01 Jul, 2011

1 commit


06 Jun, 2011

1 commit


02 Jun, 2011

1 commit


24 May, 2011

1 commit


21 Dec, 2010

1 commit


11 Nov, 2010

1 commit


30 Mar, 2010

1 commit

  • …it slab.h inclusion from percpu.h

    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 <tj@kernel.org>
    Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

    Tejun Heo
     

01 Mar, 2010

1 commit


11 Jan, 2010

1 commit


04 Dec, 2009

2 commits

  • With CLONE_IO, parent's io_context->nr_tasks is incremented, but never
    decremented whenever copy_process() fails afterwards, which prevents
    exit_io_context() from calling IO schedulers exit functions.

    Give a task_struct to exit_io_context(), and call exit_io_context() instead of
    put_io_context() in copy_process() cleanup path.

    Signed-off-by: Louis Rilling
    Signed-off-by: Jens Axboe

    Louis Rilling
     
  • With CLONE_IO, copy_io() increments both ioc->refcount and ioc->nr_tasks.
    However exit_io_context() only decrements ioc->refcount if ioc->nr_tasks
    reaches 0.

    Always call put_io_context() in exit_io_context().

    Signed-off-by: Louis Rilling
    Signed-off-by: Jens Axboe

    Louis Rilling
     

11 Jun, 2009

1 commit

  • Currently io_context has an atomic_t(32-bit) as refcount. In the case of
    cfq, for each device against whcih a task does I/O, a reference to the
    io_context would be taken. And when there are multiple process sharing
    io_contexts(CLONE_IO) would also have a reference to the same io_context.

    Theoretically the possible maximum number of processes sharing the same
    io_context + the number of disks/cfq_data referring to the same io_context
    can overflow the 32-bit counter on a very high-end machine.

    Even though it is an improbable case, let us make it atomic_long_t.

    Signed-off-by: Nikanth Karthikesan
    Signed-off-by: Andrew Morton
    Signed-off-by: Jens Axboe

    Nikanth Karthikesan
     

07 May, 2008

1 commit

  • put_io_context() drops the RCU read lock before calling into cfq_dtor(),
    however we need to hold off freeing there before grabbing and
    dereferencing the first object on the list.

    So extend the rcu_read_lock() scope to cover the calling of cfq_dtor(),
    and optimize cfq_free_io_context() to use a new variant for
    call_for_each_cic() that assumes the RCU read lock is already held.

    Hit in the wild by Alexey Dobriyan

    Signed-off-by: Jens Axboe

    Jens Axboe
     

19 Feb, 2008

2 commits


01 Feb, 2008

1 commit

  • It blindly copies everything in the io_context, including the lock.
    That doesn't work so well for either lock ordering or lockdep.

    There seems zero point in swapping io contexts on a request to request
    merge, so the best point of action is to just remove it.

    Signed-off-by: Jens Axboe

    Jens Axboe
     

30 Jan, 2008

1 commit