the syscall code and acquires various event subsystem locks as needed.
The handling of the NOTE_TRACK for EVFILT_PROC is currently done by
calling the kqueue_register() from filt_proc() filter, causing recursive
entrance of the kqueue code. This results in the LORs and recursive
acquisition of the locks.
Implement the variant of the knote() function designed to only handle
the fork() event. It mostly copies the knote() body, but also handles
the NOTE_TRACK, removing the handling from the filt_proc(), where it
causes problems described above. The function is called from the fork1()
instead of knote().
When encountering NOTE_TRACK knote, it marks the knote as influx
and drops the knlist and kqueue lock. In this context call to
kqueue_register is safe from the problems.
An error from the kqueue_register() is reported to the observer as
NOTE_TRACKERR fflag.
PR: 108201
Reviewed by: jhb, Pramod Srinivasan <pramod juniper net> (previous version)
Discussed with: jmg
Tested by: pho
MFC after: 2 weeks
KQ_FLUX_WAKEUP(). Since the later macro clears the KQ_FLUXWAIT, the
kqueue_scan() thread may be not woken up.
Move the setting of KQ_FLUXWAIT after wakeup to correct the issue.
Reported and tested by: pho
MFC after: 3 days
to global hostname and domainname variables. Where necessary, copy
to or from a stack-local buffer before performing copyin() or
copyout(). A few uses, such as in cd9660 and daemon_saver, remain
under-synchronized and will require further updates.
Correct a bug in which a failed copyin() of domainname would leave
domainname potentially corrupted.
MFC after: 3 weeks
dispatched without Giant, and add NETISR_FORCEQUEUE, which allows specific
netisr handlers to always be dispatched via a queue (deferred). Mark the
usb and if_ppp netisr handlers as NETISR_FORCEQUEUE, and explicitly
acquire Giant in those handlers.
Previously, any netisr handler not marked NETISR_MPSAFE would necessarily
run deferred and with Giant acquired. This change removes Giant
scaffolding from the netisr infrastructure, but NETISR_FORCEQUEUE allows
non-MPSAFE handlers to continue to force deferred dispatch so as to avoid
lock order reversals between their acqusition of Giant and any calling
context.
It is likely we will be able to remove NETISR_FORCEQUEUE once
IFF_NEEDSGIANT is removed, as non-MPSAFE usb and if_ppp drivers will no
longer be supported.
Reviewed by: bz
MFC after: 1 month
X-MFC note: We can't remove NETISR_MPSAFE from stable/7 for KPI reasons,
but the rest can go back.
soun->sun_path isn't a null-terminated string. As UNIX(4) states, "the
terminating NUL is not part of the address." Since strlcpy has to return
"the total length of the string [it] tried to create," it walks off the end
of soun->sun_path looking for a \0.
This reverts r105332.
Reported by: Ryan Stone
datagram-only protocols, such as UDP. This version removes use of
sblock(), which is not required due to an inability to interlace data
improperly with datagrams, as well as avoiding some of the larger loops
and state management that don't apply on datagram sockets.
This is experimental code, so hook it up only for UDPv4 for testing; if
there are problems we may need to revise it or turn it off by default,
but it offers *significant* performance improvements for threaded UDP
applications such as BIND9, nsd, and memcached using UDP.
Tested by: kris, ps
already commited but with a wrong msleep variant and then
backed out. Note that this changes the semantic a little
as msleep_spin does not let us to specify priority after
wakeup.
Approved by: wkoszek, cognet
Approved by: kib (mentor)
semaphores. Specifically, semaphores are now represented as new file
descriptor type that is set to close on exec. This removes the need for
all of the manual process reference counting (and fork, exec, and exit
event handlers) as the normal file descriptor operations handle all of
that for us nicely. It is also suggested as one possible implementation
in the spec and at least one other OS (OS X) uses this approach.
Some bugs that were fixed as a result include:
- References to a named semaphore whose name is removed still work after
the sem_unlink() operation. Prior to this patch, if a semaphore's name
was removed, valid handles from sem_open() would get EINVAL errors from
sem_getvalue(), sem_post(), etc. This fixes that.
- Unnamed semaphores created with sem_init() were not cleaned up when a
process exited or exec'd. They were only cleaned up if the process
did an explicit sem_destroy(). This could result in a leak of semaphore
objects that could never be cleaned up.
- On the other hand, if another process guessed the id (kernel pointer to
'struct ksem' of an unnamed semaphore (created via sem_init)) and had
write access to the semaphore based on UID/GID checks, then that other
process could manipulate the semaphore via sem_destroy(), sem_post(),
sem_wait(), etc.
- As part of the permission check (UID/GID), the umask of the proces
creating the semaphore was not honored. Thus if your umask denied group
read/write access but the explicit mode in the sem_init() call allowed
it, the semaphore would be readable/writable by other users in the
same group, for example. This includes access via the previous bug.
- If the module refused to unload because there were active semaphores,
then it might have deregistered one or more of the semaphore system
calls before it noticed that there was a problem. I'm not sure if
this actually happened as the order that modules are discovered by the
kernel linker depends on how the actual .ko file is linked. One can
make the order deterministic by using a single module with a mod_event
handler that explicitly registers syscalls (and deregisters during
unload after any checks). This also fixes a race where even if the
sem_module unloaded first it would have destroyed locks that the
syscalls might be trying to access if they are still executing when
they are unloaded.
XXX: By the way, deregistering system calls doesn't do any blocking
to drain any threads from the calls.
- Some minor fixes to errno values on error. For example, sem_init()
isn't documented to return ENFILE or EMFILE if we run out of semaphores
the way that sem_open() can. Instead, it should return ENOSPC in that
case.
Other changes:
- Kernel semaphores now use a hash table to manage the namespace of
named semaphores nearly in a similar fashion to the POSIX shared memory
object file descriptors. Kernel semaphores can now also have names
longer than 14 chars (up to MAXPATHLEN) and can include subdirectories
in their pathname.
- The UID/GID permission checks for access to a named semaphore are now
done via vaccess() rather than a home-rolled set of checks.
- Now that kernel semaphores have an associated file object, the various
MAC checks for POSIX semaphores accept both a file credential and an
active credential. There is also a new posixsem_check_stat() since it
is possible to fstat() a semaphore file descriptor.
- A small set of regression tests (using the ksem API directly) is present
in src/tools/regression/posixsem.
Reported by: kris (1)
Tested by: kris
Reviewed by: rwatson (lightly)
MFC after: 1 month
provides the correct semantics for flock(2) style locks which are used by the
lockf(1) command line tool and the pidfile(3) library. It also implements
recovery from server restarts and ensures that dirty cache blocks are written
to the server before obtaining locks (allowing multiple clients to use file
locking to safely share data).
Sponsored by: Isilon Systems
PR: 94256
MFC after: 2 weeks
so we cannot compile it with -fstack-protector[-all] flags (or
it will self-recurse); this is ensured in sys/conf/files. This
OTOH means that checking for defines __SSP__ and __SSP_ALL__ to
determine if we should be compiling the support is impossible
(which it was trying, resulting in an empty object file). Fix
this by always compiling the symbols in this files. It's good
because it allows us to always have SSP support, and then compile
with SSP selectively.
Repoted by: tinderbox
- It is opt-out for now so as to give it maximum testing, but it may be
turned opt-in for stable branches depending on the consensus. You
can turn it off with WITHOUT_SSP.
- WITHOUT_SSP was previously used to disable the build of GNU libssp.
It is harmless to steal the knob as SSP symbols have been provided
by libc for a long time, GNU libssp should not have been much used.
- SSP is disabled in a few corners such as system bootstrap programs
(sys/boot), process bootstrap code (rtld, csu) and SSP symbols themselves.
- It should be safe to use -fstack-protector-all to build world, however
libc will be automatically downgraded to -fstack-protector because it
breaks rtld otherwise.
- This option is unavailable on ia64.
Enable GCC stack protection (aka Propolice) for kernel:
- It is opt-out for now so as to give it maximum testing.
- Do not compile your kernel with -fstack-protector-all, it won't work.
Submitted by: Jeremie Le Hen <jeremie@le-hen.org>
locked and unlocked completely in userland. by locking and unlocking mutex
in userland, it reduces the total time a mutex is locked by a thread,
in some application code, a mutex only protects a small piece of code, the
code's execution time is less than a simple system call, if a lock contention
happens, however in current implemenation, the lock holder has to extend its
locking time and enter kernel to unlock it, the change avoids this disadvantage,
it first sets mutex to free state and then enters kernel and wake one waiter
up. This improves performance dramatically in some sysbench mutex tests.
Tested by: kris
Sounds great: jeff
FIFO, as required by SUSv3. No specific privilege check is performed
in this case, as FIFOs may be created by unprivileged processes
(subject to the normal file system name space restrictions that may be
in place).
Unlike the Apple implementation, we reject requests to create a FIFO
using mknod(2) if there is a non-zero dev argument to the system call,
which is permitted by the Open Group specification ("... undefined
..."). We might want to revise this if we find it causes
compatibility problems for applications in practice.
PR: kern/74242, kern/68459
Obtained from: Apple, Inc.
MFC after: 3 weeks
needed to promote cdev to cdev_priv, the si_priv pointer was followed.
Use member2struct() to calculate address of the wrapping cdev_priv.
Rename si_priv to __si_reserved.
Tested by: pho
Reviewed by: ed
MFC after: 2 weeks
Now that we got rid of the minor-to-unit conversion and the constraints
on device minor numbers, we can convert the functions that operate on
minor and unit numbers to simple macro's. The unit2minor() and
minor2unit() macro's are now no-ops.
The ZFS code als defined a macro named `minor'. Change the ZFS code to
use umajor() and uminor() here, as it is the correct approach to do
this. Also add $FreeBSD$ to keep SVN happy.
Approved by: philip (mentor), pjd
Except for the case where we use the cloner library (clone_create() and
friends), there is no reason to enforce a unique device minor number
policy. There are various drivers in the source tree that allocate unr
pools and such to provide minor numbers, without using them themselves.
Because we still need to support unique device minor numbers for the
cloner library, introduce a new flag called D_NEEDMINOR. All cdevsw's
that are used in combination with the cloner library should be marked
with this flag to make the cloning work.
This means drivers can now freely use si_drv0 to store their own flags
and state, making it effectively the same as si_drv1 and si_drv2. We
still keep the minor() and dev2unit() routines around to make drivers
happy.
The NTFS code also used the minor number in its hash table. We should
not do this anymore. If the si_drv0 field would be changed, it would no
longer end up in the same list.
Approved by: philip (mentor)
allocated semaphores, so it's wrong to increase it conditionally,
in this case for every over-the-limit semaphore nsegs is decreased
without being previously increased.
PR: kern/123685
Approved by: cognet (mentor)
and nfs requests processing. Lockmgr lock provides the shared locking for
nfs requests, while exclusive mode is used for modifications. The writer
starvation is handled by lockmgr too.
Reported by: kris, pho, many
Based on the submission by: mohan
Tested by: pho
MFC after: 2 weeks
The Giant lock is acquired in two places in tty_tty.c. In both places,
it is unneeded.
There is no reason to specify D_NEEDGIANT on this device node. The
device node has only been designed to return ENXIO when opened. It
doesn't make any sense to lock/unlock Giant, just to return this error.
D_TTY is also unneeded. The unimplemented functions don't need to be
patched by devfs.
We don't need to lock Giant when we want to lookup the proper TTY vnode.
s_ttyvp is already protected by proctree_lock (see devfs_vnops.c).
Approved by: philip (mentor)
Even though we got rid of device major numbers some time ago, device
drivers still need to provide unique device minor numbers to make_dev().
These numbers are only used inside the kernel. They are not related to
device major and minor numbers which are visible in devfs. These are
actually based on the inode number of the device.
It would eventually be nice to remove minor numbers entirely, but we
don't want to be too agressive here.
Because the 8-15 bits of the device number field (si_drv0) are still
reserved for the major number, there is no 1:1 mapping of the device
minor and unit numbers. Because this is now unused, remove the
restrictions on these numbers.
The MAXMAJOR definition was actually used for two purposes. It was used
to convert both the userspace and kernelspace device numbers to their
major/minor pair, which is why it is now named UMINORMASK.
minor2unit() and unit2minor() have now become useless. Both minor() and
dev2unit() now serve the same purpose. We should eventually remove some
of them, at least turning them into macro's. If devfs would become
completely minor number unaware, we could consider using si_drv0 directly,
just like si_drv1 and si_drv2.
Approved by: philip (mentor)
Right now we perform some of the checks inside the fcntl()'s F_DUPFD
operation twice. We first validate the `fd' argument. When finished,
we validate the `arg' argument. These checks are also performed inside
do_dup().
The reason we need to do this, is because fcntl() should return different
errno's when the `arg' argument is out of bounds (EINVAL instead of
EBADF). To prevent the redundant locking of the PROC_LOCK and
FILEDESC_SLOCK, patch do_dup() to support the error semantics required
by fcntl().
Approved by: philip (mentor)
Because clists are also used outside the TTY layer, rename the file
containing the clist routines to something more accurate.
The mpsafetty TTY layer doesn't use clists. It uses its own buffers,
which also implement the unbuffered copying to userspace. We cannot
simply remove the clist routines then, because this would break various
drivers that are present within the kernel.
Approved by: philip (mentor)
NET_NEEDS_GIANT. netatm has been disconnected from the build for ten
months in HEAD/RELENG_7. Specifics:
- netatm include files
- netatm command line management tools
- libatm
- ATM parts in rescue and sysinstall
- sample configuration files and documents
- kernel support as a module or in NOTES
- netgraph wrapper nodes for netatm
- ctags data for netatm.
- netatm-specific device drivers.
MFC after: 3 weeks
Reviewed by: bz
Discussed with: bms, bz, harti
refcount interface.
It also introduces the correct usage of memory barriers, as sometimes
fdrop() and fhold() are used with shared locks, which don't use any
release barrier.
ttyfree(), freeing the tty. Since destroy_dev() may call d_purge()
cdevsw method, that is the ttypurge() for the tty, the code ends up
accessing freed tty structure.
Put the ttyrel() after destroy_dev() in the ttyfree. To prevent the
panic the rev. 1.274 provided fix for, check the TS_GONE in sysctl
handler and refuse to provide information on such tty.
Reported, debugging help and tested by: pho
DIscussed with and reviewed by: jhb
MFC after: 1 week
in the giant_trick routines after the dev_refthread increments the
si_threadcount. Remove assert, do not perform dev_relthread() for failed
dev_refthread(), and handle failure in the tty_gettp() callers (cdevsw
tty methods).
Before kern_conf.c 1.210 and 1.211, the kernel usually paniced in the
giant_trick routines dereferencing NULL cdevsw, not taking this fault.
Reported by: Vince Hoffman <jhary unsane co uk>
Debugging help and tested by: pho
Reviewed by: jhb
MFC after: 1 week
