
vfsops.
- Now that mounts are reference counted, replace the overcomplicated mount
locking inherited from 4.4BSD with a recursable rwlock.

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procfs_douptime: simply use microuptime() instead of a mysterious calculation.

procfs_docpustat: g/c a write-only variable.

Revision 1.42 was lost. Pointed out by Nicolas Joly:

This was using mutex_exit where mutex_enter was required.

report the proper stack size on 32 bit emulations.

Merge from vmlocking:

- pool_cache changes.
- Debugger/procfs locking fixes.
- Other minor changes.

This was using mutex_exit where mutex_enter was required.

Merge from vmlocking:

- Split vnode::v_flag into three fields, depending on field locking.
- simple_lock -> kmutex in a few places.
- Fix some simple locking problems.