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  1. 22 10月, 2008 10 次提交
    • H
      stop_machine: use workqueues instead of kernel threads · c9583e55
      由 Heiko Carstens 提交于 
      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: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      c9583e55
    • H
      workqueue: introduce create_rt_workqueue · 0d557dc9
      由 Heiko Carstens 提交于 
      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: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
      0d557dc9
    • H
      Call init_workqueues before pre smp initcalls. · a802dd0e
      由 Heiko Carstens 提交于 
      This allows to create workqueues from within the context of
a pre smp initcall (aka early_initcall).
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      a802dd0e
    • R
      Make panic= and panic_on_oops into core_params · f44dd164
      由 Rusty Russell 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
      f44dd164
    • R
      Make initcall_debug a core_param · d0ea3d7d
      由 Rusty Russell 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
      d0ea3d7d
    • R
      core_param() for genuinely core kernel parameters · 67e67cea
      由 Rusty Russell 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
      67e67cea
    • R
      param: Fix duplicate module prefixes · 9b473de8
      由 Rusty Russell 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
      9b473de8
    • R
      module: check kernel param length at compile time, not runtime · 730b69d2
      由 Rusty Russell 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
      730b69d2
    • A
      Remove stop_machine during module load v2 · d72b3751
      由 Andi Kleen 提交于 
      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: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      d72b3751
    • R
      module: simplify load_module. · 5e458cc0
      由 Rusty Russell 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
      5e458cc0
  3. 21 10月, 2008 30 次提交