kern: restore signal mask before ast() for pselect/ppoll

It's possible to take a signal after pselect/ppoll have set their return
value, but before we actually return to userland. This results in
t

kern: restore signal mask before ast() for pselect/ppoll

It's possible to take a signal after pselect/ppoll have set their return
value, but before we actually return to userland. This results in
taking a signal without reflecting it in the return value, which weakens
the guarantees provided by these functions.

Switch both to restore the signal mask before we would deliver signals
on return to userland. If a signal was received after the wait was
over, then we'll just have the signal queued up for the next time it
comes unblocked. The modified signal mask is retained if we were
interrupted so that ast() actually handles the signal, at which point
the signal mask is restored.

des@ has a test case demonstrating the issue in D47738 which will
follow.

Note for MFC: TDA_PSELECT is a KBI break, we should just inline
ast_sigsuspend() in pselect/ppoll for stable branches. It's not exactly
the same, but it will be close enough.

Reported by: des
Reviewed by: des (earlier version), kib
Sponsored by: Klara, Inc.
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D47741

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kcmp_pget(): do not accept TIDs

Otherwise pget() might still look up and hold the current process.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 days

kcmp_pget(): add an assert that we did not hold the current process

Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 days

ktrace: log genio events on failed write

Visibility into the contents of the buffer when a write(2) has failed
can be immensely useful in debugging IPC issues -- pushing this to
discuss the idea, or

ktrace: log genio events on failed write

Visibility into the contents of the buffer when a write(2) has failed
can be immensely useful in debugging IPC issues -- pushing this to
discuss the idea, or maybe an alternative where we can set a flag like
KTRFAC_ERRIO to enable it.

When a genio event is potentially raised after an error, currently we'll
just free the uio and return. However, such data can be useful when
debugging communication between processes to, e.g., understand what the
remote side should have grabbed before closing a pipe. Tap out the
entire buffer on failure rather than simply discarding it.

Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D43799

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kern: poll: tap out the pollfd array on successful return

We do this in kern_poll() to include freebsd32 but exclude the linux
compat layer. The ABI should be the same, but the POLL constants are
p

kern: poll: tap out the pollfd array on successful return

We do this in kern_poll() to include freebsd32 but exclude the linux
compat layer. The ABI should be the same, but the POLL constants are
probably different or should be assumed so.

Reviewed by: bapt, jhb
Differential Revision: https://reviews.freebsd.org/D44158

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Abstract UIO allocation and deallocation.

Introduce the allocuio() and freeuio() functions to allocate and
deallocate struct uio. This hides the actual allocator interface, so it
is easier to modify

Abstract UIO allocation and deallocation.

Introduce the allocuio() and freeuio() functions to allocate and
deallocate struct uio. This hides the actual allocator interface, so it
is easier to modify the sub-allocation layout of struct uio and the
corresponding iovec array.

Obtained from: CheriBSD
Reviewed by: kib, markj
MFC after: 2 weeks
Sponsored by: CHaOS, EPSRC grant EP/V000292/1
Differential Revision: https://reviews.freebsd.org/D43711

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kcmp(2): implement for generic file types

Reviewed by: brooks, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D43518

Add kcmp(2) kernel bits

This is based purely on reading the Linux kcmp(2) man page.
In addition to the Linux set of comparators, I also added KCMP_FILEOBJ to
compare underlying file' objects.

Teste

Add kcmp(2) kernel bits

This is based purely on reading the Linux kcmp(2) man page.
In addition to the Linux set of comparators, I also added KCMP_FILEOBJ to
compare underlying file' objects.

Tested by: manu
Reviewed by: brooks, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D43518

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sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl s

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

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sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

sockets: provide sousrsend() that does socket specific error handling

Sockets have special handling for EPIPE on a write, that was spread out
into several places. Treating transient errors is also

sockets: provide sousrsend() that does socket specific error handling

Sockets have special handling for EPIPE on a write, that was spread out
into several places. Treating transient errors is also special - if
protocol is atomic, than we should ignore any changes to uio_resid, a
transient error means the write had completely failed (see d2b3a0ed31e).

- Provide sousrsend() that expects a valid uio, and leave sosend() for
kernel consumers only. Do all special error handling right here.
- In dofilewrite() don't do special handling of error for DTYPE_SOCKET.
- For send(2), write(2) and aio_write(2) call into sousrsend() and remove
error handling for kern_sendit(), soo_write() and soaio_process_job().

PR: 265087
Reported by: rz-rpi03 at h-ka.de
Reviewed by: markj
Differential revision: https://reviews.freebsd.org/D35863

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AST: rework

Make most AST handlers dynamically registered. This allows to have
subsystem-specific handler source located in the subsystem files,
instead of making subr_trap.c aware of it. For inst

AST: rework

Make most AST handlers dynamically registered. This allows to have
subsystem-specific handler source located in the subsystem files,
instead of making subr_trap.c aware of it. For instance, signal
delivery code on return to userspace is now moved to kern_sig.c.

Also, it allows to have some handlers designated as the cleanup (kclear)
type, which are called both at AST and on thread/process exit. For
instance, ast(), exit1(), and NFS server no longer need to be aware
about UFS softdep processing.

The dynamic registration also allows third-party modules to register AST
handlers if needed. There is one caveat with loadable modules: the
code does not make any effort to ensure that the module is not unloaded
before all threads processed through AST handler in it. In fact, this
is already present behavior for hwpmc.ko and ufs.ko. I do not think it
is worth the efforts and the runtime overhead to try to fix it.

Reviewed by: markj
Tested by: emaste (arm64), pho
Discussed with: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D35888

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Add timespecvalid_interval macro and use it.

Reviewed by: jhb, imp (early rev)
Differential revision: https://reviews.freebsd.org/D34848
MFC after: 2 weeks

fd: rename fget*_locked to fget*_noref

This gets rid of the error prone naming where fget_unlocked returns with
a ref held, while fget_locked requires a lock but provides nothing in
terms of making

fd: rename fget*_locked to fget*_noref

This gets rid of the error prone naming where fget_unlocked returns with
a ref held, while fget_locked requires a lock but provides nothing in
terms of making sure the file lives past unlock.

No functional changes.

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fd: make fget_unlocked take a thread argument

Just like other fget routines. This enables embedding fd table pointer
in struct thread, avoiding taking a trip through proc.

selsocket: handle sopoll() errors correctly

Without this change, unmounting smbfs filesystems with an INVARIANTS
kernel would panic after 10e64782ed59727e8c9fe4a5c7e17f497903c8eb.

Found by: markj
R

selsocket: handle sopoll() errors correctly

Without this change, unmounting smbfs filesystems with an INVARIANTS
kernel would panic after 10e64782ed59727e8c9fe4a5c7e17f497903c8eb.

Found by: markj
Reviewed by: markj, jhb
Obtained from: CheriBSD
MFC after: 3 days
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D32492

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Add fspacectl(2), vn_deallocate(9) and VOP_DEALLOCATE(9).

fspacectl(2) is a system call to provide space management support to
userspace applications. VOP_DEALLOCATE(9) is a VOP call to perform the

Add fspacectl(2), vn_deallocate(9) and VOP_DEALLOCATE(9).

fspacectl(2) is a system call to provide space management support to
userspace applications. VOP_DEALLOCATE(9) is a VOP call to perform the
deallocation. vn_deallocate(9) is a public KPI for kmods' use.

The purpose of proposing a new system call, a KPI and a VOP call is to
allow bhyve or other hypervisor monitors to emulate the behavior of SCSI
UNMAP/NVMe DEALLOCATE on a plain file.

fspacectl(2) comprises of cmd and flags parameters to specify the
space management operation to be performed. Currently cmd has to be
SPACECTL_DEALLOC, and flags has to be 0.

fo_fspacectl is added to fileops.
VOP_DEALLOCATE(9) is added as a new VOP call. A trivial implementation
of VOP_DEALLOCATE(9) is provided.

Sponsored by: The FreeBSD Foundation
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D28347

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select: Define select_flags[] as const

MFC after: 1 week
Sponsored by: The FreeBSD Foundation

Split kern_poll() on two counterparts.

The kern_poll_kfds() operates on clear kernel data, kfds points to an
array in the kernel, while kern_poll() operates on user supplied pollfd.
Move nfds check

Split kern_poll() on two counterparts.

The kern_poll_kfds() operates on clear kernel data, kfds points to an
array in the kernel, while kern_poll() operates on user supplied pollfd.
Move nfds check to kern_poll_maxfds().

No functional changes, it's for future use in the Linux emulation layer.

Reviewd by: kib
Differential Revision: https://reviews.freebsd.org/D30690
MFC after: 2 weeks

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poll: use fget_unlocked or fget_only_user when feasible

This follows select by eleminating the use of filedesc lock.
This is a win for single-threaded processes and a mixed bag for others
as at smal

poll: use fget_unlocked or fget_only_user when feasible

This follows select by eleminating the use of filedesc lock.
This is a win for single-threaded processes and a mixed bag for others
as at small concurrency it is faster to take the lock instead of
refing/unrefing each file descriptor.

Nonetheless, removal of shared lock usage is a step towards a
mtx-protected fd table.

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select: employ fget_only_user

Since most select users are single-threaded this avoid a lot of work
in the common case.

For example select of 16 fds (ops/s):
before: 2114536
after: 2991010

Expose eventfd in the native API/ABI using a new __specialfd syscall

eventfd is a Linux system call that produces special file descriptors
for event notification. When porting Linux software, it is

Expose eventfd in the native API/ABI using a new __specialfd syscall

eventfd is a Linux system call that produces special file descriptors
for event notification. When porting Linux software, it is currently
usually emulated by epoll-shim on top of kqueues. Unfortunately, kqueues
are not passable between processes. And, as noted by the author of
epoll-shim, even if they were, the library state would also have to be
passed somehow. This came up when debugging strange HW video decode
failures in Firefox. A native implementation would avoid these problems
and help with porting Linux software.

Since we now already have an eventfd implementation in the kernel (for
the Linuxulator), it's pretty easy to expose it natively, which is what
this patch does.

Submitted by: greg@unrelenting.technology
Reviewed by: markj (previous version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D26668

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select: make sure there are no wakeup attempts after selfdfree returns

Prior to the patch returning selfdfree could still be racing against doselwakeup
which set sf_si = NULL and now locks stp to wa

select: make sure there are no wakeup attempts after selfdfree returns

Prior to the patch returning selfdfree could still be racing against doselwakeup
which set sf_si = NULL and now locks stp to wake up the other thread.

A sufficiently unlucky pair can end up going all the way down to freeing
select-related structures before the lock/wakeup/unlock finishes.

This started manifesting itself as crashes since select data started getting
freed in r367714.

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select: replace reference counting with memory barriers in selfd

Refcounting was added to combat a race between selfdfree and doselwakup,
but it adds avoidable overhead.

selfdfree detects it can fr

select: replace reference counting with memory barriers in selfd

Refcounting was added to combat a race between selfdfree and doselwakup,
but it adds avoidable overhead.

selfdfree detects it can free the object by ->sf_si == NULL, thus we can
ensure that the condition only holds after all accesses are completed.

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poll/select: change selfd_zone into a malloc type

On a sample box vmstat -z shows:

ITEM SIZE LIMIT USED FREE REQ
64: 64, 0, 1043784, 436753

poll/select: change selfd_zone into a malloc type

On a sample box vmstat -z shows:

ITEM SIZE LIMIT USED FREE REQ
64: 64, 0, 1043784, 4367538,3698187229
selfd: 64, 0, 1520, 13726,182729008

But at the same time:
vm.uma.selfd.keg.domain.1.pages: 121
vm.uma.selfd.keg.domain.0.pages: 121

Thus 242 pages got pulled even though the malloc zone would likely accomodate
the load without using extra memory.

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