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-rw-r--r--Documentation/coccinelle.txt148
1 files changed, 147 insertions, 1 deletions
diff --git a/Documentation/coccinelle.txt b/Documentation/coccinelle.txt
index 7f773d51fdd9..01fb1dae3163 100644
--- a/Documentation/coccinelle.txt
+++ b/Documentation/coccinelle.txt
@@ -38,6 +38,15 @@ as a regular user, and install it with
sudo make install
+ Supplemental documentation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For supplemental documentation refer to the wiki:
+
+https://bottest.wiki.kernel.org/coccicheck
+
+The wiki documentation always refers to the linux-next version of the script.
+
Using Coccinelle on the Linux kernel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -94,11 +103,26 @@ To enable verbose messages set the V= variable, for example:
make coccicheck MODE=report V=1
+ Coccinelle parallelization
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
By default, coccicheck tries to run as parallel as possible. To change
the parallelism, set the J= variable. For example, to run across 4 CPUs:
make coccicheck MODE=report J=4
+As of Coccinelle 1.0.2 Coccinelle uses Ocaml parmap for parallelization,
+if support for this is detected you will benefit from parmap parallelization.
+
+When parmap is enabled coccicheck will enable dynamic load balancing by using
+'--chunksize 1' argument, this ensures we keep feeding threads with work
+one by one, so that we avoid the situation where most work gets done by only
+a few threads. With dynamic load balancing, if a thread finishes early we keep
+feeding it more work.
+
+When parmap is enabled, if an error occurs in Coccinelle, this error
+value is propagated back, the return value of the 'make coccicheck'
+captures this return value.
Using Coccinelle with a single semantic patch
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -142,15 +166,118 @@ semantic patch as shown in the previous section.
The "report" mode is the default. You can select another one with the
MODE variable explained above.
+ Debugging Coccinelle SmPL patches
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Using coccicheck is best as it provides in the spatch command line
+include options matching the options used when we compile the kernel.
+You can learn what these options are by using V=1, you could then
+manually run Coccinelle with debug options added.
+
+Alternatively you can debug running Coccinelle against SmPL patches
+by asking for stderr to be redirected to stderr, by default stderr
+is redirected to /dev/null, if you'd like to capture stderr you
+can specify the DEBUG_FILE="file.txt" option to coccicheck. For
+instance:
+
+ rm -f cocci.err
+ make coccicheck COCCI=scripts/coccinelle/free/kfree.cocci MODE=report DEBUG_FILE=cocci.err
+ cat cocci.err
+
+You can use SPFLAGS to add debugging flags, for instance you may want to
+add both --profile --show-trying to SPFLAGS when debugging. For instance
+you may want to use:
+
+ rm -f err.log
+ export COCCI=scripts/coccinelle/misc/irqf_oneshot.cocci
+ make coccicheck DEBUG_FILE="err.log" MODE=report SPFLAGS="--profile --show-trying" M=./drivers/mfd/arizona-irq.c
+
+err.log will now have the profiling information, while stdout will
+provide some progress information as Coccinelle moves forward with
+work.
+
+DEBUG_FILE support is only supported when using coccinelle >= 1.2.
+
+ .cocciconfig support
+~~~~~~~~~~~~~~~~~~~~~~
+
+Coccinelle supports reading .cocciconfig for default Coccinelle options that
+should be used every time spatch is spawned, 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. Take
+note that when there are conflicting options Coccinelle takes precedence for
+the last options passed. Using .cocciconfig is possible to use idutils, however
+given the order of precedence followed by Coccinelle, since the kernel now
+carries its own .cocciconfig, you will need to use SPFLAGS to use idutils if
+desired. See below section "Additional flags" for more details on how to use
+idutils.
+
Additional flags
~~~~~~~~~~~~~~~~~~
Additional flags can be passed to spatch through the SPFLAGS
-variable.
+variable. This works as Coccinelle respects the last flags
+given to it when options are in conflict.
make SPFLAGS=--use-glimpse coccicheck
+
+Coccinelle supports idutils as well but requires coccinelle >= 1.0.6.
+When no ID file is specified coccinelle assumes your ID database file
+is in the file .id-utils.index on the top level of the kernel, coccinelle
+carries a script scripts/idutils_index.sh which creates the database with
+
+ mkid -i C --output .id-utils.index
+
+If you have another database filename you can also just symlink with this
+name.
+
make SPFLAGS=--use-idutils coccicheck
+Alternatively you can specify the database filename explicitly, for
+instance:
+
+ make SPFLAGS="--use-idutils /full-path/to/ID" coccicheck
+
See spatch --help to learn more about spatch options.
Note that the '--use-glimpse' and '--use-idutils' options
@@ -159,6 +286,25 @@ thus active by default. However, by indexing the code with
one of these tools, and according to the cocci file used,
spatch could proceed the entire code base more quickly.
+ SmPL patch specific options
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+SmPL patches can have their own requirements for options passed
+to Coccinelle. SmPL patch specific options can be provided by
+providing them at the top of the SmPL patch, for instance:
+
+// Options: --no-includes --include-headers
+
+ SmPL patch Coccinelle requirements
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As Coccinelle features get added some more advanced SmPL patches
+may require newer versions of Coccinelle. If an SmPL patch requires
+at least a version of Coccinelle, this can be specified as follows,
+as an example if requiring at least Coccinelle >= 1.0.5:
+
+// Requires: 1.0.5
+
Proposing new semantic patches
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~