filedesc: simplify fget_unlocked & friends

Introduce fget_fcntl which performs appropriate checks when needed.
This removes a branch from fget_unlocked.

Introduce fget_mmap dealing with cap_rights_

filedesc: simplify fget_unlocked & friends

Introduce fget_fcntl which performs appropriate checks when needed.
This removes a branch from fget_unlocked.

Introduce fget_mmap dealing with cap_rights_to_vmprot conversion.
This removes a branch from _fget.

Modify fget_unlocked to pass sequence counter to interested callers so
that they can perform their own checks and make sure the result was
otained from stable & current state.

Reviewed by: silence on -hackers

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Merge from head@274682

Reintegrate head@r273095

Sponsored by: The FreeBSD Foundation

Merge HEAD@r272944.

IFC @r272887

Sync to HEAD@r272825.

Fix draining in ttydev_leave():
1. ERESTART is not only returned when the revoke count changed. It
is also returned when a signal is received. While a change in
the revoke count should be ig

Fix draining in ttydev_leave():
1. ERESTART is not only returned when the revoke count changed. It
is also returned when a signal is received. While a change in
the revoke count should be ignored, a signal should not.
2. Waiting until the output queue is entirely drained can cause a
hang when the underlying device is stuck or broken.

Have tty_drain() take care of this by telling it when we're leaving.
When leaving, tty_drain() will use a timed wait to address point 2
above and it will check the revoke count to handle point 1 above.
The timeout is set to 1 second, which is arbitrary and long enough
to expect a change in the output queue.

Discussed with: jilles@
Reported by: Yamagi Burmeister <lists@yamagi.org>

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Apply r269126 to tty_timedwait():
Don't return ERESTART when the device is gone.

IFC @r272481

Sync to HEAD@r272516.

Reintegrate head@r272414

Sponsored by: The FreeBSD Foundation

tty_rel_free() can be called more than once for the same tty so make sure
that the tty is dequeued from 'tty_list' only the first time.

The panic below was seen when a revoke(2) was issued on an nmd

tty_rel_free() can be called more than once for the same tty so make sure
that the tty is dequeued from 'tty_list' only the first time.

The panic below was seen when a revoke(2) was issued on an nmdm device.
In this case there was also a thread that was blocked on a read(2) on the
device. The revoke(2) woke up the blocked thread which would typically
return an error to userspace. In this case the reader also held the last
reference on the file descriptor so fdrop() ended up calling tty_rel_free()
via ttydev_close().

tty_rel_free() then tried to dequeue 'tp' again which led to the panic.

panic: Bad link elm 0xfffff80042602400 prev->next != elm
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00f9c90460
kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe00f9c90510
vpanic() at vpanic+0x189/frame 0xfffffe00f9c90590
panic() at panic+0x43/frame 0xfffffe00f9c905f0
tty_rel_free() at tty_rel_free+0x29b/frame 0xfffffe00f9c90640
ttydev_close() at ttydev_close+0x1f9/frame 0xfffffe00f9c90690
devfs_close() at devfs_close+0x298/frame 0xfffffe00f9c90720
VOP_CLOSE_APV() at VOP_CLOSE_APV+0x13c/frame 0xfffffe00f9c90770
vn_close() at vn_close+0x194/frame 0xfffffe00f9c90810
vn_closefile() at vn_closefile+0x48/frame 0xfffffe00f9c90890
devfs_close_f() at devfs_close_f+0x2c/frame 0xfffffe00f9c908c0
_fdrop() at _fdrop+0x29/frame 0xfffffe00f9c908e0
sys_read() at sys_read+0x63/frame 0xfffffe00f9c90980
amd64_syscall() at amd64_syscall+0x2b3/frame 0xfffffe00f9c90ab0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe00f9c90ab0
--- syscall (3, FreeBSD ELF64, sys_read), rip = 0x800b78d8a, rsp = 0x7fffffbfdaf8, rbp = 0x7fffffbfdb30 ---

CR: https://reviews.freebsd.org/D851
Reviewed by: glebius, ed
Reported by: Leon Dang
Sponsored by: Nahanni Systems
MFC after: 1 week

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IFC @r269962

Submitted by: Anish Gupta (akgupt3@gmail.com)

Merge head from 7/28

Sync to HEAD@r269943.

Don't return ERESTART when the device is gone. In ttydev_leave() ERESTART
is the indication that draining got interrupted due to a revoke(2) and
that tty_drain() is to be called again for draining to

Don't return ERESTART when the device is gone. In ttydev_leave() ERESTART
is the indication that draining got interrupted due to a revoke(2) and
that tty_drain() is to be called again for draining to complete. If the
device is flagged as gone, then waiting/draining is not possible. Only
return ERESTART when waiting is still possible.

Obtained from: Juniper Networks, Inc.

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MFC @ r266724

An SVM update will follow this.

Merge head

IFC @264767

Merge head up to r263906.

Update kernel inclusions of capability.h to use capsicum.h instead; some
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version

Update kernel inclusions of capability.h to use capsicum.h instead; some
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.

MFC after: 3 weeks

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MFC @ r259635

This brings in the "-w" option from bhyve to ignore unknown MSRs.
It will make debugging Linux guests a bit easier.

Suggested by: Willem Jan Withagen (wjw at digiware nl)

Merge head up to r262222 (last merge was incomplete).

Move list of ttys handling from the allocating procedures, to the
device creation stage. A device creation can fail, and in that case
an entry already on the list will be freed.

Sponsored by: Nginx,

Move list of ttys handling from the allocating procedures, to the
device creation stage. A device creation can fail, and in that case
an entry already on the list will be freed.

Sponsored by: Nginx, Inc.

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- Rename tty_makedev() into tty_makedevf() and make it capable
to fail and return error.
- Use make_dev_p() in tty_makedevf() instead of make_dev_cred().
- Always pass MAKEDEV_CHECKNAME flag.
- Opt

- Rename tty_makedev() into tty_makedevf() and make it capable
to fail and return error.
- Use make_dev_p() in tty_makedevf() instead of make_dev_cred().
- Always pass MAKEDEV_CHECKNAME flag.
- Optionally pass MAKEDEV_REF flag.
- Provide macro for compatibility with old API.

This fixes races with simultaneous creation and desctruction of
ttys, and makes it possible to call tty_makedevf() from device
cloners.

A race in tty_watermarks() still exist, since the latter drops
lock for M_WAITOK allocation. This will be addressed in separate
commit.

Reviewed by: kib
Sponsored by: Nginx, Inc.

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