Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 523 insertions, 0 deletions

diff --git a/Documentation/dev-tools/coccinelle.rst b/Documentation/dev-tools/coccinelle.rst
new file mode 100644
index 000000000..b8ecb481d
--- /dev/null
+++ b/Documentation/dev-tools/coccinelle.rst
@@ -0,0 +1,523 @@
+.. Copyright 2010 Nicolas Palix <npalix@diku.dk>
+.. Copyright 2010 Julia Lawall <julia@diku.dk>
+.. Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr>
+
+.. highlight:: none
+
+.. _devtools_coccinelle:
+
+Coccinelle
+==========
+
+Coccinelle is a tool for pattern matching and text transformation that has
+many uses in kernel development, including the application of complex,
+tree-wide patches and detection of problematic programming patterns.
+
+Getting Coccinelle
+------------------
+
+The semantic patches included in the kernel use features and options
+which are provided by Coccinelle version 1.0.0-rc11 and above.
+Using earlier versions will fail as the option names used by
+the Coccinelle files and coccicheck have been updated.
+
+Coccinelle is available through the package manager
+of many distributions, e.g. :
+
+ - Debian
+ - Fedora
+ - Ubuntu
+ - OpenSUSE
+ - Arch Linux
+ - Gentoo
+ - NetBSD
+ - FreeBSD
+
+Some distribution packages are obsolete and it is recommended
+to use the latest version released from the Coccinelle homepage at
+https://coccinelle.gitlabpages.inria.fr/website
+
+Or from Github at:
+
+https://github.com/coccinelle/coccinelle
+
+Once you have it, run the following commands::
+
+        ./autogen
+        ./configure
+        make
+
+as a regular user, and install it with::
+
+        sudo make install
+
+More detailed installation instructions to build from source can be
+found at:
+
+https://github.com/coccinelle/coccinelle/blob/master/install.txt
+
+Supplemental documentation
+--------------------------
+
+For supplemental documentation refer to the wiki:
+
+https://bottest.wiki.kernel.org/coccicheck.html
+
+The wiki documentation always refers to the linux-next version of the script.
+
+For Semantic Patch Language(SmPL) grammar documentation refer to:
+
+https://coccinelle.gitlabpages.inria.fr/website/docs/main_grammar.html
+
+Using Coccinelle on the Linux kernel
+------------------------------------
+
+A Coccinelle-specific target is defined in the top level
+Makefile. This target is named ``coccicheck`` and calls the ``coccicheck``
+front-end in the ``scripts`` directory.
+
+Four basic modes are defined: ``patch``, ``report``, ``context``, and
+``org``. The mode to use is specified by setting the MODE variable with
+``MODE=<mode>``.
+
+- ``patch`` proposes a fix, when possible.
+
+- ``report`` generates a list in the following format:
+  file:line:column-column: message
+
+- ``context`` highlights lines of interest and their context in a
+  diff-like style. Lines of interest are indicated with ``-``.
+
+- ``org`` generates a report in the Org mode format of Emacs.
+
+Note that not all semantic patches implement all modes. For easy use
+of Coccinelle, the default mode is "report".
+
+Two other modes provide some common combinations of these modes.
+
+- ``chain`` tries the previous modes in the order above until one succeeds.
+
+- ``rep+ctxt`` runs successively the report mode and the context mode.
+  It should be used with the C option (described later)
+  which checks the code on a file basis.
+
+Examples
+~~~~~~~~
+
+To make a report for every semantic patch, run the following command::
+
+		make coccicheck MODE=report
+
+To produce patches, run::
+
+		make coccicheck MODE=patch
+
+
+The coccicheck target applies every semantic patch available in the
+sub-directories of ``scripts/coccinelle`` to the entire Linux kernel.
+
+For each semantic patch, a commit message is proposed.  It gives a
+description of the problem being checked by the semantic patch, and
+includes a reference to Coccinelle.
+
+As with any static code analyzer, Coccinelle produces false
+positives. Thus, reports must be carefully checked, and patches
+reviewed.
+
+To enable verbose messages set the V= variable, for example::
+
+   make coccicheck MODE=report V=1
+
+By default, coccicheck will print debug logs to stdout and redirect stderr to
+/dev/null. This can make coccicheck output difficult to read and understand.
+Debug and error messages can instead be written to a debug file instead by
+setting the ``DEBUG_FILE`` variable::
+
+    make coccicheck MODE=report DEBUG_FILE="cocci.log"
+
+Coccinelle cannot overwrite a debug file. Instead of repeatedly deleting a log
+file, you could include the datetime in the debug file name::
+
+    make coccicheck MODE=report DEBUG_FILE="cocci-$(date -Iseconds).log"
+
+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, and the return value of the ``make coccicheck``
+command captures this return value.
+
+Using Coccinelle with a single semantic patch
+---------------------------------------------
+
+The optional make variable COCCI can be used to check a single
+semantic patch. In that case, the variable must be initialized with
+the name of the semantic patch to apply.
+
+For instance::
+
+	make coccicheck COCCI=<my_SP.cocci> MODE=patch
+
+or::
+
+	make coccicheck COCCI=<my_SP.cocci> MODE=report
+
+
+Controlling Which Files are Processed by Coccinelle
+---------------------------------------------------
+
+By default the entire kernel source tree is checked.
+
+To apply Coccinelle to a specific directory, ``M=`` can be used.
+For example, to check drivers/net/wireless/ one may write::
+
+    make coccicheck M=drivers/net/wireless/
+
+To apply Coccinelle on a file basis, instead of a directory basis, the
+C variable is used by the makefile to select which files to work with.
+This variable can be used to run scripts for the entire kernel, a
+specific directory, or for a single file.
+
+For example, to check drivers/bluetooth/bfusb.c, the value 1 is
+passed to the C variable to check files that make considers
+need to be compiled.::
+
+    make C=1 CHECK=scripts/coccicheck drivers/bluetooth/bfusb.o
+
+The value 2 is passed to the C variable to check files regardless of
+whether they need to be compiled or not.::
+
+    make C=2 CHECK=scripts/coccicheck drivers/bluetooth/bfusb.o
+
+In these modes, which work on a file basis, there is no information
+about semantic patches displayed, and no commit message proposed.
+
+This runs every semantic patch in scripts/coccinelle by default. The
+COCCI variable may additionally be used to only apply a single
+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.
+
+An easier approach to debug running Coccinelle against SmPL patches is to ask
+coccicheck to redirect stderr to a debug file. As mentioned in the examples, 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 example
+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
+
+err.log will now have the profiling information, while stdout will
+provide some progress information as Coccinelle moves forward with
+work.
+
+NOTE:
+
+DEBUG_FILE support is only supported when using coccinelle >= 1.0.2.
+
+Currently, DEBUG_FILE support is only available to check folders, and
+not single files. This is because checking a single file requires spatch
+to be called twice leading to DEBUG_FILE being set both times to the same value,
+giving rise to an error.
+
+.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:
+
+- Your current user's home directory is processed first
+- Your directory from which spatch is called is processed next
+- The directory provided with the ``--dir`` option is processed last, if used
+
+``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::
+
+    OPTIONS="--dir $srcroot $COCCIINCLUDE"
+
+Here, $srcroot refers to the source directory of the target: it points to the
+external module's source directory when M= used, and otherwise, to the kernel
+source directory. The third rule ensures the spatch reads the .cocciconfig from
+the target directory, allowing external modules to have their own .cocciconfig
+file.
+
+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 default
+options for Linux with our own Linux .cocciconfig. This hints to coccinelle
+that 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. 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
+require external tools for indexing the code. None of them is
+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
+a minimum 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
+------------------------------
+
+New semantic patches can be proposed and submitted by kernel
+developers. For sake of clarity, they should be organized in the
+sub-directories of ``scripts/coccinelle/``.
+
+
+Detailed description of the ``report`` mode
+-------------------------------------------
+
+``report`` generates a list in the following format::
+
+  file:line:column-column: message
+
+Example
+~~~~~~~
+
+Running::
+
+	make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
+
+will execute the following part of the SmPL script::
+
+   <smpl>
+   @r depends on !context && !patch && (org || report)@
+   expression x;
+   position p;
+   @@
+
+     ERR_PTR@p(PTR_ERR(x))
+
+   @script:python depends on report@
+   p << r.p;
+   x << r.x;
+   @@
+
+   msg="ERR_CAST can be used with %s" % (x)
+   coccilib.report.print_report(p[0], msg)
+   </smpl>
+
+This SmPL excerpt generates entries on the standard output, as
+illustrated below::
+
+    /home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
+    /home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
+    /home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
+
+
+Detailed description of the ``patch`` mode
+------------------------------------------
+
+When the ``patch`` mode is available, it proposes a fix for each problem
+identified.
+
+Example
+~~~~~~~
+
+Running::
+
+	make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
+
+will execute the following part of the SmPL script::
+
+    <smpl>
+    @ depends on !context && patch && !org && !report @
+    expression x;
+    @@
+
+    - ERR_PTR(PTR_ERR(x))
+    + ERR_CAST(x)
+    </smpl>
+
+This SmPL excerpt generates patch hunks on the standard output, as
+illustrated below::
+
+    diff -u -p a/crypto/ctr.c b/crypto/ctr.c
+    --- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
+    +++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
+    @@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
+ 	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
+ 				  CRYPTO_ALG_TYPE_MASK);
+ 	if (IS_ERR(alg))
+    -		return ERR_PTR(PTR_ERR(alg));
+    +		return ERR_CAST(alg);
+
+ 	/* Block size must be >= 4 bytes. */
+ 	err = -EINVAL;
+
+Detailed description of the ``context`` mode
+--------------------------------------------
+
+``context`` highlights lines of interest and their context
+in a diff-like style.
+
+      **NOTE**: The diff-like output generated is NOT an applicable patch. The
+      intent of the ``context`` mode is to highlight the important lines
+      (annotated with minus, ``-``) and gives some surrounding context
+      lines around. This output can be used with the diff mode of
+      Emacs to review the code.
+
+Example
+~~~~~~~
+
+Running::
+
+	make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
+
+will execute the following part of the SmPL script::
+
+    <smpl>
+    @ depends on context && !patch && !org && !report@
+    expression x;
+    @@
+
+    * ERR_PTR(PTR_ERR(x))
+    </smpl>
+
+This SmPL excerpt generates diff hunks on the standard output, as
+illustrated below::
+
+    diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
+    --- /home/user/linux/crypto/ctr.c	2010-05-26 10:49:38.000000000 +0200
+    +++ /tmp/nothing
+    @@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
+ 	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
+ 				  CRYPTO_ALG_TYPE_MASK);
+ 	if (IS_ERR(alg))
+    -		return ERR_PTR(PTR_ERR(alg));
+
+ 	/* Block size must be >= 4 bytes. */
+ 	err = -EINVAL;
+
+Detailed description of the ``org`` mode
+----------------------------------------
+
+``org`` generates a report in the Org mode format of Emacs.
+
+Example
+~~~~~~~
+
+Running::
+
+	make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
+
+will execute the following part of the SmPL script::
+
+    <smpl>
+    @r depends on !context && !patch && (org || report)@
+    expression x;
+    position p;
+    @@
+
+      ERR_PTR@p(PTR_ERR(x))
+
+    @script:python depends on org@
+    p << r.p;
+    x << r.x;
+    @@
+
+    msg="ERR_CAST can be used with %s" % (x)
+    msg_safe=msg.replace("[","@(").replace("]",")")
+    coccilib.org.print_todo(p[0], msg_safe)
+    </smpl>
+
+This SmPL excerpt generates Org entries on the standard output, as
+illustrated below::
+
+    * TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
+    * TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
+    * TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]