linux-toradex.git/kernel/sys.c, branch v2.6.35-rc3

kmod: add init function to usermodehelper

2010-05-27T16:12:44+00:00

About 6 months ago, I made a set of changes to how the core-dump-to-a-pipe
feature in the kernel works.  We had reports of several races, including
some reports of apps bypassing our recursion check so that a process that
was forked as part of a core_pattern setup could infinitely crash and
refork until the system crashed.

We fixed those by improving our recursion checks.  The new check basically
refuses to fork a process if its core limit is zero, which works well.

Unfortunately, I've been getting grief from maintainer of user space
programs that are inserted as the forked process of core_pattern.  They
contend that in order for their programs (such as abrt and apport) to
work, all the running processes in a system must have their core limits
set to a non-zero value, to which I say 'yes'.  I did this by design, and
think thats the right way to do things.

But I've been asked to ease this burden on user space enough times that I
thought I would take a look at it.  The first suggestion was to make the
recursion check fail on a non-zero 'special' number, like one.  That way
the core collector process could set its core size ulimit to 1, and enable
the kernel's recursion detection.  This isn't a bad idea on the surface,
but I don't like it since its opt-in, in that if a program like abrt or
apport has a bug and fails to set such a core limit, we're left with a
recursively crashing system again.

So I've come up with this.  What I've done is modify the
call_usermodehelper api such that an extra parameter is added, a function
pointer which will be called by the user helper task, after it forks, but
before it exec's the required process.  This will give the caller the
opportunity to get a call back in the processes context, allowing it to do
whatever it needs to to the process in the kernel prior to exec-ing the
user space code.  In the case of do_coredump, this callback is ues to set
the core ulimit of the helper process to 1.  This elimnates the opt-in
problem that I had above, as it allows the ulimit for core sizes to be set
to the value of 1, which is what the recursion check looks for in
do_coredump.

This patch:

Create new function call_usermodehelper_fns() and allow it to assign both
an init and cleanup function, as we'll as arbitrary data.

The init function is called from the context of the forked process and
allows for customization of the helper process prior to calling exec.  Its
return code gates the continuation of the process, or causes its exit.
Also add an arbitrary data pointer to the subprocess_info struct allowing
for data to be passed from the caller to the new process, and the
subsequent cleanup process

Also, use this patch to cleanup the cleanup function.  It currently takes
an argp and envp pointer for freeing, which is ugly.  Lets instead just
make the subprocess_info structure public, and pass that to the cleanup
and init routines

Signed-off-by: Neil Horman 
Reviewed-by: Oleg Nesterov 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'master' into next

2010-05-06T00:56:07+00:00

kernel/sys.c: fix compat uname machine

2010-04-24T18:31:24+00:00

On ppc64 you get this error:

  $ setarch ppc -R true
  setarch: ppc: Unrecognized architecture

because uname still reports ppc64 as the machine.

So mask off the personality flags when checking for PER_LINUX32.

Signed-off-by: Andreas Schwab 
Reviewed-by: Christoph Hellwig 
Acked-by: David S. Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

security: remove dead hook task_setgid

2010-04-12T02:19:17+00:00

Unused hook.  Remove.

Signed-off-by: Eric Paris 
Signed-off-by: James Morris

security: remove dead hook task_setuid

2010-04-12T02:19:16+00:00

Unused hook.  Remove.

Signed-off-by: Eric Paris 
Signed-off-by: James Morris

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32+00:00

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo 
Guess-its-ok-by: Christoph Lameter 
Cc: Ingo Molnar 
Cc: Lee Schermerhorn

Add generic sys_olduname()

2010-03-12T23:52:32+00:00

Add generic implementations of the old and really old uname system calls.
Note that sh only implements sys_olduname but not sys_oldolduname, but I'm
not going to bother with another ifdef for that special case.

m32r implemented an old uname but never wired it up, so kill it, too.

Signed-off-by: Christoph Hellwig 
Cc: Ralf Baechle 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mundt 
Cc: Jeff Dike 
Cc: Hirokazu Takata 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: H. Peter Anvin 
Cc: Al Viro 
Cc: Arnd Bergmann 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: "Luck, Tony" 
Cc: James Morris 
Cc: Andreas Schwab 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

improve sys_newuname() for compat architectures

2010-03-12T23:52:32+00:00

On an architecture that supports 32-bit compat we need to override the
reported machine in uname with the 32-bit value.  Instead of doing this
separately in every architecture introduce a COMPAT_UTS_MACHINE define in
 and apply it directly in sys_newuname().

Signed-off-by: Christoph Hellwig 
Cc: Ralf Baechle 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mundt 
Cc: Jeff Dike 
Cc: Hirokazu Takata 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: H. Peter Anvin 
Cc: Al Viro 
Cc: Arnd Bergmann 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: "Luck, Tony" 
Cc: James Morris 
Cc: Andreas Schwab 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel core: use helpers for rlimits

2010-03-06T19:26:33+00:00

Make sure compiler won't do weird things with limits.  E.g.  fetching them
twice may return 2 different values after writable limits are implemented.

I.e.  either use rlimit helpers added in commit 3e10e716abf3 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: john stultz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2010-02-28T18:31:01+00:00

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (25 commits)
  sched: Fix SCHED_MC regression caused by change in sched cpu_power
  sched: Don't use possibly stale sched_class
  kthread, sched: Remove reference to kthread_create_on_cpu
  sched: cpuacct: Use bigger percpu counter batch values for stats counters
  percpu_counter: Make __percpu_counter_add an inline function on UP
  sched: Remove member rt_se from struct rt_rq
  sched: Change usage of rt_rq->rt_se to rt_rq->tg->rt_se[cpu]
  sched: Remove unused update_shares_locked()
  sched: Use for_each_bit
  sched: Queue a deboosted task to the head of the RT prio queue
  sched: Implement head queueing for sched_rt
  sched: Extend enqueue_task to allow head queueing
  sched: Remove USER_SCHED
  sched: Fix the place where group powers are updated
  sched: Assume *balance is valid
  sched: Remove load_balance_newidle()
  sched: Unify load_balance{,_newidle}()
  sched: Add a lock break for PREEMPT=y
  sched: Remove from fwd decls
  sched: Remove rq_iterator from move_one_task
  ...

Fix up trivial conflicts in kernel/sched.c