in connection with Marvell based SATA->PATA dongles.
The problem was caused by a combination of things working
together to make it hard to spot...
The ATA driver has always started the ATA command, then build
the SG list for DMA and then finally started the DMA engine.
While this is according to specs, it poses a potential
problem as some controllers apparently do not allow for unlimitted
time between starting the ATA command and starting the DMA engine.
At about the same time as ATAng was committed there were lots
of other changes applied, some of which was locking in parts
that causes the busdma load functions to take significantly
longer to load the SG list.
This pushed the time spent between starting the ATA command and
starting the DMA engine over the hill for some controllers
(especially the Silicon Image DS3112a) and caused what looked
like lost interrupts.
The solution is to get all the SG list work or rather all
busdma related stuff done before we even try to start anything.
This has the nice side effect of seperating busdma out the
way it should be, so the working of the ATA machinery is not
cluttered up with busdma droppings, making the code easier
to read and understand.
sysctl that a given variable is tunable.
Also added is CTLFLAG_RDTUN, which is CTLFLAG_RD|CTLFLAG_TUN; TUN does
not always imply read-only, so RDTUN should be used where RD was used
before.
for dev_strategy() use.
Retire bio_driver[12] (aliases for b_io.bio_driver[12]) these fields are
reserved for device driver use and can as such never have any interest
in the buf end of things.
- Return NULL instead of returning memory outside of the stackgap
in stackgap_alloc() (FreeBSD-SA-00:42.linux)
- Check for stackgap_alloc() returning NULL in svr4_emul_find(),
and clean_pipe().
- Avoid integer overflow on large nfds argument in svr4_sys_poll()
- Reject negative nbytes argument in svr4_sys_getdents()
- Don't copy out past the end of the struct componentname
pathname buffer in svr4_sys_resolvepath()
- Reject out-of-range signal numbers in svr4_sys_sigaction(),
svr4_sys_signal(), and svr4_sys_kill().
- Don't malloc() user-specified lengths in show_ioc() and
show_strbuf(), place arbitrary limits instead.
- Range-check lengths in si_listen(), ti_getinfo(), ti_bind(),
svr4_do_putmsg(), svr4_do_getmsg(), svr4_stream_ti_ioctl().
Some fixes obtain from OpenBSD.
pick up the DEVFS inode number from the dev_t and find our directory
entry from that, we don't need to scan the directory to find it.
This also solves an issue with on-demand devices in subdirectories.
Submitted by: cognet
by libguile that needs to know the base of the RSE backing store. We
currently do not export the fixed address to userland by means of a
sysctl so user code needs to hardcode it for now. This will be revisited
later.
The RSE backing store is now at the bottom of region 4. The memory stack
is at the top of region 4. This means that the whole region is usable
for the stacks, giving a 61-bit stack space.
Port: lang/guile (depended of x11/gnome2)
chain passed into dc_encap, which dc_start was unaware of. This caused
the old (now invalid) mbuf to be passed to BPF_MTAP.
Spotted by: Kenjiro Cho <kjc@csl.sony.co.jp>
is non-free. (More checks can/should be added in the future.)
Use M_ASSERTVALID in BPF_MTAP so that we catch when freed mbufs are
passed in, even if no bpf listeners are active.
Inspired by a bug in if_dc caught by Kenjiro Cho.
rijndael_blockDecrypt() as both input and output.
This property is important because inside rijndael we can get away
with allocating just a 16 byte "work" buffer on the stack (which
is very cheap), whereas the calling code would need to allocate the
full sized buffer, and in all likelyhood would have to do so with
an expensive malloc(9).
table, acquiring the necessary locks as it works. It usually returns
two references to the new descriptor: one in the descriptor table
and one via a pointer argument.
As falloc releases the FILEDESC lock before returning, there is a
potential for a process to close the reference in the file descriptor
table before falloc's caller gets to use the file. I don't think this
can happen in practice at the moment, because Giant indirectly protects
closes.
To stop the file being completly closed in this situation, this change
makes falloc set the refcount to two when both references are returned.
This makes life easier for several of falloc's callers, because the
first thing they previously did was grab an extra reference on the
file.
Reviewed by: iedowse
Idea run past: jhb
to the object's type field and the call to vm_pageout_flush() are
synchronized.
- The above change allows for the eliminaton of the last parameter
to vm_pageout_flush().
- Synchronize access to the page's valid field in vm_pageout_flush()
using the containing object's lock.
- Specifying VM_MAP_WIRE_HOLESOK should not assume that the start
address is the beginning of the map. Instead, move to the first
entry after the start address.
- The implementation of VM_MAP_WIRE_HOLESOK was incomplete. This
caused the failure of mlockall(2) in some circumstances.
Use EP_{READ,WRITE}{,_MULTI}_{1,2,4} instead. I've had several people
submit patches like this over the years of varying qualities, markm
being the last. The names were chosen in consulation with mdodd on
irc.
I've tested this with only PCMCIA cards: 3CCE589EC and 3CCSH572BT.
I've not tried with my more extensive ISA, EISA and cbus collection.
Reviewed by: mdodd
the point where it being a macro is no longer sensible, and it will
only be more so in days to come.
BIO_STRATEGY() is now only used from DEV_STRATEGY() and should not
be used directly anymore.
Put the contents of both in the new function dev_strategy() and
make DEV_STRATEGY() call that function.
In addition, this allows us to make the rather magic bufdonebio()
helper function static.
This alse saves hunderedandsome bytes of code in a typical kernel.
Though this is still incomplete and has some missing features such as
exclusive login and event notification, it may be enough for someone
who wants to play with it.
This driver is supposed to work with firewire(4), targ(4) of CAM(4)
and scsi_target(8) which can be found in /usr/share/example/scsi_target.
This driver doesn't require sbp(4) which implements initiator mode.
Sample configuration:
Kernel: (you can use modules as well)
device firewire
device scbus
device targ
device sbp_targ
After reboot:
# mdconfig -a -t malloc -s 10m
md0
# scsi_target 0:0:0 /dev/md0
(Assuming sbp_targ0 on scbus0)
You should find the 10MB HDD on FreeBSD/MacOS X/WinXP or whatever connected
to the target using FireWire.
Manpage is not finished yet.
- Change type of target->luns to allocate an array of LUNs dynamically.
This allows targets to change their number of LUNs after each bus reset.
- Serialize ORB POINTER command for each LUN.
- Improve debug messages.
definition structure. Define one flag, CN_FLAG_NODEBUG, which
indicates the console driver cannot be used in the context of the
debugger. This may be used, for example, if the console device
interacts with kernel services that cannot be used from the
debugger context, such as the network stack. These drivers are
skipped over for calls to cn_checkc() and cn_putc(), and the
calling function simply moves on to the next available console.
- Correct the logic for the AIF array index pointers so that correct slot is
always looked at.
- Copy the full FIB payload size when copying AIF's, not just the first 64
bytes.
Thanks to Mirapoint, Inc, for pointing these problems out and offering a
solution.
a fair bit of difference to the power consumption and lets my cpu cool
down enough for the temperature sensitive fan controller to completely
stop the cpu fan at times.
halt state that minimizes power consumption while still preserving
cache and TLB coherency. Halting the processor is not conditional at
this time. Tested with UP and SMP kernels.
address has been changed when PFIL_HOOKS is enabled and, if it has,
arrange for the proper action by ip*_forward.
Submitted by: Pyun YongHyeon
Supported by: FreeBSD Foundation
address has been changed when PFIL_HOOKS is enabled and, if it has,
arrange for the proper action by ip*_forward.
Supported by: FreeBSD Foundation
Submitted by: Pyun YongHyeon
Xcpustop(). %es is used in at least the call to savectx() when savectx()
calls bcopy(), so not loading it was fatal if a stop IPI interrupts
user mode.
This reduces bugs starting and stopping CPUs for debuggers. CPUs are
stopped mainly in kdb_trap() and cpu_reset(). At reset time there is
a good chance that all the CPUs are in the kernel, so the bug was
probably harmless then.
classes and if a method is not found in a given class, its base classes
are searched (in the order they were declared). This search is recursive,
i.e. a method may be define in a base class of a base class.
* Change the kobj method lookup algorithm to one which is SMP-safe. This
relies only on the constraint that an observer of a sequence of writes
of pointer-sized values will see exactly one of those values, not a
mixture of two or more values. This assumption holds for all processors
which FreeBSD supports.
* Add locking to kobj class initialisation.
* Add a simpler form of 'inheritance' for devclasses. Each devclass can
have a parent devclass. Searches for drivers continue up the chain of
devclasses until either a matching driver is found or a devclass is
reached which has no parent. This can allow, for instance, pci drivers
to match cardbus devices (assuming that cardbus declares pci as its
parent devclass).
* Increment __FreeBSD_version.
This preserves the driver API entirely except for one minor feature used
by the ISA compatibility shims. A workaround for ISA compatibility will
be committed separately. The kobj and newbus ABI has changed - all modules
must be recompiled.
rounding errors. This was the source of the majority of the
interactivity problems. Reintroduce the old algorithm and its XXX.
- Up the interactivity threshold to 30. It really could stand to be even
a tiny bit higher.
- Let the sleep and run time accumulate up to 5 seconds of history rather
than two. This helps stop XFree86 from becoming non-interactive during
bursts of activity.
trashed after being freed. This has caused several panics including
kern/42277 related to soft updates. Jim Kuhn tracked the problem
down to ipfw limit rule processing. In the expiry of dynamic rules,
it is possible for an O_LIMIT_PARENT rule to be removed when it still
has live children. When the children eventually do expire, a pointer
to the (long gone) parent is dereferenced and a count decremented.
Since this memory can, and is, allocated for other purposes (in the
case of kern/42277 an inodedep structure), chaos ensues. The offset
in question in inodedep is the offset of the 16 bit count field in
the ipfw2 ipfw_dyn_rule.
Submitted by: Jim Kuhn <jkuhn@sandvine.com>
Reviewed by: "Evgueni V. Gavrilov" <aquatique@rusunix.org>
Reviewed by: Ben Pfountz <netprince@vt.edu>
MFC after: 1 week
passes the fdidx from VOP_OPEN down.
This is for all I know the final API for this functionality, but
the locking semantics for messing with the filedescriptor from
the device driver are not settled at this time.
Discussed in from [FreeBSD-tech-jp 3396] to [FreeBSD-tech-jp 3407]
at FreeBSD-tech-jp@jp.freebsd.org.
NOTE: We must put ed_probe_SIC() function into if_ed_isa.c because
this is a bus dependent code. But the ed driver code is not
separated explicitly whether it is bus dependent or independent
now.
Refer to: http://plaza17.mbn.or.jp/~chi/myprog/FreeBSD/sicat.html
Submitted by: chi@bd.mbn.or.jp (Chiharu Shibata)
every page. If the source entry was read-only, one or more wired pages
could be in backing objects.
- vm_fault_copy_entry() should not set the PG_WRITEABLE flag on the page
unless the destination entry is, in fact, writeable.
elevated either due to priority propagation or because we're in the
kernel in either case, put us on the current queue so that we dont
stop others from using important resources. At some point the priority
elevations from sleeping in the kernel should go away.
- Remove an optimization in sched_userret(). Before we would only set
NEEDRESCHED if there was something of a higher priority available. This
is a trivial optimization and it breaks priority propagation because it
doesn't take threads which we may be blocking into account. Notice that
the thread which is blocking others gets up to one tick of cpu time before
we honor this NEEDRESCHED in sched_clock().
lock around a call to the original function. Make the timeout
function in callout_reset() use the wrapped function to avoid a
lock assertion panic.
Reviewed by: sam
Reported by: cgiordano@ids.net
sigreturn() ABI and the signal context on the stack.
Make the trapframe (and its shadows in the ucontext and sigframe etc)
8 bytes larger in order to preserve 16 byte stack alignment for the
following C code calls. I could have done some padding after the
trapframe was saved, but some of the C code still expects an argument of
'struct trapframe'. Anyway, this gives me a spare field that can be used
to store things like 'partial trapframe' status or something else in
the future.
The runtime impact is fairly small, *except* for threaded apps and things
that decode contexts and the signal stack (eg: cvsup binary). Signal
delivery isn't too badly affected because the kernel generates the
sigframe that sigreturn uses after the handler has been called.
The size of mcontext_t and struct sigframe hasn't changed. Only
the last few fields (sc_eip etc) got moved a little and I eliminated
a spare field. mc_len/sc_len did change location though so the
sanity checks there will still trap it.
- Make multicast work
- Fix (some of) the watchdog timeouts after card reset
- Add support for CE2, CEM28 and CEM33 cards
- General code cleanup
Any card that worked previously should still work, as well as a lot that
didn't.
The driver is not yet style(9) compliant; those changes are forthcoming,
once the functional changes are done.
PR: kern/50644
Reviewed by: imp
Approved by: imp
I changed. That is never a good sign.
1) only map 1 page at address zero, not 4096 pages
2) page 1 starts at address 4096 (PAGE_SIZE) not 4095 (PAGE_MASK). I
don't even want to think what the pte's looked like.
3) subtract the r/o page group start address from the end before
converting it to a count. Otherwise an extra page is mapped.
If you were affected by this, the symptoms of this was a hang at boot
after the spinner. Sorry folks. :-(
"You broke my laptop!" by: sam
accesses softc after it is freed. Use a different malloc type for
softc than the rest of the bus code to make it more clear when these
things happen that it is the driver that's at fault, not the bus code.
Suggested by: sam and/or phk (I think)
timeout would continue to happen: boom! Fix this[*] by timing out earlier.
[*] almost fixes the race on unload: wi_inquire could be running when
untimeout is called, and there's no way to know when it has actually
returned. This race is very rare and hard to lose.
Submitted by: scottl
seeded with arc4random rather than calling arc4random for each
packet. Note this is the same algorithm used to select the IV when
doing WEP on the host.
o don't grab the mutex at the top of ath_detach; it does nothing
useful
o deal with entry to ath_ioctl during detach to disable promiscuous
mode as a result of calling bpfdetach2: cannot call ath_init when
the device is marked invalid as the code isn't prepared to deal
with it (in particular by that time the hal reference may have
been yanked)
change ath_rate_ctl_reset to handle transition from station
mode to adhoc mode; was not resetting the initial xmit rate
causing outbound frames to be dicarded
use because a kernel thread is borrowing it. The borrowed page table
can change spontaneously, making any dependence on its continued use
subject to a race condition.
- _pmap_unwire_pte_hold() cannot use pmap_is_current(): If a change is
made to a page table page mapping for a borrowed page table, the TLB
must be updated.
In collaboration with: tegge
you on the current queue. In the future, it would be nice if priority
propagation could deterministicly pluck a thread off of the next queue
and put it on the current queue. Until then this hack stops us from
holding up our entire current queue, including interrupt handlers, while
a thread on the next queue is blocked while holding Giant.
- Inherit our pctcpu information from our parent.
- correct signedness mixups.
- log fix.
- preparation for 64bit sequence number.
introduce SA id (unique ID for SA - SPI is useless as duplicated
SPI is allowed)
- no need to malloc/free cksum buffer.
Obtained from: KAME
kqueue write events on a socket and you regularly create tons of pipes
which overwrites the structure causing a panic when removing the knote
from the list. If the peer has gone away (and it's a write knote), then
don't bother trying to remove the knote from the list.
Submitted by: Brian Buchanan and myself
Obtained from: nCircle
- Return NULL instead of returning memory outside of the stackgap
in stackgap_alloc() (FreeBSD-SA-00:42.linux)
- Check for stackgap_alloc() returning NULL in ibcs2_emul_find();
other calls to stackgap_alloc() have not been changed since they
are small fixed-size allocations.
- Replace use of strcpy() with strlcpy() in exec_coff_imgact()
to avoid buffer overflow
- Use strlcat() instead of strcat() to avoid a one byte buffer
overflow in ibcs2_setipdomainname()
- Use copyinstr() instead of copyin() in ibcs2_setipdomainname()
to ensure that the string is null-terminated
- Avoid integer overflow in ibcs2_setgroups() and ibcs2_setgroups()
by checking that gidsetsize argument is non-negative and
no larger than NGROUPS_MAX.
- Range-check signal numbers in ibcs2_wait(), ibcs2_sigaction(),
ibcs2_sigsys() and ibcs2_kill() to avoid accessing array past
the end (or before the start)
parameter in the read and write case dereferenced an unitialized
pointer and can't possibly ever have catched an actual invalid
argument.
This was apparently true for the read/write and getconf cases. The
latter does not even receive the paramter that is to be verified.
I'm surprised that this did not cause kernel panics, but it seems
that the uninitialized local variable happens to contain data that
may be used as a pointer to memory that satisfies the test condition.
Make the code work as intended by moving the test inside the switch
case where the pointer has been properly initialized.
Since the read and write case shared just about all code (except
for the single call to PCIB_READ_CONFIG resp. PCIB_WRITE_CONFIG) I
have merged both cases.
Noticed by: trhodes@FreeBSD.org (Tom Rhodes)
- Allocate storage for uap->msg always because it is copyin()'ed in
native sendmsg().
- Convert sockopt level from Linux to FreeBSD after native recvmsg() calling.
- Some cleanups.
Tested with: Oracle 9i shared server connection mode.
MFC after: 1 week
o correct recursive locking when polling and in em_82547_move_tail
o destroy mutex on detach
o add EM_LOCK_ASSERT and similar macros for creating+deleteing the mtx
Submitted by: Daniel Eischen <eischen@vigrid.com>
beasts which are reported to exist in both Atmel and Prism2 flavours. In
particular, Itronix branded laptops have the Atmel part with an Intersil
radio.
Obtained from: NetBSD
from UWX_REG_MUMBLE to UWX_REG_AR_MUMBLE. Compatibility defines are
present in libuwx. Change the names here so that we don't depend on
compatibility defines.
Note that there's now an UWX_REG_PFS and an UWX_REG_AR_PFS and the
former is not a compatibility define for the latter AFAICT. Change
to UWX_REG_AR_PFS as that seems to be the one we need to handle.
all the fixes locally applied and submitted to the author. Not
included in BETA 5, but part of this import are:
o FreeBSD specific ifdefs to make this compile within a kernel.
These are limited to include directives and defines.
o Removal of unused variables, proper casts and initializations
to allow building with -Werror. This happens in code so has a
higher chance of causing future import conflicts but not enough
to worry about it.
I'm especially thankful that the author accepted the change to
replace DISABLE_TRACE with UWX_TRACE_ENABLE so that we can use it
in kernel config files without nasty mappings or indirections as
that would make the integration less perfect. Thanks Cary!
an uninitialized sysctl_ctx, using flag DA_FLAG_SCTX_INIT. This
prevents a panic encoutered with some umass units that probe correctly
but fail to attach. Same problem, and same fix, as scsi_cd.c rev. 1.86.
Reviewed by: njl, ken
pmap_copy_page() et al. to accept a vm_page_t rather than a physical
address. Also, this change will facilitate locking access to the vm page's
valid field.
has been initialized.
(cdsysctlinit): Set flag CD_FLAG_SCTX_INIT after sysctl_ctx has been
initialized.
This resolves a panic encountered when a cd drive is sucessfully probed
but fails to attach.
Reviewed by: ken
o minor optimization of cardbus_cis processing. Remove a bunch of generic
entries that are handled by generic.
o no longer need the card_get_type stuff.
This MIB specifies how many bus resets should be observed before the
lost device entry is removed. The default value is 3.
You can set this value to 0 if you want a SBP device to be detached from CAM
layer as soon as the device is physically detached like USB.
routine of its own, and allows us to move the indentation back two
layers making the code more readable.
delete a prototype that should have been killed years ago in pccardvar.h.
# adding quirks here is way harder than it needs to be. :-(
In unodered excution case, we cannot detect link-chain end only
by prev == NULL if lastest ORB is executed earlyer than the former
ORBs. Use ORB_LINK_DEAD flag for this case.
- Don't reset agent for management ORB.
- Improve debug messages.
Spotted by: sbp target mode
a long-time bug: vm_pager_get_pages() assumes that m[reqpage] contains a
valid page upon return from pgo_getpages(). In the case of the device
pager this page has been freed and replaced by a fake page. The fake page
is properly inserted into the vm object but m[reqpage] is left pointing
to a freed page. For now, update m[reqpage] to point to the fake page.
Submitted by: tegge
caused snapshot related problems.
- The vp can not be NULL here or we would panic in vfs_bio_awrite(). Stop
confusing the logic by checking for it in several places.
Submitted by: kirk and then rototilled by me to remove vp == NULL checks.
for 21143 based cards which use SIA mode.
This fixes 10mbit mode for ZNYX ZX346Q cards and other
21143 based cards.
PR: 32118
Submitted by: Rene de Vries <rene@tunix.nl>
Geert Jan de Groot <GeertJan.deGroot@tunix.nl>
Obtained from: BSDI
MFC after: 2 weeks
VOP_INACTIVE routines need not worry about their vnode getting
recycled if they block. Remove the code from nfs_inactive() that
used vget() to get an extra vnode reference that was held during
the nfs_vinvalbuf() call.
so make the code slightly more uniform. The vnode lock is acquired in
all cases and now the only difference between VCHR and other is we
call UFS_UPDATE instead of VOP_FSYNC().
Use pre-emption detection to avoid the need for wiring a userland buffer
when copying opaque data structures.
sysctl_wire_old_buffer() is now a no-op. Other consumers of this
API should use pre-emption detection to notice update collisions.
vslock() and vsunlock() should no longer be called by any code
and should be retired in subsequent commits.
Discussed with: pete, phk
MFC after: 1 week
go away in due course. Involuntary pre-emption means that we can't count
on wiring of pages alone for consistency when performing a SYSCTL_OUT()
bigger than PAGE_SIZE.
Discussed with: pete, phk
- Slightly rewrite the fsync loop to be more lock friendly. We must
acquire the vnode interlock before dropping the mnt lock. We must
also check XLOCK to prevent vclean() races.
- Use LK_INTERLOCK in the vget() in ffs_sync to further prevent vclean()
races.
- Use a local variable to store the results of the nvp == TAILQ_NEXT
test so that we do not access the vp after we've vrele()d it.
- Add an XXX comment about UFS_UPDATE() not being protected by any lock
here. I suspect that it should need the VOP lock.
LK_RETRY either, we don't want this vnode if it turns into another.
- Remove the code that checks the mount point after acquiring the lock
we are guaranteed to either fail or get the vnode that we wanted.
- In vtryrecycle() try to vgonel the vnode if all of the previous checks
passed. We won't vgonel if someone has either acquired a hold or usecount
or started the vgone process elsewhere. This is because we may have been
removed from the free list while we were inspecting the vnode for
recycling.
- The VI_TRYLOCK stops two threads from entering getnewvnode() and recycling
the same vnode. To further reduce the likelyhood of this event, requeue
the vnode on the tail of the list prior to calling vtryrecycle(). We can
not actually remove the vnode from the list until we know that it's
going to be recycled because other interlock holders may see the VI_FREE
flag and try to remove it from the free list.
- Kill a bogus XXX comment. If XLOCK is set we shouldn't wait for it
regardless of MNT_WAIT because the vnode does not actually belong to
this filesystem.
purge, the purge in vclean, and the filesystems purge, we had 3 purges
per vnode.
- Move the insmntque(vp, 0) to vclean() so that we may remove it from the
two vgone() functions and reduce the number of lock operations required.
whether or not the sync failed. This could potentially get set between
the time that we VOP_UNLOCK and VI_LOCK() but the race would harmelssly
lead to the sync being delayed by an extra 30 seconds. If we do not move
the vnode it could cause an endless loop if it continues to fail to sync.
- Use vhold and vdrop to stop the vnode from changing identities while we
have it unlocked. Other internal vfs lists are likely to follow this
scheme.
- Create a new function, vgonechrl(), which performs vgone for an in-use
character device. Move the code from vflush() that did this into
vgonechrl().
- Hold the xlock across the entirety of vgonel() and vgonechrl() so that
at no point will an invalid vnode exist on any list without XLOCK set.
- Move the xlock code out of vclean() now that it is in the vgone*()
functions.
work in, but we had it mapped read-only. While this has always been the
case, the PG_PS enable hack hid it and the apm bios code ended up taking
advantage of it.
This is so that we may grab the interlock while still holding the
sync_mtx. We have to VI_TRYLOCK() because in all other cases the lock
order runs the other way.
- If we don't meet any of the preconditions, reinsert the vp into the
list for the next second.
- We don't need to panic if we fail to sync here because each FSYNC
function handles this case. Removing this redundant code also
simplifies locking.
will not actually be set even though we're calling sosetopt. sosetopt
calls down to a single ctloutput function if the name or level is
implemented by a specific protocol.
Submitted by: pete@isilon.com
fail. Remove the panic from that case and document why it might fail.
- Document the reason for calling cache_purge() on a newly created vnode.
- In insmntque() order the operations so that we can call mtx_unlock()
one fewer times. This makes the code somewhat clearer as well.
- Add XXX comments in sched_sync() and vflush().
- In vget(), do not sleep while waiting for XLOCK to clear if LK_NOWAIT is
set.
- In vclean() we don't need to acquire a lock around a single TAILQ_FIRST
call. It's ok if we race here, the vinvalbuf will just do nothing.
- Increase the scope of the lock in vgonel() to reduce the number of lock
operations that are performed.
we release the mntvnode_mtx.
- Call vgonel() directly instead of going through vrecycle() since we own
the interlock now.
- Remove a few cases where we locked the interlock just so that we could
call VOP_UNLOCK with interlock held.
mntvnode_mtx.
- Use a local variable to store the results of the test to see if the
next vnode on the mount list has changed. This is so that we no longer
acess the vnode after we vput() it.
