• Tejun Heo's avatar
    include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
    Tejun Heo authored
    include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit 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: default avatarTejun Heo <tj@kernel.org>
    Guess-its-ok-by: default avatarChristoph Lameter <cl@linux-foundation.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
    5a0e3ad6
it8152.c 8.88 KB