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  1. 21 Oct, 2008 12 commits
    • Heiko Carstens's avatar
      stop_machine: fix error code handling on multiple cpus · 8163bcac
      Heiko Carstens authored 
      Using |= for updating a value which might be updated on several cpus
concurrently will not always work since we need to make sure that the
update happens atomically.
To fix this just use a write if the called function returns an error
code on a cpu. We end up writing the error code of an arbitrary cpu
if multiple ones fail but that should be sufficient.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      8163bcac
    • Heiko Carstens's avatar
      stop_machine: use workqueues instead of kernel threads · c9583e55
      Heiko Carstens authored 
      Convert stop_machine to a workqueue based approach. Instead of using kernel
threads for stop_machine we now use a an rt workqueue to synchronize all
cpus.
This has the advantage that all needed per cpu threads are already created
when stop_machine gets called. And therefore a call to stop_machine won't
fail anymore. This is needed for s390 which needs a mechanism to synchronize
all cpus without allocating any memory.
As Rusty pointed out free_module() needs a non-failing stop_machine interface
as well.

As a side effect the stop_machine code gets simplified.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      c9583e55
    • Heiko Carstens's avatar
      workqueue: introduce create_rt_workqueue · 0d557dc9
      Heiko Carstens authored 
      create_rt_workqueue will create a real time prioritized workqueue.
This is needed for the conversion of stop_machine to a workqueue based
implementation.
This patch adds yet another parameter to __create_workqueue_key to tell
it that we want an rt workqueue.
However it looks like we rather should have something like "int type"
instead of singlethread, freezable and rt.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
      0d557dc9
    • Heiko Carstens's avatar
      Call init_workqueues before pre smp initcalls. · a802dd0e
      Heiko Carstens authored 
      This allows to create workqueues from within the context of
a pre smp initcall (aka early_initcall).
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      a802dd0e
    • Rusty Russell's avatar
      Make panic= and panic_on_oops into core_params · f44dd164
      Rusty Russell authored 
      This allows them to be examined and set after boot, plus means they
actually give errors if they are misused (eg. panic=yes).
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      f44dd164
    • Rusty Russell's avatar
      Make initcall_debug a core_param · d0ea3d7d
      Rusty Russell authored 
      This is the one I really wanted: now it effects module loading, it
makes sense to be able to flip it after boot.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
      d0ea3d7d
    • Rusty Russell's avatar
      core_param() for genuinely core kernel parameters · 67e67cea
      Rusty Russell authored 
      There are a lot of one-liner uses of __setup() in the kernel: they're
cumbersome and not queryable (definitely not settable) via /sys.  Yet
it's ugly to simplify them to module_param(), because by default that
inserts a prefix of the module name (usually filename).

So, introduce a "core_param".  The parameter gets no prefix, but
appears in /sys/module/kernel/parameters/ (if non-zero perms arg).  I
thought about using the name "core", but that's more common than
"kernel".  And if you create a module called "kernel", you will die
a horrible death.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      67e67cea
    • Rusty Russell's avatar
      param: Fix duplicate module prefixes · 9b473de8
      Rusty Russell authored 
      Instead of insisting each new module_param sysfs entry is unique,
handle the case where it already exists (for builtin modules).

The current code assumes that all identical prefixes are together in
the section: true for normal uses, but not necessarily so if someone
overrides MODULE_PARAM_PREFIX.  More importantly, it's not true with
the new "core_param()" code which uses "kernel" as a prefix.

This simplifies the caller for the builtin case, at a slight loss of
efficiency (we do the lookup every time to see if the directory
exists).
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
      9b473de8
    • Rusty Russell's avatar
      module: check kernel param length at compile time, not runtime · 730b69d2
      Rusty Russell authored 
      The kparam code tries to handle over-length parameter prefixes at
runtime.  Not only would I bet this has never been tested, it's not
clear that truncating names is a good idea either.

So let's check at compile time.  We need to move the #define to
moduleparam.h to do this, though.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      730b69d2
    • Andi Kleen's avatar
      Remove stop_machine during module load v2 · d72b3751
      Andi Kleen authored 
      Remove stop_machine during module load v2

module loading currently does a stop_machine on each module load to insert
the module into the global module lists.  Especially on larger systems this
can be quite expensive.

It does that to handle concurrent lock lessmodule list readers
like kallsyms.

I don't think stop_machine() is actually needed to insert something
into a list though. There are no concurrent writers because the
module mutex is taken. And the RCU list functions know how to insert
a node into a list with the right memory ordering so that concurrent
readers don't go off into the wood.

So remove the stop_machine for the module list insert and just
do a list_add_rcu() instead.

Module removal will still do a stop_machine of course, it needs
that for other reasons.

v2: Revised readers based on Paul's comments. All readers that only
    rely on disabled preemption need to be changed to list_for_each_rcu().
    Done that. The others are ok because they have the modules mutex.
    Also added a possible missing preempt disable for print_modules().

[cc Paul McKenney for review. It's not RCU, but quite similar.]
Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      d72b3751
    • Rusty Russell's avatar
      module: simplify load_module. · 5e458cc0
      Rusty Russell authored 
      Linus' recent catch of stack overflow in load_module lead me to look
at the code.  A couple of helpers to get a section address and get
objects from a section can help clean things up a little.

(And in case you're wondering, the stack size also dropped from 328 to
284 bytes).
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      5e458cc0
    • Paul Mundt's avatar
      binfmt_elf_fdpic: Update for cputime changes. · 2515ddc6
      Paul Mundt authored 
      Commit f06febc9 ("timers: fix itimer/
many thread hang") introduced a new task_cputime interface and
subsequently only converted binfmt_elf over to it.  This results in the
build for binfmt_elf_fdpic blowing up given that p->signal->{u,s}time
have disappeared from underneath us.

Apply the same trivial fix from binfmt_elf to binfmt_elf_fdpic.
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2515ddc6
  3. 20 Oct, 2008 28 commits