Since this is called in fork() it does rather need to give the child
process the parent's emulation root.
This means that (for example) an emulated shell will, by default, run
programs from the emulation root.
avoid having to allocate space in the 'stackgap'
- which is very LWP unfriendly.
The additional code for non-emulation namei() is trivial, the reduction for
the emulations is massive.
The vnode for a processes emulation root is saved in the cwdi structure
during process exec.
If the emulation root the TRYEMULROOT flag are set, namei() will do an initial
search for absolute pathnames in the emulation root, if that fails it will
retry from the normal root.
".." at the emulation root will always go to the real root, even in the middle
of paths and when expanding symlinks.
Absolute symlinks found using absolute paths in the emulation root will be
relative to the emulation root (so /usr/lib/xxx.so -> /lib/xxx.so links
inside the emulation root don't need changing).
If the root of the emulation would be returned (for an emulation lookup), then
the real root is returned instead (matching the behaviour of emul_lookup,
but being a cheap comparison here) so that programs that scan "../.."
looking for the root dircetory don't loop forever.
The target for symbolic links is no longer mangled (it used to get the
CHECK_ALT_xxx() treatment, so could get /emul/xxx prepended).
CHECK_ALT_xxx() are no more. Most of the change is deleting them, and adding
TRYEMULROOT to the flags to NDINIT().
A lot of the emulation system call stubs could now be deleted.
to skip unnecessary flushing when layered file system vnodes are recycled.
this also prevents a deadlock with the dodgy LFS putpages routine.
fixes the non-LFS part of PR 36150.
the "mountpoint" vnode twice due to an error branch.
thanks go to Gert Doering for reporting the problem and testing the fix
and to Juergen Hannken-Illjes for much of the analysis work leading to
the discovery of the problem cause
corresponding flags.
Revert softdep_trackbufs() to its state before vn_start_write() was added.
Remove from struct mount now unneeded flags IMNT_SUSPEND* and
members mnt_writeopcountupper, mnt_writeopcountlower and mnt_leaf.
Welcome to 4.99.17
Make sure that if we pull a buffer off of the read queue that it really
is a read request. Lower in this routine we base which queue we
dequeue the request from on its read/write state. Thus if a write
op ever ended up on the read queue, we'd explode (dereference NULL).
- cv_wait and friends: after resuming execution, check to see if we have
been restarted as a result of cv_signal. If we have, but cannot take
the wakeup (because of eg a pending Unix signal or timeout) then try to
ensure that another LWP sees it. This is necessary because there may
be multiple waiters, and at least one should take the wakeup if possible.
Prompted by a discussion with pooka@.
- typedef struct lwp lwp_t;
- int -> bool, struct lwp -> lwp_t in a few places.
- Better detect simple cycles of threads calling _lwp_wait and return
EDEADLK. Does not handle deeper cycles like t1 -> t2 -> t3 -> t1.
- If there are multiple threads in _lwp_wait, then make sure that
targeted waits take precedence over waits for any LWP to exit.
- When checking for deadlock, also count the number of zombies currently
in the process as potentially reapable. Whenever a zombie is murdered,
kick all waiters to make them check again for deadlock.
- Add more comments.
Also, while here:
- LOCK_ASSERT -> KASSERT in some places
- lwp_free: change boolean arguments to type 'bool'.
- proc_free: let lwp_free spin waiting for the last LWP to exit, there's
no reason to do it here.
- Don't bother sorting the sleep queues, since user space controls the
order of removal.
- Change setrunnable(t) to lwp_unsleep(t). No functional change from the
perspective of user applications.
- Minor cosmetic changes.
so it's not worth counting.
- lwp_wakeup: set LW_UNPARKED on the target. Ensures that _lwp_park will
always be awoken even if another system call eats the wakeup, e.g. as a
result of an intervening signal. To deal with this correctly for other
system calls will require a different approach.
- _lwp_unpark, _lwp_unpark_all: use setrunnable if the LWP is not parked
on the same sync queue: (1) simplifies the code a bit as there no point
doing anything special for this case (2) makes it possible for p_smutex
to be replaced by p_mutex and (3) restores the guarantee that the 'hint'
argument really is just a hint.
dsl