Group mutexes used in hwpmc(4) into 3 "types" in the sense of
witness(4):
- leaf spin mutexes---only one of these should be held at a time,
so these mutexes are specified as belonging to a single witness
type "pmc-leaf".
- `struct pmc_owner' descriptors are protected by a spin mutex of
witness type "pmc-owner-proc". Since we call wakeup_one() while
holding these mutexes, the witness type of these mutexes needs
to dominate that of "sleepq chain" mutexes.
- logger threads use a sleep mutex, of type "pmc-sleep".
Submitted by: wkoszek (earlier patch)
When nbytes=0, sendfile(2) should use file size. Because of the bug, it
was sending half of a file. The bug is that 'off' variable can't be used
for size calculation, because it changes inside the loop, so we should
use uap->offset instead.
gets a bogus irq storm detected when periodic daily kicks off at 3 am
and disconnects the disk. Change the print logic to print once per second
when the storm is occurring instead of only once. Otherwise, it appeared
that something else was causing the errors each night at 3 am since the
print only occurred the first time.
Reviewed by: jhb
MFC after: 1 week
- We need to allow for PRIV_VFS_MOUNT_OWNER inside a jail.
- Move security checks to vfs_suser() and deny unmounting and updating
for jailed root from different jails, etc.
OK'ed by: rwatson
I converted allprison_mtx mutex to allprison_lock sx lock. To fix this LOR,
move prison removal to prison_complete() entirely. To ensure that noone
will reference this prison before it's beeing removed from the list skip
prisons with 'pr_ref == 0' in prison_find() and assert that pr_ref has to
greater than 0 in prison_hold().
Reported by: kris
OK'ed by: rwatson
It may be used for external modules to attach some data to jail's in-kernel
structure.
- Change allprison_mtx mutex to allprison_sx sx(9) lock.
We will need to call external functions while holding this lock, which may
want to allocate memory.
Make use of the fact that this is shared-exclusive lock and use shared
version when possible.
- Implement the following functions:
prison_service_register() - registers a service that wants to be noticed
when a jail is created and destroyed
prison_service_deregister() - deregisters service
prison_service_data_add() - adds service-specific data to the jail structure
prison_service_data_get() - takes service-specific data from the jail
structure
prison_service_data_del() - removes service-specific data from the jail
structure
Reviewed by: rwatson
unmount jail-friendly file systems from within a jail.
Precisely it grants PRIV_VFS_MOUNT, PRIV_VFS_UNMOUNT and
PRIV_VFS_MOUNT_NONUSER privileges for a jailed super-user.
It is turned off by default.
A jail-friendly file system is a file system which driver registers
itself with VFCF_JAIL flag via VFS_SET(9) API.
The lsvfs(1) command can be used to see which file systems are
jail-friendly ones.
There currently no jail-friendly file systems, ZFS will be the first one.
In the future we may consider marking file systems like nullfs as
jail-friendly.
Reviewed by: rwatson
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared locking for
frequent lookup operations, reduced general overhead, and reduced overhead
in the event of contention. All of these are imported for threaded
applications where simultaneous access to a shared file descriptor array
occurs frequently. Kris has reported 2x-4x transaction rate improvements
on 8-core MySQL benchmarks; smaller improvements can be expected for many
workloads as a result of reduced overhead.
- Generally eliminate the distinction between "fast" and regular
acquisisition of the filedesc lock; the plan is that they will now all
be fast. Change all locking instances to either shared or exclusive
locks.
- Correct a bug (pointed out by kib) in fdfree() where previously msleep()
was called without the mutex held; sx_sleep() is now always called with
the sxlock held exclusively.
- Universally hold the struct file lock over changes to struct file,
rather than the filedesc lock or no lock. Always update the f_ops
field last. A further memory barrier is required here in the future
(discussed with jhb).
- Improve locking and reference management in linux_at(), which fails to
properly acquire vnode references before using vnode pointers. Annotate
improper use of vn_fullpath(), which will be replaced at a future date.
In fcntl(), we conservatively acquire an exclusive lock, even though in
some cases a shared lock may be sufficient, which should be revisited.
The dropping of the filedesc lock in fdgrowtable() is no longer required
as the sxlock can be held over the sleep operation; we should consider
removing that (pointed out by attilio).
Tested by: kris
Discussed with: jhb, kris, attilio, jeff
- Close the new file objects created during socketpair() if the copyout of
the new file descriptors fails.
- Add a test to the socketpair regression test for this edge case.
file descriptor is closed out from under us in kern_open(). This race
is already handled and the file will be closed when kern_open() does an
fdrop just before returning.
vfs_flags field is used for VFCF_* flags which are given at file system
driver creation time (via VFS_SET(9)) macro.
What this code did was bascially this:
If file system registers itself with VFCF_UNICODE flag (stores file names
as Unicode), it will gain MNT_SOFTDEP flag (UFS soft-updates).
If file system registers itself with VFCF_LOOPBACK flag (aliases some other
mounted FS), it will gain MNT_SUIDDIR flag (special handling of SUID on
dirs).
The latter will be quite dangerous, but those flags are reset later in
vfs_domount().
MFC after: 1 month
file system code (mostly *_reclaim()) which look like this:
VOP_LOCK(vp);
/* examine vp */
VOP_UNLOCK(vp);
vdrop(vp);
This can now be rewritten to:
VOP_LOCK(vp);
/* examine vp */
vdropl(vp); /* will unlock vp */
MFC after: 1 week
obtaining and releasing shared and exclusive locks. The algorithms for
manipulating the lock cookie are very similar to that rwlocks. This patch
also adds support for exclusive locks using the same algorithm as mutexes.
A new sx_init_flags() function has been added so that optional flags can be
specified to alter a given locks behavior. The flags include SX_DUPOK,
SX_NOWITNESS, SX_NOPROFILE, and SX_QUITE which are all identical in nature
to the similar flags for mutexes.
Adaptive spinning on select locks may be enabled by enabling the
ADAPTIVE_SX kernel option. Only locks initialized with the SX_ADAPTIVESPIN
flag via sx_init_flags() will adaptively spin.
The common cases for sx_slock(), sx_sunlock(), sx_xlock(), and sx_xunlock()
are now performed inline in non-debug kernels. As a result, <sys/sx.h> now
requires <sys/lock.h> to be included prior to <sys/sx.h>.
The new kernel option SX_NOINLINE can be used to disable the aforementioned
inlining in non-debug kernels.
The size of struct sx has changed, so the kernel ABI is probably greatly
disturbed.
MFC after: 1 month
Submitted by: attilio
Tested by: kris, pjd
explicitly test and panic. This should not ever happen, but if it does,
this is a preferred failure mode to a NULL pointer dereference in kernel.
Coverity CID: 1716
Found with: Coverity Prevent(tm)
We can now use LOCK_CLASS() as a stronger check in lockmgr_chain() as a
result. This required putting back lk_flags as lockmgr's use of flags
conflicted with other flags in lo_flags otherwise.
- Tweak 'show lock' output for lockmgr to match sx, rw, and mtx.
always 0. Previously we aligned threads on a minimum of 8-byte boundaries.
Note: This changes the uma zone to no longer cache align threads. We
really want the uma zone to do align threads to MAX(16, cache line size)
but there currently isn't a good way to express that to uma.
Submitted by: attilio
