The current vnode layout is not smp-friendly by having frequently read data
avoidably sharing cachelines with very frequently modified fields. In
particular v_iflag inspected for VI_DOOMED can be found in the same line with
v_usecount. Instead make it available in the same cacheline as the v_op, v_data
and v_type which all get read all the time.
v_type is avoidably 4 bytes while the necessary data will easily fit in 1.
Shrinking it frees up 3 bytes, 2 of which get used here to introduce a new
flag field with a new value: VIRF_DOOMED.
Reviewed by: kib, jeff
Differential Revision: https://reviews.freebsd.org/D22715
1. replace hand-rolled macros for operation type with enum
2. unlock the vnode in vput itself, there is no need to branch on it. existence
of VPUTX_VPUT remains significant in that the inactive variant adds LK_NOWAIT
to locking request.
3. remove the useless v_usecount assertion. few lines above the checks if
v_usecount > 0 and leaves. should the value be negative, refcount would fail.
4. the CTR return vnode %p to the freelist is incorrect as vdrop may find the
vnode with holdcnt > 1. if the like should exist, it should be moved there
5. no need to error = 0 for everyone
Reviewed by: kib, jeff (previous version)
Differential Revision: https://reviews.freebsd.org/D22718
As mandated by POSIX. Also clarify the kill(2) manpage.
While there, restructure the code in killpg1() to use helper which
keeps overall state of the process list iteration in the killpg1_ctx
structued, later used to infer the error returned.
Reported by: amdmi3
Reviewed by: jilles
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D22621
Use the power of variable to avoid spelling out source and generated
files too many times. The previous Makefiles were hard to read, hard to
edit, and badly formatted.
Reviewed by: kevans, emaste
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D22714
Two changes to EPOCH_TRACE:
(1) add a sysctl to surpress the backtrace from epoch_trace_report().
Sometimes the log line for the recursion is enough and the
backtrace massively spams the console.
(2) In order to be able to go without the backtrace do not only
print where the previous occurance happened, but also where
the current one happens. That way we have file:line information
for both and can look at them without the need for getting line
numbers from backtrace and a debugging tool.
Reviewed by: glebius
Sponsored by: Netflix (originally)
Differential Revision: https://reviews.freebsd.org/D22641
First, this removes a spurious difference compared to rw locks.
More importantly though this avoids a trip through sleepq code if the lock
happens to be caught in this state.
The mbuf zones were explicitly specifying the uma trash procedures on
zcreate, conditionally on INVARIANTS, because that used to be necessary
in order to get use-after-free checking for uma zones with non-empty
constructors or destructors. After r355137 uma automatically invokes
the trash constructor and destructor as long as no init and fini are
specified. This now allows the mbuf zones to pass their constructors
and destructors without needing to add on the uma trash procedures
conditionally.
Reviewed by: cem, jhb, markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22583
- Use ustringp for the location of the argv and environment strings
and allow destp to travel further down the stack for the stackgap
and auxv regions.
- Update the Linux copyout_strings variants to move destp down the
stack as was done for the native ABIs in r263349.
- Stop allocating a space for a stack gap in the Linux ABIs. This
used to hold translated system call arguments, but hasn't been used
since r159992.
Reviewed by: kib
Tested on: md64 (amd64, i386, linux64), i386 (i386, linux)
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D22501
the vnode, logical block number, and size of data block that is
being requested. They then use the VOP_BMAP function to calculate
the mapping from logical block number to physical block number from
which to access the data. This change expands the interface to also
pass the physical block number in cases where the VOP_MAP function
may no longer work, for example when a file is being truncated.
No functional change.
Reviewed by: kib
Tested by: Peter Holm
Sponsored by: Netflix
Generally, it's preferred that an application fork/setsid if it doesn't want
to keep its controlling TTY, but it could be that a debugger is trying to
steal it instead -- so it would hook in, drop the controlling TTY, then do
some magic to set things up again. In this case, TIOCNOTTY is quite handy
and still respected by at least OpenBSD, NetBSD, and Linux as far as I can
tell.
I've dropped the note about obsoletion, as I intend to support TIOCNOTTY as
long as it doesn't impose a major burden.
Reviewed by: bcr (manpages), kib
Differential Revision: https://reviews.freebsd.org/D22572
The previously used quiesce_all_cpus walks all CPUs and waits until curthread
can run on them. Even on contemporary machines this becomes a significant
problem under load when it can literally take minutes for the operation to
complete. With the patch the stall is normally less than 1 second.
Reviewed by: kib, jeff (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21740
A variant of this facility was already used by rmlocks where IPIs would
enforce ordering.
This allows to elide fences where they are rarely needed and the cost of
IPI (should it be necessary) is cheaper.
Reviewed by: kib, jeff (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21740
This allows bumping threadcount without taking the global devmtx lock.
In particular this eliminates contention on said lock while using bhyve
with multiple vms.
Reviewed by: kib
Tested by: markj
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D22548
We already assert the lock is held later during tty_rel_free(), but it is
arguably good form to clarify locking expectations here as well at the
top-level that other drivers use.
vn_open_cred() assumes that it is called from the top-level of a VFS
syscall. Writers must call bwillwrite() before locking any VFS
resource to wait for cleanup of dirty buffers.
ZFS getextattr() and setextattr() VOPs do call vn_open_cred(), which
results in wait for unrelated buffers while owning ZFS vnode lock (and
ZFS does not use buffer cache). VN_OPEN_INVFS allows caller to skip
bwillwrite.
Note that ZFS is still incorrect there, because it starts write on an
mp and locks a vnode while holding another vnode lock.
Reported by: Willem Jan Withagen <wjw@digiware.nl>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The use of the uma trash procedures is automatic, there's no need to
pass them explicitly here.
Reviewed by: markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22582
tty_pts.c relies on sys/tty.h for sys/mutex.h. Include it directly instead
of relying on this pollution to ease the diff for anyone that wants to try
converting the tty lock to anything other than a mutex.
union members in vm_page.h to store the zone and slab. Remove some nearby
dead code.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D22564
There are two classes of rm lock, one "sleepable" and one not. But even
a "sleepable" rm lock is only sleepable in write mode, and is
non-sleepable when taken in read mode.
Warn about sleepable rm locks in read mode as non-sleepable locks. Do
this by defining a new lock operation flag, LOP_NOSLEEP, to indicate
that a lock is non-sleepable despite what the LO_SLEEPABLE flag would
indicate, and defining a new witness lock instance flag, LI_SLEEPABLE,
to track the product of LO_SLEEPABLE and LOP_NOSLEEP on the lock
instance.
Reviewed by: markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22527
. entries are never created and .. can reuse existing entries,
meaning the early count bump is both spurious and leading to
overcounting in certain cases.
The debugger like truss(1) depends on the wait(2) syscall. This syscall
waits for ALL children. When it is waiting for ALL child's the children
created by process descriptors are not returned. This behavior was
introduced because we want to implement libraries which may pdfork(1).
The behavior of process descriptor brakes truss(1) because it will
not be able to collect the status of processes with process descriptors.
To address this problem the status is returned to parent when the
child is traced. While the process is traced the debugger is the new parent.
In case the original parent and debugger are the same process it means the
debugger explicitly used pdfork() to create the child. In that case the debugger
should be using kqueue()/pdwait() instead of wait().
Add test case to verify that. The test case was implemented by markj@.
Reviewed by: kib, markj
Discussed with: jhb
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D20362
Several sysctl sysctls output to a user buffer while holding a
non-sleepable lock that protects the sysctl topology. They need to wire
the output buffer, or else they may try to sleep on a page fault.
Reviewed by: cem, markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22528
Record as much bits from curthread into busy_lock as fits. Low bits
for struct thread * representation are zero due to struct and zone
alignment, and they leave space for busy flags (perhaps except
statically allocated thread0). Upper bits are not very interesting
for assert, and in most practical situations recorded value should
allow to manually identify the owner with certainity.
Assert that unbusy is performed by the owner, except few places where
unbusy is done in io completion handler. For this case, add
_unchecked variants of asserts and unbusy primitives.
Reviewed by: markj (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D22298
Add a warning when a device registers with devfs and requests
D_NEEDGIANT. The warning says the device will go away before
13.0. This is needed to flush out the devices in the tree that are
still Giant locked. This warning, or some variant of it, should have
gone into the tree a long time ago...
The intention is to require all devices be converted to not use
automatic giant in this way, or remove any such devices that remain
that we don't have the hardware to test a conversion of.
kbd so far is the only device that can't leave the tree, yet needs
something sensible done to avoid the auto giant lock (even if it is
just doing the wrapping itself). There may be others added to this
list... Any discussions of this topic will take place on arch@.
Add explicit SI_SUB_EPOCH, after SI_SUB_TASKQ and before SI_SUB_SMP
(EARLY_AP_STARTUP). Rename existing "SI_SUB_TASKQ + 1" to SI_SUB_EPOCH.
epoch(9) consumers cannot epoch_alloc() before SI_SUB_EPOCH:SI_ORDER_SECOND,
but likely should allocate before SI_SUB_SMP. Prior to this change,
consumers (well, epoch itself, and net/if.c) just open-coded the
SI_SUB_TASKQ + 1 order to match epoch.c, but this was fragile.
Reviewed by: mmacy
Differential Revision: https://reviews.freebsd.org/D22503
Arm64 doesn't define the bus_space_set_multi_stream and
bus_space_set_region_stream functions. Don't try to define them there.
Sponsored by: DARPA, AFRL
Update the NetBSD Kernel Concurrency Sanitizer (KCSAN) runtime to work in
the FreeBSD kernel. It is a useful tool for finding data races between
threads executing on different CPUs.
This can be enabled by enabling KCSAN in the kernel config, or by using the
GENERIC-KCSAN amd64 kernel. It works on amd64 and arm64, however the later
needs a compiler change to allow -fsanitize=thread that KCSAN uses.
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D22315
