• Luis R. Rodriguez's avatar
    scripts: add Linux .cocciconfig for coccinelle · dd951fc1
    Luis R. Rodriguez authored
    Coccinelle supports reading .cocciconfig, the order of precedence for
    variables for .cocciconfig is as follows:
    
     o Your current user's home directory is processed first
     o Your directory from which spatch is called is processed next
     o The directory provided with the --dir option is processed last, if used
    
    Since coccicheck runs through make, it naturally runs from the kernel
    proper dir, as such the second rule above would be implied for picking up a
    .cocciconfig when using 'make coccicheck'.
    
    'make coccicheck' also supports using M= targets.If you do not supply
    any M= target, it is assumed you want to target the entire kernel.
    The kernel coccicheck script has:
    
        if [ "$KBUILD_EXTMOD" = "" ] ; then
            OPTIONS="--dir $srctree $COCCIINCLUDE"
        else
            OPTIONS="--dir $KBUILD_EXTMOD $COCCIINCLUDE"
        fi
    
    KBUILD_EXTMOD is set when an explicit target with M= is used. For both cases
    the spatch --dir argument is used, as such third rule applies when
    whether M= is used or not, and when M= is used the target directory can
    have its own .cocciconfig file. When M= is not passed as an argument to
    coccicheck the target directory is the same as the directory from where
    spatch was called.
    
    If not using the kernel's coccicheck target, keep the above precedence order
    logic of .cocciconfig reading. If using the kernel's coccicheck target,
    override any of the kernel's .coccicheck's settings using SPFLAGS.
    
    We help Coccinelle when used against Linux with a set of sensible defaults
    options for Linux with our own Linux .cocciconfig. This hints to coccinelle
    git can be used for 'git grep' queries over coccigrep. A timeout of 200
    seconds should suffice for now.
    
    The options picked up by coccinelle when reading a .cocciconfig do not appear
    as arguments to spatch processes running on your system, to confirm what
    options will be used by Coccinelle run:
    
      spatch --print-options-only
    
    You can override with your own preferred index option by using SPFLAGS.
    Coccinelle supports both glimpse and idutils. Glimpse had historically
    provided the best performance, however recent benchmarks reveal idutils
    is performing just as well. Due to some recent fixes however you however
    will need at least coccinelle >= 1.0.6 if using idutils.
    
    Coccinelle carries a script scripts/idutils_index.sh which creates the
    idutils database with as follows:
    
        mkid -i C --output .id-utils.index
    
    If using just "--use-idutils" coccinelle expects your idutils database to be
    on the top level of the kernel as a file named ".id-utils.index". If you do
    not use this you can symlink your database file to it, or you can specify the
    database file following the "--use-idutils" argument. Examples:
    
        make SPFLAGS=--use-idutils coccicheck
    
    This assumes you have $srctree/.id-utils.index, where $srctree is
    the top level of the kernel.
    
        make SPFLAGS="--use-idutils /full-path/to/ID" coccicheck
    
    Here you specify the full path of the idutils ID database. Using
    .cocciconfig is possible, however given the order of precedence followed
    by Coccinelle, and since the kernel now carries its own .cocciconfig,
    you will need to use SPFLAGS to use idutils if desired.
    
    v4:
    
    o Recommend upgrade for using idutils with coccinelle due to some
      recent fixes.
    
    o Refer to using --print-options-only for testing what options are
      picked up by .cocciconfig reading.
    
    o Expand commit log considerably explaining *why* .cocconfig from
      two precedence rules are used when using coccicheck, and how to
      properly override these if needed.
    
    o Expand Documentation/coccinelle.txt
    
    v3: Expand commit log a bit more
    Signed-off-by: 's avatarLuis R. Rodriguez <mcgrof@kernel.org>
    Acked-by: 's avatarJulia Lawall <julia.lawall@lip6.fr>
    Signed-off-by: 's avatarMichal Marek <mmarek@suse.com>
    dd951fc1