Commit Graph

14946 Commits

Author SHA1 Message Date
trasz
aea1562f16 Add new unmount(2) flag, MNT_NONBUSY, to check whether there are
any open vnodes before proceeding. Make autounmound(8) use this flag.
Without it, even an unsuccessfull unmount causes filesystem flush,
which interferes with normal operation.

Reviewed by:	kib@
Approved by:	re (gjb@)
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D7047
2016-07-07 09:03:57 +00:00
nwhitehorn
89d01c24d1 Replace a number of conflations of mp_ncpus and mp_maxid with either
mp_maxid or CPU_FOREACH() as appropriate. This fixes a number of places in
the kernel that assumed CPU IDs are dense in [0, mp_ncpus) and would try,
for example, to run tasks on CPUs that did not exist or to allocate too
few buffers on systems with sparse CPU IDs in which there are holes in the
range and mp_maxid > mp_ncpus. Such circumstances generally occur on
systems with SMT, but on which SMT is disabled. This patch restores system
operation at least on POWER8 systems configured in this way.

There are a number of other places in the kernel with potential problems
in these situations, but where sparse CPU IDs are not currently known
to occur, mostly in the ARM machine-dependent code. These will be fixed
in a follow-up commit after the stable/11 branch.

PR:		kern/210106
Reviewed by:	jhb
Approved by:	re (glebius)
2016-07-06 14:09:49 +00:00
glebius
2b2f782761 The paradigm of a callout is that it has three consequent states:
not scheduled -> scheduled -> running -> not scheduled. The API and the
manual page assume that, some comments in the code assume that, and looks
like some contributors to the code also did. The problem is that this
paradigm isn't true. A callout can be scheduled and running at the same
time, which makes API description ambigouous. In such case callout_stop()
family of functions/macros should return 1 and 0 at the same time, since it
successfully unscheduled future callout but the current one is running.
Before this change we returned 1 in such a case, with an exception that
if running callout was migrating we returned 0, unless CS_MIGRBLOCK was
specified.

With this change, we now return 0 in case if future callout was unscheduled,
but another one is still in action, indicating to API users that resources
are not yet safe to be freed.

However, the sleepqueue code relies on getting 1 return code in that case,
and there already was CS_MIGRBLOCK flag, that covered one of the edge cases.
In the new return path we will also use this flag, to keep sleepqueue safe.

Since the flag CS_MIGRBLOCK doesn't block migration and now isn't limited to
migration edge case, rename it to CS_EXECUTING.

This change fixes panics on a high loaded TCP server.

Reviewed by:	jch, hselasky, rrs, kib
Approved by:	re (gjb)
Differential Revision:	https://reviews.freebsd.org/D7042
2016-07-05 18:47:17 +00:00
glebius
0417c9be8f Compile in the kassert_panic() function with INVARIANT_SUPPORT
option, not INVARIANTS.  The function is required if we want
to load in a module that is compiled with INVARIANTS.

Reviewed by:	jhb
Approved by:	re (gjb)
2016-07-05 18:34:34 +00:00
markj
d6ae30f932 Ensure that spinlock sections are balanced even after a panic.
vpanic() uses spinlock_enter() to disable interrupts before dumping core.
However, when the scheduler is stopped and INVARIANTS is not configured,
thread_lock() does not acquire a spinlock section, while thread_unlock()
releases one. This can result in interrupts staying enabled while the
kernel dumps core, complicating post-mortem analysis of the crash.

Approved by:	re (gjb)
MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
2016-07-05 17:59:04 +00:00
rwatson
0696f7cf29 Call audit hooks to capture vnode attributes for three file-descriptor
method implementations: fstat(2), close(2), and poll(2).  This change
synchronises auditing here with similar auditing for VFS-specific system
calls such as stat(2) that audit more complete vnode information.

Sponsored by:	DARPA, AFRL
Approved by:	re (kib)
MFC after:	1 week
2016-07-05 16:37:01 +00:00
emaste
c769866ed1 add description for debug.elf{32,64}_legacy_coredump sysctl
Approved by:	re (kib)
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
2016-07-05 14:46:06 +00:00
kib
2ff8e9c636 Provide helper macros to detect 'non-silent SBDRY' state and to
calculate appropriate return value for stops.  Simplify the code by
using them.

Fix typo in sig_suspend_threads().  The thread which sleep must be
aborted is td2. (*)

In issignal(), when handling stopping signal for thread in
TD_SBDRY_INTR state, do not stop, this is wrong and fires assert.
This is yet another place where execution should be forced out of
SBDRY-protected region.  For such case, return -1 from issignal() and
translate it to corresponding error code in sleepq_catch_signals().
Assert that other consumers of cursig() are not affected by the new
return value. (*)

Micro-optimize, mostly VFS and VOP methods, by avoiding calling the
functions when SIGDEFERSTOP_NOP non-change is requested. (**)

Reported and tested by:	pho (*)
Requested by:	bde (**)
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)
2016-07-03 18:19:48 +00:00
kib
c31bb3499e Remove racy assert. The thread which changes vnode usecount from 0 to 1
does it under the vnode interlock, but the interlock is not owned by the
asserting thread.  As result, we might read increased use counter but also
still see VI_OWEINACT.

In collaboration with: nwhitehorn
Hardware donated by: IBM LTC
Sponsored by:	The FreeBSD Foundation (kib)
Approved by:	re (gjb)
2016-07-03 01:56:48 +00:00
kib
38d067a317 When a process knote was attached to the process which is already exiting,
the knote is activated immediately.  If the exit1() later activates
knotes, such knote is attempted to be activated second time.  Detect
the condition by zeroed kn_ptr.p_proc pointer, and avoid excessive
activation.

Before r302235, such knotes were removed from the knlist immediately
upon activation.

Reported by:	truckman
Sponsored by:	The FreeBSD Foundation
Approved by:	re (gjb)
2016-07-01 20:11:28 +00:00
kib
42d92058c3 Currently the ntptime code and resettodr() are Giant-locked. In
particular, the Giant is supposed to protect against parallel
ntp_adjtime(2) invocations.  But, for instance, sys_ntp_adjtime() does
copyout(9) under Giant and then examines time_status to return syscall
result.  Since copyout(9) could sleep, the syscall result might be
inconsistent.

Another and more important issue is that if PPS is configured,
hardpps(9) is executed without any protection against the parallel
top-level code invocation. Potentially, this may result in the
inconsistent state of the ntptime state variables, but I cannot say
how serious such distortion is. The non-functional splclock() call in
sys_ntp_adjtime() protected against clock interrupts calling hardpps()
in the pre-SMP era.

Modernize the locking. A mutex protects ntptime data.  Due to the
hardpps() KPI legitimately serving from the interrupt filters (and
e.g. uart(4) does call it from filter), the lock cannot be sleepable
mutex if PPS_SYNC is defined.  Otherwise, use normal sleepable mutex
to reduce interrupt latency.

Reviewed by:	  imp, jhb
Sponsored by:	  The FreeBSD Foundation
Approved by:	  re (gjb)
Differential revision:	https://reviews.freebsd.org/D6825
2016-06-28 16:43:23 +00:00
kib
8543a46c50 Do not use Giant to prevent parallel calls to CLOCK_SETTIME(). Use
private mtx in resettodr(), no implementation of CLOCK_SETTIME() is
allowed to sleep.

Reviewed by:	  imp, jhb
Sponsored by:	  The FreeBSD Foundation
Approved by:	  re (gjb)
X-Differential revision:	https://reviews.freebsd.org/D6825
2016-06-28 16:42:40 +00:00
kib
fb3ea99e64 Complete r302215. TDF_SBDRY | TDF_SERESTART and TDF_SBDRY |
TDF_SEINTR flags values, unlike TDF_SBDRY, must be treated almost as
if TDF_SBDRY is not set for STOP signal delivery.  The only difference
is that sig_suspend_threads() should abort the sleep instead of doing
immediate suspension.

Reported by:	ngie
Sponsored by:	The FreeBSD Foundation
MFC after:	12 days
Approved by:	re (gjb)
2016-06-28 16:41:50 +00:00
kib
8dad8cb1ad Fix userspace build after r302235: do not expose bool field of the
structure, change it to int.

The real fix is to sanitize user-visible definitions in sys/event.h,
e.g. the affected struct knlist is of no use for userspace programs.

Reported and tested by:	jkim
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)
2016-06-27 23:34:53 +00:00
kib
15841a7afe When filt_proc() removes event from the knlist due to the process
exiting (NOTE_EXIT->knlist_remove_inevent()), two things happen:
- knote kn_knlist pointer is reset
- INFLUX knote is removed from the process knlist.
And, there are two consequences:
- KN_LIST_UNLOCK() on such knote is nop
- there is nothing which would block exit1() from processing past the
  knlist_destroy() (and knlist_destroy() resets knlist lock pointers).
Both consequences result either in leaked process lock, or
dereferencing NULL function pointers for locking.

Handle this by stopping embedding the process knlist into struct proc.
Instead, the knlist is allocated together with struct proc, but marked
as autodestroy on the zombie reap, by knlist_detach() function.  The
knlist is freed when last kevent is removed from the list, in
particular, at the zombie reap time if the list is empty.  As result,
the knlist_remove_inevent() is no longer needed and removed.

Other changes:

In filt_procattach(), clear NOTE_EXEC and NOTE_FORK desired events
from kn_sfflags for knote registered by kernel to only get NOTE_CHILD
notifications.  The flags leak resulted in excessive
NOTE_EXEC/NOTE_FORK reports.

Fix immediate note activation in filt_procattach().  Condition should
be either the immediate CHILD_NOTE activation, or immediate NOTE_EXIT
report for the exiting process.

In knote_fork(), do not perform racy check for KN_INFLUX before kq
lock is taken.  Besides being racy, it did not accounted for notes
just added by scan (KN_SCAN).

Some minor and incomplete style fixes.

Analyzed and tested by:	Eric Badger <eric@badgerio.us>
Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)
Differential revision:	https://reviews.freebsd.org/D6859
2016-06-27 21:52:17 +00:00
kib
13c308de0c When sleeping waiting for either local or remote advisory lock,
interrupt sleeps with the ERESTART on the suspension attempts.
Otherwise, single-threading requests are deferred until the locks are
granted for NFS files, which causes hangs.

When retrying local registration of the remotely-granted adv lock,
allow full suspension and check for suspension, for usual reasons.

Reported by:	markj, pho
Reviewed by:	jilles
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)
2016-06-26 20:08:42 +00:00
kib
2b281bf08f Rewrite sigdeferstop(9) and sigallowstop(9) into more flexible
framework allowing to set the suspension policy for the dynamic block.
Extend the currently possible policies of stopping on interruptible
sleeps and ignoring such sleeps by two more: do not suspend at
interruptible sleeps, but interrupt them with either EINTR or ERESTART.

Reviewed by:	jilles
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)
2016-06-26 20:07:24 +00:00
kib
72cb649e6e Do not clear robust lists pointers on fork. The forked child thread
lists must be functional.

Reported by:	Daniel Engberg <daniel.engberg.lists@pyret.net>,
	Guy Yur <guyyur@gmail.com>
Tested by:	Guy Yur <guyyur@gmail.com>
Sponsored by:	The FreeBSD Foundation
Approved by:	re (gjb), including the KBI change
2016-06-25 11:31:25 +00:00
jilles
0c4cfbe0d1 posixshm: Fix lock leak when mac_posixshm_check_read rejects read.
While reading the code, I noticed that shm_read() returns without unlocking
foffset and rangelock if mac_posixshm_check_read() rejects the read.

Reviewed by:	kib, jhb, rwatson
Approved by:	re (gjb)
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D6927
2016-06-23 20:59:13 +00:00
brooks
251cde9f5a Generate syscall tables and update pipe() implementation after r302094.
Mark the pipe() system call as COMPAT10.

As of r302092 libc uses pipe2() with a zero flags value instead of pipe().

Approved by:	re (gjb)
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D6816
2016-06-22 21:18:19 +00:00
brooks
e4ef2142c8 Mark the pipe() system call as COMPAT10.
As of r302092 libc uses pipe2() with a zero flags value instead of pipe().

Commit with regenerated files and implementation to follow.

Approved by:	re (gjb)
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D6816
2016-06-22 21:15:59 +00:00
brooks
a11d117db1 Add support for COMPAT10 keywords in syscalls.master.
Approved by:	re (gjb)
Sponsored by:	DARPA, AFRL
2016-06-22 21:12:53 +00:00
jhb
a6270457f8 Account for AIO socket operations in thread/process resource usage.
File and disk-backed I/O requests store counts of read/written disk
blocks in each AIO job so that they can be charged to the thread that
completes an AIO request via aio_return() or aio_waitcomplete().  This
change extends AIO jobs to store counts of received/sent messages and
updates socket backends to set these counts accordingly.  Note that
the socket backends are careful to only charge a single messages for
each AIO request even though a single request on a blocking socket might
invoke sosend or soreceive multiple times.  This is to mimic the
resource accounting of synchronous read/write.

Adjust the UNIX socketpair AIO test to verify that the message resource
usage counts update accordingly for aio_read and aio_write.

Approved by:	re (hrs)
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D6911
2016-06-21 22:19:06 +00:00
bz
7a1c0b1ad1 Get closer to a VIMAGE network stack teardown from top to bottom rather
than removing the network interfaces first. This change is rather larger
and convoluted as the ordering requirements cannot be separated.

Move the pfil(9) framework to SI_SUB_PROTO_PFIL, move Firewalls and
related modules to their own SI_SUB_PROTO_FIREWALL.
Move initialization of "physical" interfaces to SI_SUB_DRIVERS,
move virtual (cloned) interfaces to SI_SUB_PSEUDO.
Move Multicast to SI_SUB_PROTO_MC.

Re-work parts of multicast initialisation and teardown, not taking the
huge amount of memory into account if used as a module yet.

For interface teardown we try to do as many of them as we can on
SI_SUB_INIT_IF, but for some this makes no sense, e.g., when tunnelling
over a higher layer protocol such as IP. In that case the interface
has to go along (or before) the higher layer protocol is shutdown.

Kernel hhooks need to go last on teardown as they may be used at various
higher layers and we cannot remove them before we cleaned up the higher
layers.

For interface teardown there are multiple paths:
(a) a cloned interface is destroyed (inside a VIMAGE or in the base system),
(b) any interface is moved from a virtual network stack to a different
network stack ("vmove"), or (c) a virtual network stack is being shut down.
All code paths go through if_detach_internal() where we, depending on the
vmove flag or the vnet state, make a decision on how much to shut down;
in case we are destroying a VNET the individual protocol layers will
cleanup their own parts thus we cannot do so again for each interface as
we end up with, e.g., double-frees, destroying locks twice or acquiring
already destroyed locks.
When calling into protocol cleanups we equally have to tell them
whether they need to detach upper layer protocols ("ulp") or not
(e.g., in6_ifdetach()).

Provide or enahnce helper functions to do proper cleanup at a protocol
rather than at an interface level.

Approved by:		re (hrs)
Obtained from:		projects/vnet
Reviewed by:		gnn, jhb
Sponsored by:		The FreeBSD Foundation
MFC after:		2 weeks
Differential Revision:	https://reviews.freebsd.org/D6747
2016-06-21 13:48:49 +00:00
kib
06125ebef5 Fix typo. Note that atomic is still required even for interlocked case.
Sponsored by:	The FreeBSD Foundation
Approved by:	re (marius)
2016-06-20 15:45:50 +00:00
mjg
ed393257f0 vfs: ifdef out noop vop_* primitives on !DEBUG_VFS_LOCKS kernels
This removes calls to empty functions like vop_lock_{pre/post} from
common vfs routines.

Approved by:	re (gjb)
2016-06-17 19:41:30 +00:00
kib
40488ecf84 Add VFS interface to flush specified amount of free vnodes belonging
to mount points with the given filesystem type, specified by mount
vfs_ops pointer.

Based on patch by:	mckusick
Reviewed by:	avg, mckusick
Tested by:	allanjude, madpilot
Sponsored by:	The FreeBSD Foundation
Approved by:	re (gjb)
2016-06-17 17:33:25 +00:00
kib
496a3b1f65 Update comments for the MD functions managing contexts for new
threads, to make it less confusing and using modern kernel terms.

Rename the functions to reflect current use of the functions, instead
of the historic KSE conventions:
  cpu_set_fork_handler -> cpu_fork_kthread_handler (for kthreads)
  cpu_set_upcall -> cpu_copy_thread (for forks)
  cpu_set_upcall_kse -> cpu_set_upcall (for new threads creation)

Reviewed by:	jhb (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (hrs)
Differential revision:	https://reviews.freebsd.org/D6731
2016-06-16 12:05:44 +00:00
kib
2c44599f9c Remove XXX comments from kern_thread.c. In one case, there is no
reason for it in modern times.  In the other case, expand the comment
stating instead of doubting.

Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (hrs)
X-Differential revision:	https://reviews.freebsd.org/D6731
2016-06-16 12:01:11 +00:00
kib
aea5f52dbc Remove code duplication.
Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (hrs)
X-Differential revision:	https://reviews.freebsd.org/D6731
2016-06-16 11:58:46 +00:00
jhb
593d3fb218 Move backend-specific fields of kaiocb into a union.
This reduces the size of kaiocb slightly. I've also added some generic
fields that other backends can use in place of the BIO-specific fields.

Change the socket and Chelsio DDP backends to use 'backend3' instead of
abusing _aiocb_private.status directly. This confines the use of
_aiocb_private to the AIO internals in vfs_aio.c.

Reviewed by:	kib (earlier version)
Approved by:	re (gjb)
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D6547
2016-06-15 20:56:45 +00:00
kib
22f8dd6d9b Do not assume that we own the use reference on the covered vnode until
we set MNTK_UNMOUNT flag on the mp.  Otherwise parallel unmount which
wins race with us could dereference the covered vnode, and we are
left with the locked freed memory.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
Approved by:	re (gjb)
MFC after:	1 week
2016-06-15 15:56:03 +00:00
jamie
aad828cb49 Fix a vnode leak when giving a child jail a too-long path when
debug.disablefullpath=1.
2016-06-09 21:59:11 +00:00
jamie
786e18e298 Re-order some jail parameter reading to prevent a vnode leak. 2016-06-09 20:43:14 +00:00
jamie
91dc125e2d Clean up some logic in jail error messages, replacing a missing test and
a redundant test with a single correct test.
2016-06-09 20:39:57 +00:00
oshogbo
57dc7171d0 Define tunable instead of using CTLFLAG_RWTUN flag with kern.corefile.
The allproc_lock lock used in the sysctl_kern_corefile function is initialized
in the procinit function which is called after setting sysctl values at boot.
That means if we set kern.corefile at boot we will be trying to use
lock with is uninitialized and machine will crash.

If we define kern.corefile as tunable instead of using CTFLAG_RWTUN we will
not call the sysctl_kern_corefile function and we will not use an uninitialized
lock. When machine will boot then we will start using function depending on
the lock.

Reviewed by:	pjd
2016-06-09 20:23:30 +00:00
cem
a9972a75af Add DDB command "kldstat"
It prints much the same information as kldstat(8) without any arguments.

Suggested by:	jhibbits
Sponsored by:	EMC / Isilon Storage Division
2016-06-09 18:27:41 +00:00
cem
5ebc37ce13 kvprintf: Pad %*c to width, like %*s
Sponsored by:	EMC / Isilon Storage Division
2016-06-09 18:24:51 +00:00
jamie
debe558799 Make sure the OSD methods for jail set and remove can't run concurrently,
by holding allprison_lock exclusively (even if only for a moment before
downgrading) on all paths that call PR_METHOD_REMOVE.  Since they may run
on a downgraded lock, it's still possible for them to run concurrently
with PR_METHOD_GET, which will need to use the prison lock.
2016-06-09 16:41:41 +00:00
jamie
88eec3fa5b Remove a comment that was part of copied code, and is misleading in
the new location.
2016-06-09 15:34:33 +00:00
markj
cdf94f56b0 Fix some cosmetic issues in kern_fail.c omitted from r296927.
Obtained from:	Matthew Bryan <matthew.bryan@isilon.com>
2016-06-09 13:17:08 +00:00
kib
ef4ada7b76 Old process credentials for setuid execve must not be dereferenced
when the process credentials were not changed.  This can happen if an
error occured trying to activate the setuid binary.  And on error, if
new credentials were not yet assigned, they must be freed to not
create the leak.

Use oldcred == NULL as the predicate to detect credential
reassignment.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
2016-06-08 04:37:03 +00:00
oshogbo
17ff1e5b26 Introduce the PD_CLOEXEC for pdfork(2).
Reviewed by:	mjg
2016-06-08 02:09:14 +00:00
skra
707fd866b9 Remove temporary solution for storing interrupt mapping data as
it's not needed after r301451 and follow-ups r301453, r301539.

This makes INTRNG clean of all additions related to various buses.
2016-06-07 09:03:27 +00:00
mmel
f66cc0d4f8 INTRNG: As follow up of r301451, implement mapping and configuration
of gpio pin interrupts by new way.

Note: This removes last consumer of intr_ddata machinery and we remove it
in separate commit.
2016-06-07 05:08:24 +00:00
bz
2919ef7927 Implement a show panic command to DDB which will helpfully print the
panic string again if set, in case it scrolled out of the active
window.  This avoids having to remember the symbol name.

Also add a show callout <addr> command to DDB in order to inspect
some struct callout fields in case of panics in the callout code.
This may help to see if there was memory corruption or to further
ease debugging problems.

Obtained from:	projects/vnet
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Reviewed by:	jhb (comment only on the show panic initally)
Differential Revision:	https://reviews.freebsd.org/D4527
2016-06-06 20:57:24 +00:00
kib
ef5f88c357 Get rid of struct proc p_sched and struct thread td_sched pointers.
p_sched is unused.

The struct td_sched is always co-allocated with the struct thread,
except for the thread0.  Avoid useless indirection, instead calculate
td_sched location using simple pointer arithmetic in td_get_sched(9).
For thread0, which is statically allocated, create a structure to
emulate layout of the dynamic allocation.

Reviewed by:	jhb (previous version)
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D6711
2016-06-05 17:04:03 +00:00
kib
78ad2d6695 Use ANSI function definition.
Sponsored by:	The FreeBSD Foundation
2016-06-05 16:55:55 +00:00
skra
612e6958e4 INTRNG - change the way how an interrupt mapping data are provided
to the framework in OFW (FDT) case.

This is a follow-up to r301451.

Differential Revision:	https://reviews.freebsd.org/D6634
2016-06-05 16:20:12 +00:00
skra
833dcace9c (1) Add a new bus method to get a mapping data for an interrupt.
BUS_MAP_INTR() is used to get an interrupt mapping data according
to provided hints. The hints could be modified afterwards, but only
if mapping data was allocated. This method is intended to be called
before BUS_ALLOC_RESOURCE().

An interrupt mapping data describes an interrupt - hardware number,
type, configuration, cpu binding, and whatever is needed to setup it.

(2) Introduce a method which allows storing of an additional data
in struct resource to be available for bus drivers. This method is
convenient in two ways:
 - there is no need to rework existing bus drivers as they can simply
   be extended to provide an additional data,
 - there is no need to modify any existing bus methods as struct
   resource is already passed to them as argument and thus stored data
   is simply accessible by other bus drivers.
For now, implement this method only for INTRNG.

This is motivated by needs of modern SOCs where hardware initialization
is not straightforward and resources descriptions are complex, opaque
for everyone but provider, and may vary from SOC to SOC. Typical
situation is that one bus driver can fetch a resource description for
its child device, but it's opaque for this driver. Another bus driver
knows a provider for this kind of resource and can pass this resource
description to it. In fact, something like device IVARS would be
perfect for that if implemented generally enough. Unfortunatelly, IVARS
are usable only by their owners now. Only owner knows its IVARS layout,
thus other bus drivers are not able to use them.

Differential Revision:	https://reviews.freebsd.org/D6632
2016-06-05 16:07:57 +00:00