weak aliases device_register(9) and device_register_post_config(9)
for the stub routine voidop(). Get rid of __HAVE_DEVICE_REGISTER and
__HAVE_DEVICE_REGISTER_POST_CONFIG.
after mountroot(), like config_interrupt(9) that defers
configuration after interrupts are enabled.
This will be used for devices that require firmware loaded
from the root file system by firmload(9) to complete device
initialization (getting MAC address etc).
No objection on tech-kern@:
http://mail-index.NetBSD.org/tech-kern/2010/06/18/msg008370.html
and will also fix PR kern/43125.
and acquiring alldevs_mtx already blocks those interrupts, so delete the
splhigh()/splx() in config_alldevs_lock()/_unlock().
Release alldevs_mtx while freeing memory with kmem_free(9); according to
new documentation, kmem_free(9) can sleep! :-) Thanks to rmind@ for the
tip.
Next step: use finer-grained locking, probably by adding a mutex to
cfdriver_t.
And after that: make sure that all threads of execution are out of the
device_t and/or softc before releasing their memory.
driver/attach/data typically present and once some locking is grown
in here, these routines can be made to fail or succeed a component
attachment/detachment atomically.
and non-const types, and the kernel uses both const and non-const
PMF qualifiers and device suspensors, so change the pmf_qual_t and
device_suspensor_t typedefs from "pointers to const" to non-pointer,
non-const types.
out of the way before trying to get a unit number. If we cannot
get a unit number, we call config_devfree(), which expects for
fields such as dv_flags, dv_cfattach, and dv_private to be initialized.
into subr_device.c instead of having them in subr_autoconf.c.
Since none of the copyrights in subr_autoconf.c really match the
history of device accessors, I took the liberty of slapping (c)
2006 TNF onto subr_device.c.
priority level where the kernel accesses alldevs is IPL_VM, where
some hardware interrupt handlers call config_deactivate(9). Lower
the IPL of alldevs_mtx from IPL_HIGH to IPL_VM, accordingly.
subroutines config_alldevs_enter() and config_alldevs_exit(). This
change amounts to textual substitution. No functional change intended.
We do not collect garbage in device_lookup(), so there is no use dumping
it: get rid of the garbage list. Do not call config_dump_garbage().
In device_lookup_private(), call device_lookup() instead of duplicating
the code from device_lookup().
duplicating code.
Per suggestions by rmind@:
Simplify some code that used "empty statements," ";".
Don't collect garbage in device_lookup{,_private}(), since they
are called in interrupt context from certain drivers.
Make config_collect_garbage() KASSERT() that it does not run in
interrupt or software-interrupt context.
collecting garbage in two phases: in the first stage, with
alldevs_mtx held, gather all of the objects to be freed onto a
list. Drop alldevs_mtx, and in the second stage, free all the
collected objects.
Also per rmind@'s suggestion, remove KASSERT(!mutex_owned(&alldevs_mtx))
throughout, it is not useful.
Find a free unit number and allocate it for a new device_t atomically.
Before, two threads would sometimes find the same free unit number
and race to allocate it. The loser panicked. Now there is no
race.
In support of the changes above, extract some new subroutines that
are private to this module: config_unit_nextfree(), config_unit_alloc(),
config_devfree(), config_dump_garbage().
Delete all of the #ifdef __BROKEN_CONFIG_UNIT_USAGE code. Only
the sun3 port still depends on __BROKEN_CONFIG_UNIT_USAGE, it's
not hard for the port to do without, and port-sun3@ had fair warning
that it was going away (>1 week, or a few years' warning, depending
how far back you look!).
I applied this patch with Coccinelle's semantic patch tool, spatch(1).
I installed Coccinelle from pkgsrc: devel/coccinelle/. I wrote
tailq.spatch and kdefs.h (see below) and ran this command,
spatch -debug -macro_file_builtins ./kdefs.h -outplace \
-sp_file sys/kern/tailq.spatch sys/kern/subr_autoconf.c
which wrote the transformed source file to /tmp/subr_autoconf.c. Then I
used indent(1) to fix the indentation.
::::::::::::::::::::
::: tailq.spatch :::
::::::::::::::::::::
@@
identifier I, N;
expression H;
statement S;
iterator name TAILQ_FOREACH;
@@
- for (I = TAILQ_FIRST(H); I != NULL; I = TAILQ_NEXT(I, N)) S
+ TAILQ_FOREACH(I, H, N) S
:::::::::::::::
::: kdefs.h :::
:::::::::::::::
#define MAXUSERS 64
#define _KERNEL
#define _KERNEL_OPT
#define i386
/*
* Tail queue definitions.
*/
#define _TAILQ_HEAD(name, type, qual) \
struct name { \
qual type *tqh_first; /* first element */ \
qual type *qual *tqh_last; /* addr of last next element */ \
}
#define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type,)
#define TAILQ_HEAD_INITIALIZER(head) \
{ NULL, &(head).tqh_first }
#define _TAILQ_ENTRY(type, qual) \
struct { \
qual type *tqe_next; /* next element */ \
qual type *qual *tqe_prev; /* address of previous next element */\
}
#define TAILQ_ENTRY(type) _TAILQ_ENTRY(struct type,)
#define PMF_FN_PROTO1 pmf_qual_t
#define PMF_FN_ARGS1 pmf_qual_t qual
#define PMF_FN_CALL1 qual
#define PMF_FN_PROTO , pmf_qual_t
#define PMF_FN_ARGS , pmf_qual_t qual
#define PMF_FN_CALL , qual
#define __KERNEL_RCSID(a, b)
the system into config_deactivate(dev): deactivate dev and all of
its descendants. Block all interrupts while calling each device's
activation hook, ca_activate. Now it is possible to simplify or
to delete several device-activation hooks throughout the system.
Do not deactivate a driver while detaching it! If the driver was
already deactivated (because of accidental/emergency removal), let
the driver cope with the knowledge that DVF_ACTIVE has been cleared.
Otherwise, let the driver access the underlying hardware (so that
it can flush caches, restore original register settings, et cetera)
until it exits its device-detachment hook.
Let multiple readers and writers simultaneously access the system's
device_t list, alldevs, from either interrupt or thread context:
postpone changing alldevs linkages and freeing autoconf device
structures until a garbage-collection phase that runs after all
readers & writers have left the list.
Give device iterators (deviter(9)) a consistent view of alldevs no
matter whether device_t's are added and deleted during iteration:
keep a global alldevs generation number. When an iterator enters
alldevs, record the current generation number in the iterator and
increase the global number. When a device_t is created, label it
with the current global generation number. When a device_t is
deleted, add a second label, the current global generation number.
During iteration, compare a device_t's added- and deleted-generation
with the iterator's generation and skip a device_t that was deleted
before the iterator entered the list or added after the iterator
entered the list.
The alldevs generation number is never 0. The garbage collector
reaps device_t's whose delete-generation number is non-zero.
Make alldevs private to sys/kern/subr_autoconf.c. Use deviter(9)
to access it.
and make suspension by self, by drvctl(8), and by ACPI system sleep
play nice together. Start solidifying some temporary API changes.
1. Extract a new header file, <sys/device_if.h>, from <sys/device.h> and
#include it from <sys/pmf.h> instead of <sys/device.h> to break the
circular dependency between <sys/device.h> and <sys/pmf.h>.
2. Introduce pmf_qual_t, an aggregate of qualifications on a PMF
suspend/resume call. Start to replace instances of PMF_FN_PROTO,
PMF_FN_ARGS, et cetera, with a pmf_qual_t.
3. Introduce the notion of a "suspensor," an entity that holds a
device in suspension. More than one suspensor may hold a device
at once. A device stays suspended as long as at least one
suspensor holds it. A device resumes when the last suspensor
releases it.
Currently, the kernel defines three suspensors,
3a the system-suspensor: for system suspension, initiated
by 'sysctl -w machdep.sleep_state=3', by lid closure, by
power-button press, et cetera,
3b the drvctl-suspensor: for device suspension by /dev/drvctl
ioctl, e.g., drvctl -S sip0.
3c the system self-suspensor: for device drivers that suspend
themselves and their children. Several drivers for network
interfaces put the network device to sleep while it is not
administratively up, that is, after the kernel calls if_stop(,
1). The self-suspensor should not be used directly. See
the description of suspensor delegates, below.
A suspensor can have one or more "delegates". A suspensor can
release devices that its delegates hold suspended. Right now,
only the system self-suspensor has delegates. For each device
that a self-suspending driver attaches, it creates the device's
self-suspensor, a delegate of the system self-suspensor.
Suspensors stop a system-wide suspend/resume cycle from waking
devices that the operator put to sleep with drvctl before the cycle.
They also help self-suspension to work more simply, safely, and in
accord with expectations.
4. Add the notion of device activation level, devact_level_t,
and a routine for checking the current activation level,
device_activation(). Current activation levels are DEVACT_LEVEL_BUS,
DEVACT_LEVEL_DRIVER, and DEVACT_LEVEL_CLASS, which respectively
indicate that the device's bus is active, that the bus and device are
active, and that the bus, device, and the functions of the device's
class (network, audio) are active.
Suspend/resume calls can be qualified with a devact_level_t.
The power-management framework treats a devact_level_t that
qualifies a device suspension as the device's current activation
level; it only runs hooks to reduce the activation level from
the presumed current level to the fully suspended state. The
framework treats a devact_level_t qualifying device resumption
as the target activation level; it only runs hooks to raise the
activation level to the target.
5. Use pmf_qual_t, devact_level_t, and self-suspensors in several
drivers.
6. Temporarily add an unused power-management workqueue that I will
remove or replace, soon.
since they are only peripherially related to the autoconf subsystem
and more related to boot initialization. Also, apply _KERNEL_OPT
to autoconf where necessary.
(void *)pew is one way to get a struct work *, but let's
write&pew->pew_work, instead. It is more defensive and persuasive.
Make miscellaneous changes in support of tearing down arbitrary
stacks of filesystems and devices during shutdown:
1 Move struct shutdown_state, shutdown_first(), and shutdown_next(),
from kern_pmf.c to subr_autoconf.c. Rename detach_all() to
config_detach_all(), and move it from kern_pmf.c to subr_autoconf.c.
Export all of those routines.
2 In pmf_system_shutdown(), do not suspend user process scheduling, and
do not detach all devices: I am going to do that in cpu_reboot(),
instead. (Soon I will do it in an MI cpu_reboot() routine.) Do still
call PMF shutdown hooks.
3 In config_detach(), add a DIAGNOSTIC assertion: if we're exiting
config_detach() at the bottom, alldevs_nwrite had better not be 0,
because config_detach() is a writer of the device list.
4 In deviter_release(), check to see if we're iterating the device list
for reading, *first*, and if so, decrease the number of readers. Used
to be that if we happened to be reading during shutdown, we ran the
shutdown branch. Thus the number of writers reached 0, the number
of readers remained > 0, and no writer could iterate again. Under
certain circumstances that would cause a hang during shutdown.
