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Initial splitoff of the low-level stuff; taken to fdtable.h
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* Use new set_cpus_allowed_ptr() function added by previous patch,
which instead of passing the "newly allowed cpus" cpumask_t arg
by value, pass it by pointer:
-int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
+int set_cpus_allowed_ptr(struct task_struct *p, const cpumask_t *new_mask)
* Modify CPU_MASK_ALL
Depends on:
[sched-devel]: sched: add new set_cpus_allowed_ptr function
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This test seems to be unnecessary since we always have rootfs mounted before
calling a usermodehelper.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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call_usermodehelper_exec() has an exit path that can leave the
helper_lock() call at the top of the routine unbalanced. The attached
patch fixes this issue.
Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The semantics of call_usermodehelper_pipe() used to be that it would fork
the helper, and wait for the kernel thread to be started. This was
implemented by setting sub_info.wait to 0 (implicitly), and doing a
wait_for_completion().
As part of the cleanup done in 0ab4dc92278a0f3816e486d6350c6652a72e06c8,
call_usermodehelper_pipe() was changed to pass 1 as the value for wait to
call_usermodehelper_exec().
This is equivalent to setting sub_info.wait to 1, which is a change from
the previous behaviour. Using 1 instead of 0 causes
__call_usermodehelper() to start the kernel thread running
wait_for_helper(), rather than directly calling ____call_usermodehelper().
The end result is that the calling kernel code blocks until the user mode
helper finishes. As the helper is expecting input on stdin, and now no one
is writing anything, everything locks up (observed in do_coredump).
The fix is to change the 1 to UMH_WAIT_EXEC (aka 0), indicating that we
want to wait for the kernel thread to be started, but not for the helper to
finish.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix kmod.c:
Warning(linux-2.6.23-rc1//kernel/kmod.c:364): No description found for parameter 'envp'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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At present, if a user mode helper is running while
usermodehelper_pm_callback() is executed, the helper may be frozen and the
completion in call_usermodehelper_exec() won't be completed until user
space processes are thawed. As a result, the freezing of kernel threads
may fail, which is not desirable.
Prevent this from happening by introducing a counter of running user mode
helpers and allowing usermodehelper_pm_callback() to succeed for action =
PM_HIBERNATION_PREPARE or action = PM_SUSPEND_PREPARE only if there are no
helpers running. [Namely, usermodehelper_pm_callback() waits for at most
RUNNING_HELPERS_TIMEOUT for the number of running helpers to become zero
and fails if that doesn't happen.]
Special thanks to Uli Luckas <u.luckas@road.de>, Pavel Machek
<pavel@ucw.cz> and Oleg Nesterov <oleg@tv-sign.ru> for reviewing the
previous versions of this patch and for very useful comments.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Uli Luckas <u.luckas@road.de>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Use a hibernation and suspend notifier to disable the user mode helper before
a hibernation/suspend and enable it after the operation.
[akpm@linux-foundation.org: build fix]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Rather than using a tri-state integer for the wait flag in
call_usermodehelper_exec, define a proper enum, and use that. I've
preserved the integer values so that any callers I've missed should
still work OK.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: David Howells <dhowells@redhat.com>
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Rather than having hundreds of variations of call_usermodehelper for
various pieces of usermode state which could be set up, split the
info allocation and initialization from the actual process execution.
This means the general pattern becomes:
info = call_usermodehelper_setup(path, argv, envp); /* basic state */
call_usermodehelper_<SET EXTRA STATE>(info, stuff...); /* extra state */
call_usermodehelper_exec(info, wait); /* run process and free info */
This patch introduces wrappers for all the existing calling styles for
call_usermodehelper_*, but folds their implementations into one.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Bj?rn Steinbrink <B.Steinbrink@gmx.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
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allow_signal(SIGCHLD) does all necessary job, no need to call do_sigaction()
prior to.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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____call_usermodehelper() has no reason for flush_signals(). It is a fresh
forked process which is going to exec a user-space application or exit on
failure.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix kevent's childs priority greediness. Such tasks were always scheduled
at nice level -5 and, at that time, udev stole us the CPU time with -5.
Already posted at http://lkml.org/lkml/2005/1/10/85
[akpm@linux-foundation.org: add comment]
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.
Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This reverts commit c353c3fb0700a3c17ea2b0237710a184232ccd7f.
It turns out that we end up with a loop trying to load the unix
module and calling netfilter to do that. Will redo the patch
later to not have this loop.
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This patch makes the needlessly global struct kmod_mk static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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On recent systems, calls to /sbin/modprobe are handled by udev depending
on the kind of device the kernel has discovered. This patch creates an
uevent for the kernels internal request_module(), to let udev take control
over the request, instead of forking the binary directly by the kernel.
The direct execution of /sbin/modprobe can be disabled by setting:
/sys/module/kmod/mod_request_helper (/proc/sys/kernel/modprobe)
to an empty string, the same way /proc/sys/kernel/hotplug is disabled on an
udev system.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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When a machine check event is detected (including a AMD RevF threshold
overflow event) allow to run a "trigger" program. This allows user space
to react to such events sooner.
The trigger is configured using a new trigger entry in the
machinecheck sysfs interface. It is currently shared between
all CPUs.
I also fixed the AMD threshold handler to run the machine
check polling code immediately to actually log any events
that might have caused the threshold interrupt.
Also added some documentation for the mce sysfs interface.
Signed-off-by: Andi Kleen <ak@suse.de>
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Rename 'struct namespace' to 'struct mnt_namespace' to avoid confusion with
other namespaces being developped for the containers : pid, uts, ipc, etc.
'namespace' variables and attributes are also renamed to 'mnt_ns'
Signed-off-by: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
drivers/infiniband/core/iwcm.c
drivers/net/chelsio/cxgb2.c
drivers/net/wireless/bcm43xx/bcm43xx_main.c
drivers/net/wireless/prism54/islpci_eth.c
drivers/usb/core/hub.h
drivers/usb/input/hid-core.c
net/core/netpoll.c
Fix up merge failures with Linus's head and fix new compilation failures.
Signed-Off-By: David Howells <dhowells@redhat.com>
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The return value of create_write_pipe()/create_read_pipe() should be
checked by IS_ERR().
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Pass the work_struct pointer to the work function rather than context data.
The work function can use container_of() to work out the data.
For the cases where the container of the work_struct may go away the moment the
pending bit is cleared, it is made possible to defer the release of the
structure by deferring the clearing of the pending bit.
To make this work, an extra flag is introduced into the management side of the
work_struct. This governs auto-release of the structure upon execution.
Ordinarily, the work queue executor would release the work_struct for further
scheduling or deallocation by clearing the pending bit prior to jumping to the
work function. This means that, unless the driver makes some guarantee itself
that the work_struct won't go away, the work function may not access anything
else in the work_struct or its container lest they be deallocated.. This is a
problem if the auxiliary data is taken away (as done by the last patch).
However, if the pending bit is *not* cleared before jumping to the work
function, then the work function *may* access the work_struct and its container
with no problems. But then the work function must itself release the
work_struct by calling work_release().
In most cases, automatic release is fine, so this is the default. Special
initiators exist for the non-auto-release case (ending in _NAR).
Signed-Off-By: David Howells <dhowells@redhat.com>
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The use of execve() in the kernel is dubious, since it relies on the
__KERNEL_SYSCALLS__ mechanism that stores the result in a global errno
variable. As a first step of getting rid of this, change all users to a
global kernel_execve function that returns a proper error code.
This function is a terrible hack, and a later patch removes it again after the
kernel syscalls are gone.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Hirokazu Takata <takata.hirokazu@renesas.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Using the infrastructure created in previous patches implement support to
pipe core dumps into programs.
This is done by overloading the existing core_pattern sysctl
with a new syntax:
|program
When the first character of the pattern is a '|' the kernel will instead
threat the rest of the pattern as a command to run. The core dump will be
written to the standard input of that program instead of to a file.
This is useful for having automatic core dump analysis without filling up
disks. The program can do some simple analysis and save only a summary of
the core dump.
The core dump proces will run with the privileges and in the name space of
the process that caused the core dump.
I also increased the core pattern size to 128 bytes so that longer command
lines fit.
Most of the changes comes from allowing core dumps without seeks. They are
fairly straight forward though.
One small incompatibility is that if someone had a core pattern previously
that started with '|' they will get suddenly new behaviour. I think that's
unlikely to be a real problem though.
Additional background:
> Very nice, do you happen to have a program that can accept this kind of
> input for crash dumps? I'm guessing that the embedded people will
> really want this functionality.
I had a cheesy demo/prototype. Basically it wrote the dump to a file again,
ran gdb on it to get a backtrace and wrote the summary to a shared directory.
Then there was a simple CGI script to generate a "top 10" crashes HTML
listing.
Unfortunately this still had the disadvantage to needing full disk space for a
dump except for deleting it afterwards (in fact it was worse because over the
pipe holes didn't work so if you have a holey address map it would require
more space).
Fortunately gdb seems to be happy to handle /proc/pid/fd/xxx input pipes as
cores (at least it worked with zsh's =(cat core) syntax), so it would be
likely possible to do it without temporary space with a simple wrapper that
calls it in the right way. I ran out of time before doing that though.
The demo prototype scripts weren't very good. If there is really interest I
can dig them out (they are currently on a laptop disk on the desk with the
laptop itself being in service), but I would recommend to rewrite them for any
serious application of this and fix the disk space problem.
Also to be really useful it should probably find a way to automatically fetch
the debuginfos (I cheated and just installed them in advance). If nobody else
does it I can probably do the rewrite myself again at some point.
My hope at some point was that desktops would support it in their builtin
crash reporters, but at least the KDE people I talked too seemed to be happy
with their user space only solution.
Alan sayeth:
I don't believe that piping as such as neccessarily the right model, but
the ability to intercept and processes core dumps from user space is asked
for by many enterprise users as well. They want to know about, capture,
analyse and process core dumps, often centrally and in automated form.
[akpm@osdl.org: loff_t != unsigned long]
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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A new member in the ever growing family of call_usermode* functions is
born. The new call_usermodehelper_pipe() function allows to pipe data to
the stdin of the called user mode progam and behaves otherwise like the
normal call_usermodehelp() (except that it always waits for the child to
finish)
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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If ____call_usermodehelper fails, we're not interested in the child
process' exit value, but the real error, so let's stop wait_for_helper from
overwriting it in that case.
Issue discovered by Benedikt Böhm while working on a Linux-VServer usermode
helper.
Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I think there is a bug in kmod.c: In __call_usermodehelper(), when
kernel_thread(wait_for_helper, ...) return success, since wait_for_helper()
might call complete() at any time, the sub_info should not be used any
more.
Normally wait_for_helper() take a long time to finish, you may not get
problem for most of the case. But if you remove /sbin/modprobe, it may
become easier for you to get a oop in khelper.
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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lockdep needs to have the waitqueue lock initialized for on-stack waitqueues
implicitly initialized by DECLARE_COMPLETION(). Annotate on-stack completions
accordingly.
Has no effect on non-lockdep kernels.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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Use NULL instead of (... *)0
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The attached patch gets rid of a "statement without effect" warning when
CONFIG_KEYS is disabled by making use of the return value of key_get().
The compiler will optimise all of this away when keys are disabled.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The attached patch makes it possible to pass a session keyring through to the
process spawned by call_usermodehelper(). This allows patch 3/3 to pass an
authorisation key through to /sbin/request-key, thus permitting better access
controls when doing just-in-time key creation.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Move hotplug_path[] out of kmod.[ch] to kobject_uevent.[ch] where
it belongs now. At some time in the future we should fix the remaining bad
hotplug calls (no SEQNUM, no netlink uevent):
./drivers/input/input.c (no DEVPATH on some hotplug events!)
./drivers/pnp/pnpbios/core.c
./drivers/s390/crypto/z90main.c
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
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Currently most driver events are not sent out when using initramfs as
driver_init() (which triggers the events) is called before init_workqueues.
This patch rearranges the init calls so that the hotplug event queue is
enabled prior to calling driver_init(), hence we're getting all hotplug
events again.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Rusty Russell <rusty@rustcorp.com.au>
Paul Jackson's cpumask tour-de-force allows us to get rid of those stupid
temporaries which we used to hold CPU_MASK_ALL to hand them to functions.
This used to break NR_CPUS > BITS_PER_LONG.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Andy Whitcroft <apw@shadowen.org>
Both modprobe_path and hotplug_path are arbitrarily sized at 256 bytes and
that size is also expressed directly in the sysctl code. It seems
reasonable to define a standard length and use that for consitancy. This
patch introduces the constant KMOD_PATH_LEN and uses that.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Big comment, because it wasn't clear why this cast was valid.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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We may as well make usermodehelper_init() core_initcall as well, to make
sure its services are avaialble to all the other initcall levels.
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From: Rusty Russell <rusty@rustcorp.com.au>
call_usermodehelper uses keventd to create a thread, guaranteeing a nice,
clean kernel thread. Unfortunately, there is a case where
call_usermodehelper is called with &bus->subsys.rwsem held (via
bus_add_driver()), but keventd could be running bus_add_device(), which is
blocked on the same lock. The result is deadlock, and it comes from using
keventd for both.
In this case, it can be fixed by using a completely independent thread for
call_usermodehelper, or an independent workqueue. Workqueues have the
infrastructure we need, so we use one.
Move EXPORT_SYMBOL while we're there, too.
akpm fixes: Make it compile with !CONFIG_KMOD
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From: Olof Johansson <olof@austin.ibm.com>
It's currently a boolean, but that means that system_running goes to zero
again when shutting down. So we then use code (in the page allocator) which
is only designed to be used during bootup - it is marked __init.
So we need to be able to distinguish early boot state from late shutdown
state. Rename system_running to system_state and give it the three
appropriate states.
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From: "Randy.Dunlap" <rddunlap@osdl.org>
Add syscalls.h, which contains prototypes for the kernel's system calls.
Replace open-coded declarations all over the place. This patch found a
couple of prior bugs. It appears to be more important with -mregparm=3 as we
discover more asmlinkage mismatches.
Some syscalls have arch-dependent arguments, so their prototypes are in the
arch-specific unistd.h. Maybe it should have been asm/syscalls.h, but there
were already arch-specific syscall prototypes in asm/unistd.h...
Tested on x86, ia64, x86_64, ppc64, s390 and sparc64. May cause
trivial-to-fix build breakage on other architectures.
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From: Rusty Russell <rusty@rustcorp.com.au>
These two patches provide the framework for stopping kernel threads to
allow hotplug CPU. This one just adds kthread.c and kthread.h, next
one uses it.
Most importantly, adds a Monty Python quote to the kernel.
Details:
The hotplug CPU code introduces two major problems:
1) Threads which previously never stopped (migration thread,
ksoftirqd, keventd) have to be stopped cleanly as CPUs go offline.
2) Threads which previously never had to be created now have
to be created when a CPU goes online.
Unfortunately, stopping a thread is fairly baroque, involving memory
barriers, a completion and spinning until the task is actually dead
(for example, complete_and_exit() must be used if inside a module).
There are also three problems in starting a thread:
1) Doing it from a random process context risks environment contamination:
better to do it from keventd to guarantee a clean environment, a-la
call_usermodehelper.
2) Getting the task struct without races is a hard: see kernel/sched.c
migration_call(), kernel/workqueue.c create_workqueue_thread().
3) There are races in starting a thread for a CPU which is not yet
online: migration thread does a complex dance at the moment for
a similar reason (there may be no migration thread to migrate us).
Place all this logic in some primitives to make life easier:
kthread_create() and kthread_stop(). These primitives require no
extra data-structures in the caller: they operate on normal "struct
task_struct"s.
Other changes:
- Expose keventd_up(), as keventd and migration threads will use kthread to
launch, and kthread normally uses workqueues and must recognize this case.
- Kthreads created at boot before "keventd" are spawned directly. However,
this means that they don't have all signals blocked, and hence can be
killed. The simplest solution is to always explicitly block all signals in
the kthread.
- Change over the migration threads, the workqueue threads and the
ksoftirqd threads to use kthread.
- module.c currently spawns threads directly to stop the machine, so a
module can be atomically tested for removal.
- Unfortunately, this means that the current task is manipulated (which
races with set_cpus_allowed, for example), and it can't set its priority
artificially high. Using a kernel thread can solve this cleanly, and with
kthread_run, it's simple.
- kthreads use keventd, so they inherit its cpus_allowed mask. Unset it.
All current users set it explicity anyway, but it's nice to fix.
- call_usermode_helper uses keventd, so the process created inherits its
cpus_allowed mask. Unset it.
- Prevent errors in boot when cpus_possible() contains a cpu which is not
online (ie. a cpu didn't come up). This doesn't happen on x86, since a
boot failure makes that CPU no longer possible (hacky, but it works).
- When the cpu fails to come up, some callbacks do kthread_stop(), which
doesn't work without keventd (which hasn't started yet). Call it directly,
and take care that it restores signal state (note: do_sigaction does a
flush on blocked signals, so we don't need to repeat it).
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In almost all distributions, the kernel asks for modules which don't
exist, such as "net-pf-10" or whatever. Changing "modprobe -q" to
"succeed" in this case is hacky and breaks some setups, and also we
want to know if it failed for the fallback code for old aliases in
fs/char_dev.c, for example.
Just remove the debugging message which fill people's logs: the
correct way of debugging module problems is something like this:
echo '#! /bin/sh' > /tmp/modprobe
echo 'echo "$@" >> /tmp/modprobe.log' >> /tmp/modprobe
echo 'exec /sbin/modprobe "$@"' >> /tmp/modprobe
chmod a+x /tmp/modprobe
echo /tmp/modprobe > /proc/sys/kernel/modprobe
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The reworked firmware loader in the DVB patches needs the fix to the
call_usermodehelper() return value.
From: Rusty Russell <rusty@rustcorp.com.au>
MODULE_ALIAS_BLOCK() and MODULE_ALIAS_CHAR() define aliases of form
"XXX-<major>-<minor>", so we should probe for modules using this form.
Unfortunately in 2.4, block aliases were "XXX-<major>" and char aliases
were of both forms.
Ideally, all modules would now be using MODULE_ALIAS() macros to define
their aliases, and the old configuration files wouldn't matter as much.
Unfortunately, this hasn't happened, so we make request_module() return the
exit status of modprobe, and then do fallback when probing for char and
block devices.
(Kudos to Chris Wright, I stole his kernel_thread flags).
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There seems to be no header file which declares system_running.
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From: Michael Still <mikal@stillhq.com>
The patch squelches build errors in the kernel-doc make targets by adding
documentation to arguements previously not documented, and updating the
argument names where they have changed.
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The kernel invokes "modprobe" on modules which might not exist:
rightfully, modprobe complains by default when this happens. So the
correct response is to invoke "modprobe -q", which is silent on such
errors (but still reports other errors such as config errors).
Also, use MODULE_NAME_LEN from module.h instead of inventing our own.
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From: Rusty Russell <rusty@rustcorp.com.au>
Milton Miller <miltonm@bga.com> and Junfeng Yang <yjf@stanford.edu> point
out that we hand a kernel address to sys_wait4 for the status pointer.
This is true, but since we don't have a SIGCHLD handler, it never gets that
far. Use NULL, and document the fact.
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The location between the comment and the prototype confused kernel-doc.
Kernel-doc requires the prototype to follow after the comment section.
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We had two major issues when unregistering networking devices.
1) Even trying to run hotplug asynchronously could deadlock
if keventd was currently trying to get the RTNL semaphore
in order to process linkwatch events.
2) Unregister needs to wait for the last reference to go away
before the finalization of the unregister can execute. This
cannot occur under the RTNL semaphore as this is deadlock
prone as well.
The solution is to do all of this stuff after dropping the
RTNL semaphore. rtnl_lock, if it is about to protect a region
of code that could unregister network devices, registers a list
to which unregistered netdevs are attached. At rtnl_unlock time
this list is processed to wait for refcounts to drop to zero and
then finalize the unregister.
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