callout_stop(), except that if the callout being stopped is currently
in progress, it blocks attempts to reset the callout and waits until the
callout is completed before it returns.
This makes it possible to clean up callout-using code safely, e.g.,
without potentially freeing memory which is still being used by a callout.
Reviewed by: mux, gallatin, rwatson, jhb
count is protected by the mutex that protects the condition, so the count
does not require any extra locking or atomic operations. It serves as an
optimization to avoid calling into the sleepqueue code at all if there are
no waiters.
Note that the count can get temporarily out of sync when threads sleeping
on a condition variable time out or are aborted. However, it doesn't hurt
to call the sleepqueue code for either a signal or a broadcast when there
are no waiters, and the count is never out of sync in the opposite
direction unless we have more than INT_MAX sleeping threads.
to awaken all waiters when a contested mutex is released instead of just
the highest priority waiter. If the various threads are awakened in
sequence then each thread may acquire and release the lock in question
without contention resulting in fewer expensive unlock and lock
operations. This old behavior of waking just the highest priority is
still used if this option is specified. Making the algorithm conditional
on a kernel option will allows us to benchmark both cases later and
determine which one should be used by default.
Requested by: tanimura-san
more consistent with other APIs. sleepq and cv's use signal/broadcast, and
msleep uses wakeup_one/wakeup. Prior to this turnstiles were using a
signal/wakeup mixture.
- don't say what a small subset of the options includes are for.
- don't mark up functions which use all their args with /* ARGSUSED */.
The markup should have been removed when the unused retval parameter
was removed.
- don't comment on what routine suser() checks do. Removed nearby
excessive vertical whitespace.
SCHED_INTERACT_MAX was used where SCHED_SLP_RUN_MAX was needed. This was
causing the interactivity scaler to lose history at a more dramatic rate
than intended.
in the process. This is required for proper debugging of corefiles
created by 1:1 or M:N threaded processes. Add an XXX comment where
we should actually call a function that dumps MD specific notes.
An example of a MD specific note is the NT_PRXFPREG note for SSE
registers.
Since BFD creates non-annotated pseudo-sections for the first PRSTATUS
and FPREGSET notes (non-annotated in the sense that the name of the
section does not contain the pid/tid), make sure those sections describe
the initial thread of the process (i.e. the thread which tid equals the
pid). This is not strictly necessary, but makes sure that tools that use
the non-annotated section names will not change behaviour due to this
change.
The practical upshot of this all is that one can see the threads in
the debugger when looking at a corefile. For 1:1 threading this means
that *all* threads are visible.
is twofold:
1. When a 1:1 or M:N threaded process dumps core, we need to put the
register state of each of its kernel threads in the core file.
This can only be done by differentiating the pid field in the
respective note. For this we need the tid.
2. When thread support is present for remote debugging the kernel
with gdb(1), threads need to be identified by an integer due to
limitations in the remote protocol. This requires having a tid.
To minimize the impact of having thread IDs, threads that are created
as part of a fork (i.e. the initial thread in a process) will inherit
the process ID (i.e. tid=pid). Subsequent threads will have IDs larger
than PID_MAX to avoid interference with the pid allocation algorithm.
The assignment of tids is handled by thread_new_tid().
The thread ID allocation algorithm has been written with 3 assumptions
in mind:
1. IDs need to be created as fast a possible,
2. Reuse of IDs may happen instantaneously,
3. Someone else will write a better algorithm.
- ptrace_single_step() is no longer called with the proc lock held, so
don't try to unlock it and then relock it.
- Push Giant down into proc_rwmem() instead of forcing all the consumers
(including Alpha breakpoint support) to explicitly wrap calls to
proc_rwmem() with Giant.
Tested by: kensmith
not quite well by me - if kern.ps_argsopen was set to 0, users weren't
permitted to see arguments of even own processes.
But kern.ps_argsopen is going away, so just remove this check and leave
security checks for p_cansee() function.
declaration. Observe that initialization in declaration is
frequently incompatible with locking, not just a bad idea
due to style(9).
Submitted by: bde
and consume that interface in portalfs and fifofs instead. In the
new world order, unp_connect2() assumes that the unpcb mutex is
held, whereas uipc_connect2() validates that the passed sockets are
UNIX domain sockets, then grabs the mutex.
NB: the portalfs and fifofs code gets down and dirty with UNIX domain
sockets. Maybe this is a bad thing.
stuff was here (NFS) was fixed by Alfred in November. The only remaining
consumer of the stub functions was umapfs, which is horribly horribly
broken. It has missed out on about the last 5 years worth of maintenence
that was done on nullfs (from which umapfs is derived). It needs major
work to bring it up to date with the vnode locking protocol. umapfs really
needs to find a caretaker to bring it into the 21st century.
Functions GC'ed:
vop_noislocked, vop_nolock, vop_nounlock, vop_sharedlock.
instead of ephemeral mappings using pmap_qenter() by the writer. The
writer is still, however, responsible for wiring the pages, just not
mapping them. Consequently, the allocation of KVA for the direct case is
unnecessary. Remove it and the sysctls limiting it, i.e.,
kern.ipc.maxpipekvawired and kern.ipc.amountpipekvawired. The number
of temporarily wired pages is still, however, limited by
kern.ipc.maxpipekva.
Note: On platforms lacking a direct virtual-to-physical mapping,
uiomove_fromphys() uses sf_bufs to cache ephemeral mappings. Thus,
the number of available sf_bufs can influence the performance of pipes
on platforms such i386. Surprisingly, I saw the greatest gain from this
change on such a machine: lmbench's pipe bandwidth result increased from
~1050MB/s to ~1850MB/s on my 2.4GHz, 400MHz FSB P4 Xeon.
long as there are still explicit uses of int, whether in types or
in function names (such as atomic_set_int() in sched_ule.c), we can
not change cpumask_t to be anything other than u_int. See also the
commit log for sys/sys/types.h, revision 1.84.
activation (i.e., applications are using libpthread). This is because
SCHED_ULE sometimes puts P_SA processes into ksq_next unnecessarily.
Which doesn't give fair amount of CPU time to processes which are
using scheduler-activation-based threads when other (semi-)CPU-intensive,
non-P_SA processes are running.
Further work will no doubt be done by jeffr at a later date.
Submitted by: Taku YAMAMOTO <taku@cent.saitama-u.ac.jp>
Reviewed by: rwatson, freebsd-current@
entry size and the ELF version. Also, avoid a potential integer
overflow when determining whether the ELF header fits entirely
within the first page.
Reviewed by: jdp
A panic when attempting to execute an ELF binary with a bogus program
header table entry size was
Reported by: Christer Öberg <christer.oberg@texonet.com>
use sf_buf_free() instead of sf_buf_mext() to consolidate all actions
that require the page queues lock in one critical section. While I'm
here remove unnecessary splvm() and splx() calls.
options, status pointer and rusage pointer as arguments. It is up to
the caller to copyout the status and rusage to userland if needed. This
lets us axe the 'compat' argument and hide all that functionality in
owait(), by the way. This also cleans up some locking in kern_wait()
since it no longer has to drop locks around copyout() since all the
copyout()'s are deferred.
- Convert owait(), wait4(), and the various ABI compat wait() syscalls to
use kern_wait() rather than wait1() or wait4(). This removes a bit
more stackgap usage.
Tested on: i386
Compiled on: i386, alpha, amd64
Without this fix it is possible to cheat policies like:
- sysctl security.bsd.see_other_[gu]ids=0,
- mac_seeotheruids(4),
- jail(2)
and get full processes list with their arguments.
This problem exists from revision 1.62 of kern_proc.c when it was
introduced.
Reviewed by: nectar, rwatson.
dependent function by the same name and a machine-independent function,
sf_buf_mext(). Aside from the virtue of making more of the code machine-
independent, this change also makes the interface more logical. Before,
sf_buf_free() did more than simply undo an sf_buf_alloc(); it also
unwired and if necessary freed the page. That is now the purpose of
sf_buf_mext(). Thus, sf_buf_alloc() and sf_buf_free() can now be used
as a general-purpose emphemeral map cache.
might be enqueued on a sleep queue but not be asleep when the timeout fires
if it is blocked on a lock trying to check for pending signals before going
to sleep. In the case of fixing up the TDF_TIMEOUT race, however, the
thread must be marked asleep.
Reported by: kan (the bogus one)
Use kern_open() to implement creat() rather than taking the long route
through open(). Mark creat as MPSAFE.
While I'm at it, mark nosys() (syscall 0) as MPSAFE, for all the
difference it will make.
set it to avoid the need for a bunch of code that tests whether or
not the lock member is set to REQ_WIRED in order to determine which
length member should be used.
Fix another bug in the oldlen return value code.
Fix a potential wired memory leak if a sysctl handler uses
sysctl_wire_old_buffer() and returns an EAGAIN error to trigger
a retry.
If vslock() returns ENOMEM, sysctl_wire_old_buffer() should set
wiredlen to zero and return zero (success) so that the handler will
operate according to sysctl(3):
The size of the buffer is given by the location specified by
oldlenp before the call, and that location gives the amount
of data copied after a successful call and after a call that
returns with the error code ENOMEM.
The handler will return an ENOMEM error because the zero length
buffer will overflow.
ptrace_set_pc(), and cpu_ptrace() so that those functions are free to
acquire Giant, sleep, etc. We already do a PHOLD/PRELE around them so
that it is safe to sleep inside of these routines if necessary. This
allows ptrace() to be marked MP safe again as it no longer triggers lock
order reversals on Alpha.
Tested by: wilko
in the two consumers that need it.. processes using AIO and netncp.
Update docs. Say that process_exec is called with Giant, but not to
depend on it. All our consumers can handle it without Giant.
- no longer serialize on Giant for thread_single*() and family in fork,
exit and exec
- thread_wait() is mpsafe, assert no Giant
- reduce scope of Giant in exit to not cover thread_wait and just do
vm_waitproc().
- assert that thread_single() family are not called with Giant
- remove the DROP/PICKUP_GIANT macros from thread_single() family
- assert that thread_suspend_check() s not called with Giant
- remove manual drop_giant hack in thread_suspend_check since we know it
isn't held.
- remove the DROP/PICKUP_GIANT macros from thread_suspend_check() family
- mark kse_create() mpsafe
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.
the last chunk are misaligned relative to a MAXBSIZE byte boundary.
vn_rdwr_inchunks() is used mainly for elf core dumps, and elf sections
are usually perfectly misaligned relative to MAXBSIZE, and chunking
prevents the file system from doing much realigning.
This gives a surprisingly large speedup for core dumps -- from 50 to
13 seconds for a 512MB core dump here. The pessimization was mostly
from an interaction of the misalignment with IO_DIRECT. It increased
the number of i/o's for each chunk by a factor of 5 (3 writes and 2
read-before-writes instead of 1 write).
to build the kernel. It doesn't affect the operation if gcc.
Most of the changes are just adding __INTEL_COMPILER to #ifdef's, as
icc v8 may define __GNUC__ some parts may look strange but are
necessary.
Additional changes:
- in_cksum.[ch]:
* use a generic C version instead of the assembly version in the !gcc
case (ASM code breaks with the optimizations icc does)
-> no bad checksums with an icc compiled kernel
Help from: andre, grehan, das
Stolen from: alpha version via ppc version
The entire checksum code should IMHO be replaced with the DragonFly
version (because it isn't guaranteed future revisions of gcc will
include similar optimizations) as in:
---snip---
Revision Changes Path
1.12 +1 -0 src/sys/conf/files.i386
1.4 +142 -558 src/sys/i386/i386/in_cksum.c
1.5 +33 -69 src/sys/i386/include/in_cksum.h
1.5 +2 -0 src/sys/netinet/igmp.c
1.6 +0 -1 src/sys/netinet/in.h
1.6 +2 -0 src/sys/netinet/ip_icmp.c
1.4 +3 -4 src/contrib/ipfilter/ip_compat.h
1.3 +1 -2 src/sbin/natd/icmp.c
1.4 +0 -1 src/sbin/natd/natd.c
1.48 +1 -0 src/sys/conf/files
1.2 +0 -1 src/sys/conf/files.amd64
1.13 +0 -1 src/sys/conf/files.i386
1.5 +0 -1 src/sys/conf/files.pc98
1.7 +1 -1 src/sys/contrib/ipfilter/netinet/fil.c
1.10 +2 -3 src/sys/contrib/ipfilter/netinet/ip_compat.h
1.10 +1 -1 src/sys/contrib/ipfilter/netinet/ip_fil.c
1.7 +1 -1 src/sys/dev/netif/txp/if_txp.c
1.7 +1 -1 src/sys/net/ip_mroute/ip_mroute.c
1.7 +1 -2 src/sys/net/ipfw/ip_fw2.c
1.6 +1 -2 src/sys/netinet/igmp.c
1.4 +158 -116 src/sys/netinet/in_cksum.c
1.6 +1 -1 src/sys/netinet/ip_gre.c
1.7 +1 -2 src/sys/netinet/ip_icmp.c
1.10 +1 -1 src/sys/netinet/ip_input.c
1.10 +1 -2 src/sys/netinet/ip_output.c
1.13 +1 -2 src/sys/netinet/tcp_input.c
1.9 +1 -2 src/sys/netinet/tcp_output.c
1.10 +1 -1 src/sys/netinet/tcp_subr.c
1.10 +1 -1 src/sys/netinet/tcp_syncache.c
1.9 +1 -2 src/sys/netinet/udp_usrreq.c
1.5 +1 -2 src/sys/netinet6/ipsec.c
1.5 +1 -2 src/sys/netproto/ipsec/ipsec.c
1.5 +1 -1 src/sys/netproto/ipsec/ipsec_input.c
1.4 +1 -2 src/sys/netproto/ipsec/ipsec_output.c
and finally remove
sys/i386/i386 in_cksum.c
sys/i386/include in_cksum.h
---snip---
- endian.h:
* DTRT in C++ mode
- quad.h:
* we don't use gcc v1 anymore, remove support for it
Suggested by: bde (long ago)
- assym.h:
* avoid zero-length arrays (remove dependency on a gcc specific
feature)
This change changes the contents of the object file, but as it's
only used to generate some values for a header, and the generator
knows how to handle this, there's no impact in the gcc case.
Explained by: bde
Submitted by: Marius Strobl <marius@alchemy.franken.de>
- aicasm.c:
* minor change to teach it about the way icc spells "-nostdinc"
Not approved by: gibbs (no reply to my mail)
- bump __FreeBSD_version (lang/icc needs to know about the changes)
Incarnations of this patch survive gcc compiles since a loooong time,
I use it on my desktop. An icc compiled kernel works since Nov. 2003
(exceptions: snd_* if used as modules), it survives a build of the
entire ports collection with icc.
Parts of this commit contains suggestions or submissions from
Marius Strobl <marius@alchemy.franken.de>.
Reviewed by: -arch
Submitted by: netchild
Conforming POSIX application should do by disallowing the argv
argument to be NULL.
PR: kern/33738
Submitted by: Marc Olzheim, Serge van den Boom
OK'ed by: nectar
silences an annoying warning in getblk() when VMIO'ing on a directory
vnode, which can happen when vfs.vmiodirenable is 1.
Bring the warning message in line with reality at the same time.
Submitted by: hmp
were a rather overwhelming task. I soon learned that if you don't know
where you're going to store something, at least try to pile it next to
something slightly related in the hope that a pattern emerges.
Apply the same principle to the ffs/snapshot/softupdates code which have
leaked into specfs: Add yet a buf-quasi-method and call it from the
only two places I can see it can make a difference and implement the
magic in ffs_softdep.c where it belongs.
It's not pretty, but at least it's one less layer violated.
- security.bsd.hardlink_check_uid, when set, means, that unprivileged
users are not permitted to create hard links to files not
owned by them,
- security.bsd.hardlink_check_gid, when set, means, that unprivileged
users are not permitted to create hard links to files owned
by group they don't belong to.
OK'ed by: rwatson
that we (p1) are currently running, we hold a reference on p_textvp which
means the vnode cannot go away. p2 cannot run yet (and hence cannot exit)
so this should be safe to do at this point. As a bonus, it removes a
block of under-Giant code that was there to support the vref.
- Push Giant down a bit in coredump() and call coredump() with the proc
lock already held rather than unlocking it only to turn around and
relock it.
Requested by: peter
process group and session dereferences. Also, check that p_pgrp and
p_sesssion are NULL before dereferencing them.
- Push down Giant in fork1().
Requested by: peter
introduction of kern_mlock() and kern_munlock() in
src/sys/kern/kern_sysctl.c 1.150
src/sys/vm/vm_extern.h 1.69
src/sys/vm/vm_glue.c 1.190
src/sys/vm/vm_mmap.c 1.179
because different resource limits are appropriate for transient and
"permanent" page wiring requests.
Retain the kern_mlock() and kern_munlock() API in the revived
vslock() and vsunlock() functions.
Combine the best parts of each of the original sets of implementations
with further code cleanup. Make the mclock() and vslock()
implementations as similar as possible.
Retain the RLIMIT_MEMLOCK check in mlock(). Move the most strigent
test, which can return EAGAIN, last so that requests that have no
hope of ever being satisfied will not be retried unnecessarily.
Disable the test that can return EAGAIN in the vslock() implementation
because it will cause the sysctl code to wedge.
Tested by: Cy Schubert <Cy.Schubert AT komquats.com>
DIAGNOSTIC instead of INVARIANTS. INVARIANTS is intended for tests
that don't substantially change code flow or behavior (passive), but
this test required locking both the proc lock and scheduler lock
in order to execute. It also appears to be a very advisory diagnostic
as opposed to an invariant violation.
Following discussion with: bde
race in between sleepq_add() and sleepq_catch_signals() in that setting
td_wchan and TDF_SINTR is not atomic to sched_lock but only to the sleepq
lock. This band-aid will stop assertion failures, but there is perhaps a
larger problem with the sleepq_add/sleepq_catch_signals race that I am not
sure how to solve. For the signals case the race is harmless because we
always call cursig() after setting TDF_SINTR. However, KSE doesn't do
anything in sleepq_catch_signals() to check that this race was lost, so I
am unsure if this race is harmful for this specific abort.
functions in kern_socket.c.
Rename the "canwait" field to "mflags" and pass M_WAITOK and M_NOWAIT
in from the caller context rather than "1" or "0".
Correct mflags pass into mac_init_socket() from previous commit to not
include M_ZERO.
Submitted by: sam
than a "waitok" argument. Callers now passing M_WAITOK or M_NOWAIT
rather than 0 or 1. This simplifies the soalloc() logic, and also
makes the waiting behavior of soalloc() more clear in the calling
context.
Submitted by: sam
generic watchdoc(9) interface.
Make watchdogd(8) perform as watchdog(8) as well, and make it
possible to specify a check command to run, timeout and sleep
periods.
Update watchdog(4) to talk about the generic interface and add
new watchdog(8) page.
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.
the process state to zombie when a process exits to avoid a lock order
reversal with the sleepqueue locks. This appears to be the only place
that we call wakeup() with sched_lock held.
to queue threads sleeping on a wait channel similar to how turnstiles are
used to queue threads waiting for a lock. This subsystem will be used as
the backend for sleep/wakeup and condition variables initially. Eventually
it will also be used to replace the ithread-specific iwait thread
inhibitor.
Sleep queues are also not locked by sched_lock, so this splits sched_lock
up a bit further increasing concurrency within the scheduler. Sleep queues
also natively support timeouts on sleeps and interruptible sleeps allowing
for the reduction of a lot of duplicated code between the sleep/wakeup and
condition variable implementations. For more details on the sleep queue
implementation, check the comments in sys/sleepqueue.h and
kern/subr_sleepqueue.c.
the syscall arguments and does the suser() permission check, and
kern_mlock(), which does the resource limit checking and calls
vm_map_wire(). Split munlock() in a similar way.
Enable the RLIMIT_MEMLOCK checking code in kern_mlock().
Replace calls to vslock() and vsunlock() in the sysctl code with
calls to kern_mlock() and kern_munlock() so that the sysctl code
will obey the wired memory limits.
Nuke the vslock() and vsunlock() implementations, which are no
longer used.
Add a member to struct sysctl_req to track the amount of memory
that is wired to handle the request.
Modify sysctl_wire_old_buffer() to return an error if its call to
kern_mlock() fails. Only wire the minimum of the length specified
in the sysctl request and the length specified in its argument list.
It is recommended that sysctl handlers that use sysctl_wire_old_buffer()
should specify reasonable estimates for the amount of data they
want to return so that only the minimum amount of memory is wired
no matter what length has been specified by the request.
Modify the callers of sysctl_wire_old_buffer() to look for the
error return.
Modify sysctl_old_user to obey the wired buffer length and clean up
its implementation.
Reviewed by: bms
of all, PIPE_EOF is not checked pervasively after everything that can drop
the pipe mutex and msleep(), so fix. Additionally, though it might not
harm anything, pipelock() and pipeunlock() are not used consistently.
Third, the kqueue support functions do not use the pipe mutex correctly.
Last, but absolutely not least, is a race: if pipe_busy is not set on
the closing side of the pipe, the other side that is trying to write to
that will crash BECAUSE PIPE_EOF IS NOT SET! Unconditionally set
PIPE_EOF, and get rid of all the lockups/crashes I have seen trying
to build ports.
Now I believe it is done in the right way.
Removed some XXMAC cases, we now assume 'high' integrity level for all
sysctls, except those with CTLFLAG_ANYBODY flag set. No more magic.
Reviewed by: rwatson
Approved by: rwatson, scottl (mentor)
Tested with: LINT (compilation), mac_biba(4) (functionality)
to use the "year1-year3" format, as opposed to "year1, year2, year3".
This seems to make lawyers more happy, but also prevents the
lines from getting excessively long as the years start to add up.
Suggested by: imp
This is what we came here for: Hang dev_t's from their cdevsw,
refcount cdevsw and dev_t and generally keep track of things a lot
better than we used to:
Hold a cdevsw reference around all entrances into the device driver,
this will be necessary to safely determine when we can unload driver
code.
Hold a dev_t reference while the device is open.
KASSERT that we do not enter the driver on a non-referenced dev_t.
Remove old D_NAG code, anonymous dev_t's are not a problem now.
When destroy_dev() is called on a referenced dev_t, move it to
dead_cdevsw's list. When the refcount drops, free it.
Check that cdevsw->d_version is correct. If not, set all methods
to the dead_*() methods to prevent entrance into driver. Print
warning on console to this effect. The device driver may still
explode if it is also incompatible with newbus, but in that case
we probably didn't get this far in the first place.
Remove the unused second argument from udev2dev().
Convert all remaining users of makedev() to use udev2dev(). The
semantic difference is that udev2dev() will only locate a pre-existing
dev_t, it will not line makedev() create a new one.
Apart from the tiny well controlled windown in D_PSEUDO drivers,
there should no longer be any "anonymous" dev_t's in the system
now, only dev_t's created with make_dev() and make_dev_alias()
Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.
Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.
Add missing D_TTY flags to various drivers.
Complete asserts that dev_t's passed to ttyread(), ttywrite(),
ttypoll() and ttykqwrite() have (d_flags & D_TTY) and a struct tty
pointer.
Make ttyread(), ttywrite(), ttypoll() and ttykqwrite() the default
cdevsw methods for D_TTY drivers and remove the explicit initializations
in various drivers cdevsw structures.
This commit adds a couple of functions for pseudodrivers to use for
implementing cloning in a manner we will be able to lock down (shortly).
Basically what happens is that pseudo drivers get a way to ask for
"give me the dev_t with this unit number" or alternatively "give
me a dev_t with the lowest guaranteed free unit number" (there is
unfortunately a lot of non-POLA in the exact numeric value of this
number, just live with it for now)
Managing the unit number space this way removes the need to use
rman(9) to do so in the drivers this greatly simplifies the code in
the drivers because even using rman(9) they still needed to manage
their dev_t's anyway.
I have taken the if_tun, if_tap, snp and nmdm drivers through the
mill, partly because they (ab)used makedev(), but mostly because
together they represent three different problems for device-cloning:
if_tun and snp is the plain case: just give me a device.
if_tap has two kinds of devices, with a flag for device type.
nmdm has paired devices (ala pty) can you can clone either of them.
Instead of creating a mutex that we msleep on but don't actually lock when
doing the corresponding wakeup(), in the kthread, lock the mutex associated
with our taskqueue and msleep while the queue is empty. Assert that the
queue is locked when the callback function is called to wake the kthread.
It returns 1 is process is inside of jail and 0 if it is not.
Information if we are in jail or not is not a secret, there is plenty of
ways to discover it. Many people are using own hack to check this and
this will be a legal way from now on.
It will be great if our starting scripts will take advantage of this sysctl
to allow clean "boot" inside jail.
Approved by: rwatson, scottl (mentor)
