- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-process
scheduling synchronization.
Tested by: kris, current@
Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
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
- Remove also "MP SAFE" after prior "MPSAFE" pass. (suggested by bde)
- Remove extra blank lines in some cases.
- Add extra blank lines in some cases.
- Remove no-op comments consisting solely of the function name, the word
"syscall", or the system call name.
- Add punctuation.
- Re-wrap some comments.
system calls now enter without Giant held, and then in some cases, acquire
Giant explicitly.
Remove a number of other MPSAFE annotations in the credential code and
tweak one or two other adjacent comments.
this patch the code behaves according to the comment on the line above.
Without this patch, a socket could cause SIGPIPE to be delivered to its
process, once with SO_NOSIGPIPE set, and twice without.
With this patch, the kernel now passes the sigpipe regression test.
Tested by: Anton Yuzhaninov
MFC after: 1 week
if backward copatibility options are present) from attempting
to free memory that wasn't allocated. This is an old bug, and
previously it would attempt to free a null pointer. I noticed
this bug when working on the previous revision, but forgot to
fix it.
Security: local DoS
Reported by: Peter Holm
MFC after: 3 days
ioctls passing integer arguments should use the _IOWINT() macro.
This fixes a lot of ioctl's not working on sparc64, most notable
being keyboard/syscons ioctls.
Full ABI compatibility is provided, with the bonus of fixing the
handling of old ioctls on sparc64.
Reviewed by: bde (with contributions)
Tested by: emax, marius
MFC after: 1 week
that the 'data' pointer is already setup to point to a valid KVM buffer
or contains the copied-in data from userland as appropriate (ioctl(2)
still does this). kern_ioctl() takes care of looking up a file pointer,
implementing FIONCLEX and FIOCLEX, and calling fi_ioctl().
- Use kern_ioctl() to implement xenix_rdchk() instead of using the stackgap
and mark xenix_rdchk() MPSAFE.
returns EBADF. That errno is correct and is mandated by POSIX. It also
goes back to revision 1.1 of our CVS history (i.e. 4.4BSD).
The _fget() function should probably also be upated as it currently returns
EINVAL in that case rather than EBADF. (It does return EBADF for reads
on a write-only descriptor without any XXX comments oddly enough.)
Discussed with: scottl, grog, mjacob, bde
and writev() except that they take an additional offset argument and do
not change the current file position. In SAT speak:
preadv:readv::pread:read and pwritev:writev::pwrite:write.
- Try to reduce code duplication some by merging most of the old
kern_foov() and dofilefoo() functions into new dofilefoo() functions
that are called by kern_foov() and kern_pfoov(). The non-v functions
now all generate a simple uio on the stack from the passed in arguments
and then call kern_foov(). For example, read() now just builds a uio and
calls kern_readv() and pwrite() just builds a uio and calls kern_pwritev().
PR: kern/80362
Submitted by: Marc Olzheim marcolz at stack dot nl (1)
Approved by: re (scottl)
MFC after: 1 week
ioctl numbers in backwards compatability mode. eg: an IOC_IN ioctl with
a size of zero. Traditionally this was what you did before IOC_VOID
existed, and we had some established users of this in the tree, namely
procfs. Certain 3rd party drivers with binary userland components also
have this too.
This is necessary to have 4.x and 5.x binaries use these ioctl's. We
found this at work when trying to run 4.x binaries.
Approved by: re
missed that when the vnode bypass was introduced.
Deal with zero length transfers before we even get to fo_ops->fo_read().
Found by: Slawa Olhovchenkov <slwzxy.spb.ru@zxy.spb.ru>
PR: 75758
Don't grab Giant in the upper syscall/wrapper code
NET_LOCK_GIANT in the socket code (sockets/fifos).
mtx_lock(&Giant) in the vnode code.
mtx_lock(&Giant) in the opencrypto code. (This may actually not be
needed, but better safe than sorry).
Devfs grabs Giant if the driver is marked as needing Giant.
Don't grab Giant in the upper syscall/wrapper code
NET_LOCK_GIANT in the socket code (sockets/fifos).
mtx_lock(&Giant) in the vnode code.
Devfs grabs Giant if the driver is marked as needing Giant.
Use this in all the places where sleeping with the lock held is not
an issue.
The distinction will become significant once we finalize the exact
lock-type to use for this kind of case.
pollfd's to avoid calling malloc() on small numbers of fd's. Because
smalltype's members have type char, its address might be misaligned
for a struct pollfd. Change the array of char to an array of struct
pollfd.
PR: kern/58214
Submitted by: Stefan Farfeleder <stefan@fafoe.narf.at>
Reviewed by: bde (a long time ago)
MFC after: 3 days
Add copyiniov() which copies a struct iovec array in from userland into
a malloc'ed struct iovec. Caller frees.
Change uiofromiov() to malloc the uio (caller frees) and name it
copyinuio() which is more appropriate.
Add cloneuio() which returns a malloc'ed copy. Caller frees.
Use them throughout.
we always grab Giant, even if we're actually only polling objects that
don't require giant. Once socket locking is merged, there will be
strong motivation to fix this.
sleep queue interface:
- Sleep queues attempt to merge some of the benefits of both sleep queues
and condition variables. Having sleep qeueus in a hash table avoids
having to allocate a queue head for each wait channel. Thus, struct cv
has shrunk down to just a single char * pointer now. However, the
hash table does not hold threads directly, but queue heads. This means
that once you have located a queue in the hash bucket, you no longer have
to walk the rest of the hash chain looking for threads. Instead, you have
a list of all the threads sleeping on that wait channel.
- Outside of the sleepq code and the sleep/cv code the kernel no longer
differentiates between cv's and sleep/wakeup. For example, calls to
abortsleep() and cv_abort() are replaced with a call to sleepq_abort().
Thus, the TDF_CVWAITQ flag is removed. Also, calls to unsleep() and
cv_waitq_remove() have been replaced with calls to sleepq_remove().
- The sched_sleep() function no longer accepts a priority argument as
sleep's no longer inherently bump the priority. Instead, this is soley
a propery of msleep() which explicitly calls sched_prio() before
blocking.
- The TDF_ONSLEEPQ flag has been dropped as it was never used. The
associated TDF_SET_ONSLEEPQ and TDF_CLR_ON_SLEEPQ macros have also been
dropped and replaced with a single explicit clearing of td_wchan.
TD_SET_ONSLEEPQ() would really have only made sense if it had taken
the wait channel and message as arguments anyway. Now that that only
happens in one place, a macro would be overkill.
- struct plimit includes a mutex to protect a reference count. The plimit
structure is treated similarly to struct ucred in that is is always copy
on write, so having a reference to a structure is sufficient to read from
it without needing a further lock.
- The proc lock protects the p_limit pointer and must be held while reading
limits from a process to keep the limit structure from changing out from
under you while reading from it.
- Various global limits that are ints are not protected by a lock since
int writes are atomic on all the archs we support and thus a lock
wouldn't buy us anything.
- All accesses to individual resource limits from a process are abstracted
behind a simple lim_rlimit(), lim_max(), and lim_cur() API that return
either an rlimit, or the current or max individual limit of the specified
resource from a process.
- dosetrlimit() was renamed to kern_setrlimit() to match existing style of
other similar syscall helper functions.
- The alpha OSF/1 compat layer no longer calls getrlimit() and setrlimit()
(it didn't used the stackgap when it should have) but uses lim_rlimit()
and kern_setrlimit() instead.
- The svr4 compat no longer uses the stackgap for resource limits calls,
but uses lim_rlimit() and kern_setrlimit() instead.
- The ibcs2 compat no longer uses the stackgap for resource limits. It
also no longer uses the stackgap for accessing sysctl's for the
ibcs2_sysconf() syscall but uses kernel_sysctl() instead. As a result,
ibcs2_sysconf() no longer needs Giant.
- The p_rlimit macro no longer exists.
Submitted by: mtm (mostly, I only did a few cleanups and catchups)
Tested on: i386
Compiled on: alpha, amd64
thread being waken up. The thread waken up can run at a priority as
high as after tsleep().
- Replace selwakeup()s with selwakeuppri()s and pass appropriate
priorities.
- Add cv_broadcastpri() which raises the priority of the broadcast
threads. Used by selwakeuppri() if collision occurs.
Not objected in: -arch, -current
do exactly the same as vop_nopoll() for consistency and put a
comment in the two pointing at each other.
Retire seltrue() in favour of no_poll().
Create private default functions in kern_conf.c instead of public
ones.
Change default strategy to return the bio with ENODEV instead of
doing nothing which would lead the bio stranded.
Retire public nullopen() and nullclose() as well as the entire band
of public no{read,write,ioctl,mmap,kqfilter,strategy,poll,dump}
funtions, they are the default actions now.
Move the final two trivial functions from subr_xxx.c to kern_conf.c
and retire the now empty subr_xxx.c
a kernel-internal kern_*() version and a wrapper that is called via
the syscall vector table. For paths and structure pointers, the
internal version either takes a uio_seg parameter or requires the
caller to copyin() the data to kernel memory as appropiate. This
will permit emulation layers to use these syscalls without having
to copy out translated arguments to the stack gap.
Discussed on: -arch
Review/suggestions: bde, jhb, peter, marcel
some circumstances when we get a select collision, we can end up with
cases where we do not clear some sip->si_thread on the way out, leading to
page faults in selwakeup(). This should solve the problem where postfix
can crash the kernel during select collisions.
Reviewed by: alfred
accept an 'active_cred' argument reflecting the credential of the thread
initiating the ioctl operation.
- Change fo_ioctl() to accept active_cred; change consumers of the
fo_ioctl() interface to generally pass active_cred from td->td_ucred.
- In fifofs, initialize filetmp.f_cred to ap->a_cred so that the
invocations of soo_ioctl() are provided access to the calling f_cred.
Pass ap->a_td->td_ucred as the active_cred, but note that this is
required because we don't yet distinguish file_cred and active_cred
in invoking VOP's.
- Update kqueue_ioctl() for its new argument.
- Update pipe_ioctl() for its new argument, pass active_cred rather
than td_ucred to MAC for authorization.
- Update soo_ioctl() for its new argument.
- Update vn_ioctl() for its new argument, use active_cred rather than
td->td_ucred to authorize VOP_IOCTL() and the associated VOP_GETATTR().
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
fo_read() and fo_write(): explicitly use the cred argument to fo_poll()
as "active_cred" using the passed file descriptor's f_cred reference
to provide access to the file credential. Add an active_cred
argument to fo_stat() so that implementers have access to the active
credential as well as the file credential. Generally modify callers
of fo_stat() to pass in td->td_ucred rather than fp->f_cred, which
was redundantly provided via the fp argument. This set of modifications
also permits threads to perform these operations on behalf of another
thread without modifying their credential.
Trickle this change down into fo_stat/poll() implementations:
- badfo_poll(), badfo_stat(): modify/add arguments.
- kqueue_poll(), kqueue_stat(): modify arguments.
- pipe_poll(), pipe_stat(): modify/add arguments, pass active_cred to
MAC checks rather than td->td_ucred.
- soo_poll(), soo_stat(): modify/add arguments, pass fp->f_cred rather
than cred to pru_sopoll() to maintain current semantics.
- sopoll(): moidfy arguments.
- vn_poll(), vn_statfile(): modify/add arguments, pass new arguments
to vn_stat(). Pass active_cred to MAC and fp->f_cred to VOP_POLL()
to maintian current semantics.
- vn_close(): rename cred to file_cred to reflect reality while I'm here.
- vn_stat(): Add active_cred and file_cred arguments to vn_stat()
and consumers so that this distinction is maintained at the VFS
as well as 'struct file' layer. Pass active_cred instead of
td->td_ucred to MAC and to VOP_GETATTR() to maintain current semantics.
- fifofs: modify the creation of a "filetemp" so that the file
credential is properly initialized and can be used in the socket
code if desired. Pass ap->a_td->td_ucred as the active
credential to soo_poll(). If we teach the vnop interface about
the distinction between file and active credentials, we would use
the active credential here.
Note that current inconsistent passing of active_cred vs. file_cred to
VOP's is maintained. It's not clear why GETATTR would be authorized
using active_cred while POLL would be authorized using file_cred at
the file system level.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
make a series of modifications to the credential arguments relating
to file read and write operations to cliarfy which credential is
used for what:
- Change fo_read() and fo_write() to accept "active_cred" instead of
"cred", and change the semantics of consumers of fo_read() and
fo_write() to pass the active credential of the thread requesting
an operation rather than the cached file cred. The cached file
cred is still available in fo_read() and fo_write() consumers
via fp->f_cred. These changes largely in sys_generic.c.
For each implementation of fo_read() and fo_write(), update cred
usage to reflect this change and maintain current semantics:
- badfo_readwrite() unchanged
- kqueue_read/write() unchanged
pipe_read/write() now authorize MAC using active_cred rather
than td->td_ucred
- soo_read/write() unchanged
- vn_read/write() now authorize MAC using active_cred but
VOP_READ/WRITE() with fp->f_cred
Modify vn_rdwr() to accept two credential arguments instead of a
single credential: active_cred and file_cred. Use active_cred
for MAC authorization, and select a credential for use in
VOP_READ/WRITE() based on whether file_cred is NULL or not. If
file_cred is provided, authorize the VOP using that cred,
otherwise the active credential, matching current semantics.
Modify current vn_rdwr() consumers to pass a file_cred if used
in the context of a struct file, and to always pass active_cred.
When vn_rdwr() is used without a file_cred, pass NOCRED.
These changes should maintain current semantics for read/write,
but avoid a redundant passing of fp->f_cred, as well as making
it more clear what the origin of each credential is in file
descriptor read/write operations.
Follow-up commits will make similar changes to other file descriptor
operations, and modify the MAC framework to pass both credentials
to MAC policy modules so they can implement either semantic for
revocation.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
