remove unneeded includes in sys/kern
ok mpi@ miod@

Stop hiding a few assertions behind the opt-in LOCKF_DIAGNOSTIC option.
This code has already been exercised quite extensively by syzkaller and
got decent test coverage.

Fix ambiguity with lock range end

When the user requests a lock range that ends at LLONG_MAX, replace
the end point with the special EOF value -1. This avoids ambiguity
with lf_end in lf_split(). Th

Fix ambiguity with lock range end

When the user requests a lock range that ends at LLONG_MAX, replace
the end point with the special EOF value -1. This avoids ambiguity
with lf_end in lf_split(). The ambiguity could result in a broken
data structure.

This change is visible to userspace in a corner case. When a lock range
has been requested with an end point at absolute position LLONG_MAX,
fcntl(F_GETLK) returns l_len == 0, instead of a positive value, for that
range. This seems consistent with FreeBSD and Linux.

OK anton@

Reported-by: syzbot+c93afea6c27a3fa3af39@syzkaller.appspotmail.com

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Fix lock range start when l_whence == SEEK_END and l_len < 0.

OK anton@

Remove the lock if an identical overlapping one is already present.
Preventing a use after free discovered by syzkaller.

ok visa@

Reported-by: syzbot+a2649c1d77e9d2463f33@syzkaller.appspotmail.com

Remove the lock if an identical overlapping one is already present.
Preventing a use after free discovered by syzkaller.

ok visa@

Reported-by: syzbot+a2649c1d77e9d2463f33@syzkaller.appspotmail.com
Reported-by: syzbot+182df9087f5f182daa44@syzkaller.appspotmail.com
Reported-by: syzbot+46d03139d7ed5e81ed2f@syzkaller.appspotmail.com
Reported-by: syzbot+892e886a6113db341da1@syzkaller.appspotmail.com

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Replace rwsleep(9) with rwsleep_nsec(9) in vfs_lockf.c.

Prompted by and OK cheloha@
OK mpi@ anton@

Remove now unneeded kernel locking from vfs_lockf.c.

OK mpi@ anton@

no need to store the wmesg passed to rwsleep() as a static variable anymore

Restore previous behavior of limiting deadlock detection to posix-style
locks.

ok jturner@ visa@

Reported-by: syzbot+f9f13034fd656af6c48f@syzkaller.appspotmail.com

group function prototypes

Bring back lockf deadlock detection from the dead. Back in 2007, the deadlock
detection broke while changing the owner of a lock from struct proc to struct
filedesc/file. Instead of keeping track of

Bring back lockf deadlock detection from the dead. Back in 2007, the deadlock
detection broke while changing the owner of a lock from struct proc to struct
filedesc/file. Instead of keeping track of the owning proc for each lock,
introduce a new list for all pending blocked locks. This list is scanned before
waiting on a blocking lock in order to determine if sleeping would cause a
deadlock.

The new implementation is serialized by the recently added locking to the same
subsystem, meaning that acquiring the kernel lock is no longer necessary.

ok visa@

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print locked range in decimal in debug routines

Move lockf structures from header to implementation since external users
only need a lockf_state pointer by now.

ok mpi@ visa@

Add a subsystem lock for vfs_lockf.c. This enables calling lf_advlock()
and lf_purgelocks() without the kernel lock.

OK anton@ mpi@

Move the prototypes of internal lockf functions from <sys/lockf.h>
to vfs_lockf.c. This makes the public interface clearer.

The declaration of variable lockf_debug is removed from the header
because

Move the prototypes of internal lockf functions from <sys/lockf.h>
to vfs_lockf.c. This makes the public interface clearer.

The declaration of variable lockf_debug is removed from the header
because it is not needed outside of vfs_lockf.c.

OK anton@ tedu@

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always include the lock id address in debug output

initialize struct lockf fields in a consistent order; ok millert@ mpi@ visa@

Replace hand rolled linked list with TAILQ. All made possible by the recent
introduction of struct lockf_state.

ok bluhm@ visa@

Introduce a dedicated entry point data structure for file locks. This new data
structure allows for better tracking of pending lock operations which is
essential in order to prevent a use-after-free

Introduce a dedicated entry point data structure for file locks. This new data
structure allows for better tracking of pending lock operations which is
essential in order to prevent a use-after-free once the underlying vnode is
gone.

Inspired by the lockf implementation in FreeBSD.

ok visa@

Reported-by: syzbot+d5540a236382f50f1dac@syzkaller.appspotmail.com

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use the LFPRINTF() debug macro consistently; ok mpi@

Conform to POSIX-2001 in which the behavior of passing a negative length using
posix file locks is defined. Also, detect overflows when dealing with positive
lengths.

ok millert@ visa@

make debug flags continuous

Add assertions for lockf list manipulation, hidden behind LOCKF_DIAGNOSTIC.
While here, improve existing lockf debug routines and sprinkle some more logging
related to list manipulation.

ok deraadt@

Add assertions for lockf list manipulation, hidden behind LOCKF_DIAGNOSTIC.
While here, improve existing lockf debug routines and sprinkle some more logging
related to list manipulation.

ok deraadt@ visa@ (as part of a larger diff)

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Rework previous lockf fix; bluhm@ noticed a regress failure during consecutive
runs. This is a second attempt in which the lockf structure is turned into a
doubly linked list which makes it easier to

Rework previous lockf fix; bluhm@ noticed a regress failure during consecutive
runs. This is a second attempt in which the lockf structure is turned into a
doubly linked list which makes it easier to ensure correctness during list
insertion and deletion.

ok deraadt@ visa@

show more ...

When freeing a lockf struct that already is part of a linked list, make sure to
update the next pointer for the preceding lock. Prevents a double free panic.

ok millert@