linux-toradex.git/kernel/kmod.c, branch v2.6.27-rc4

call_usermodehelper(): increase reliability

2008-07-25T17:53:28+00:00

Presently call_usermodehelper_setup() uses GFP_ATOMIC.  but it can return
NULL _very_ easily.

GFP_ATOMIC is needed only when we can't sleep.  and, GFP_KERNEL is robust
and better.

thus, I add gfp_mask argument to call_usermodehelper_setup().

So, its callers pass the gfp_t as below:

call_usermodehelper() and call_usermodehelper_keys():
	depend on 'wait' argument.
call_usermodehelper_pipe():
	always GFP_KERNEL because always run under process context.
orderly_poweroff():
	pass to GFP_ATOMIC because may run under interrupt context.

Signed-off-by: KOSAKI Motohiro 
Cc: "Paul Menage" 
Reviewed-by: Li Zefan 
Acked-by: Jeremy Fitzhardinge 
Cc: Rusty Russell 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

flag parameters: NONBLOCK in pipe

2008-07-24T17:47:29+00:00

This patch adds O_NONBLOCK support to pipe2.  It is minimally more involved
than the patches for eventfd et.al but still trivial.  The interfaces of the
create_write_pipe and create_read_pipe helper functions were changed and the
one other caller as well.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include 
#include 
#include 
#include 

#ifndef __NR_pipe2
# ifdef __x86_64__
#  define __NR_pipe2 293
# elif defined __i386__
#  define __NR_pipe2 331
# else
#  error "need __NR_pipe2"
# endif
#endif

int
main (void)
{
  int fds[2];
  if (syscall (__NR_pipe2, fds, 0) == -1)
    {
      puts ("pipe2(0) failed");
      return 1;
    }
  for (int i = 0; i < 2; ++i)
    {
      int fl = fcntl (fds[i], F_GETFL);
      if (fl == -1)
        {
          puts ("fcntl failed");
          return 1;
        }
      if (fl & O_NONBLOCK)
        {
          printf ("pipe2(0) set non-blocking mode for fds[%d]\n", i);
          return 1;
        }
      close (fds[i]);
    }

  if (syscall (__NR_pipe2, fds, O_NONBLOCK) == -1)
    {
      puts ("pipe2(O_NONBLOCK) failed");
      return 1;
    }
  for (int i = 0; i < 2; ++i)
    {
      int fl = fcntl (fds[i], F_GETFL);
      if (fl == -1)
        {
          puts ("fcntl failed");
          return 1;
        }
      if ((fl & O_NONBLOCK) == 0)
        {
          printf ("pipe2(O_NONBLOCK) does not set non-blocking mode for fds[%d]\n", i);
          return 1;
        }
      close (fds[i]);
    }

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Ulrich Drepper 
Acked-by: Davide Libenzi 
Cc: Michael Kerrisk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

remove CONFIG_KMOD from core kernel code

2008-07-22T09:24:31+00:00

Always compile request_module when the kernel allows modules.

Signed-off-by: Johannes Berg 
Signed-off-by: Rusty Russell

[PATCH] split linux/file.h

2008-05-01T17:08:16+00:00

Initial splitoff of the low-level stuff; taken to fdtable.h

Signed-off-by: Al Viro

generic: use new set_cpus_allowed_ptr function

2008-04-19T17:44:58+00:00

  * 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 
Signed-off-by: Ingo Molnar

Dont touch fs_struct in usermodehelper

2008-02-15T05:13:32+00:00

This test seems to be unnecessary since we always have rootfs mounted before
calling a usermodehelper.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Jan Blunck 
Acked-by: Christoph Hellwig 
Acked-by: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Fix unbalanced helper_lock in kernel/kmod.c

2008-01-17T23:38:59+00:00

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 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Restore call_usermodehelper_pipe() behaviour

2007-09-12T00:21:20+00:00

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 
Acked-by: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel-doc fix for kmod.c

2007-07-26T18:33:06+00:00

Fix kmod.c:
Warning(linux-2.6.23-rc1//kernel/kmod.c:364): No description found for parameter 'envp'

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

PM: prevent frozen user mode helpers from failing the freezing of tasks

2007-07-19T17:04:42+00:00

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 , Pavel Machek
 and Oleg Nesterov  for reviewing the
previous versions of this patch and for very useful comments.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Uli Luckas 
Acked-by: Nigel Cunningham 
Acked-by: Pavel Machek 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds