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  1. Oct 18, 2022
  3. Jun 13, 2022
    • Niklas Söderlund's avatar
      scripts: kernel-doc: Always increment warnings counter · df4bf98e
      Niklas Söderlund authored 
      
Some warnings do not increment the warnings counter making the behavior
of running kernel-doc with -Werror unlogical as some warnings will be
generated but not treated as errors.

Fix this by creating a helper function that always incrementing the
warnings counter every time a warning is emitted. There is one location
in get_sphinx_version() where a warning is not touched as it concerns
the execution environment of the kernel-doc and not the documentation
being processed.

Incrementing the counter only have effect when running kernel-doc in
either verbose mode (-v or environment variable KBUILD_VERBOSE) or when
treating warnings as errors (-Werror or environment variable
KDOC_WERROR). In both cases the number of warnings printed is printed to
stderr and for the later the exit code of kernel-doc is non-zero if
warnings where encountered.

Simple test case to demo one of the warnings,

    $ cat test.c
    /**
     * foo() - Description
     */
    int bar();

    # Without this change
    $ ./scripts/kernel-doc -Werror -none test.c
    test.c:4: warning: expecting prototype for foo(). Prototype was for
    bar() instead

    # With this change
    $ ./scripts/kernel-doc -Werror -none test.c
    test.c:4: warning: expecting prototype for foo(). Prototype was for
    bar() instead
    1 warnings as Errors

Signed-off-by: default avatarNiklas Söderlund <niklas.soderlund@corigine.com>
Link: https://lore.kernel.org/r/20220613090510.3088294-1-niklas.soderlund@corigine.com


Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      df4bf98e
  5. Mar 28, 2022
  7. Feb 24, 2022
  9. Nov 01, 2021
  11. Oct 18, 2021
    • Kees Cook's avatar
      stddef: Introduce DECLARE_FLEX_ARRAY() helper · 3080ea55
      Kees Cook authored 
      There are many places where kernel code wants to have several different
typed trailing flexible arrays. This would normally be done with multiple
flexible arrays in a union, but since GCC and Clang don't (on the surface)
allow this, there have been many open-coded workarounds, usually involving
neighboring 0-element arrays at the end of a structure. For example,
instead of something like this:

struct thing {
	...
	union {
		struct type1 foo[];
		struct type2 bar[];
	};
};

code works around the compiler with:

struct thing {
	...
	struct type1 foo[0];
	struct type2 bar[];
};

Another case is when a flexible array is wanted as the single member
within a struct (which itself is usually in a union). For example, this
would be worked around as:

union many {
	...
	struct {
		struct type3 baz[0];
	};
};

These kinds of work-arounds cause problems with size checks against such
zero-element arrays (for example when building with -Warray-bounds and
-Wzero-length-bounds, and with the coming FORTIFY_SOURCE improvements),
so they must all be converted to "real" flexible arrays, avoiding warnings
like this:

fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree':
fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds]
  209 |    anode->btree.u.internal[0].down = cpu_to_le32(a);
      |    ~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from fs/hpfs/hpfs_fn.h:26,
                 from fs/hpfs/anode.c:10:
fs/hpfs/hpfs.h:412:32: note: while referencing 'internal'
  412 |     struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving
      |                                ^~~~~~~~

drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg':
drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds]
  360 |  tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len];
      |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22,
                 from drivers/net/can/usb/etas_es58x/es58x_fd.c:17:
drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg'
  231 |   u8 raw_msg[0];
      |      ^~~~~~~

However, it _is_ entirely possible to have one or more flexible arrays
in a struct or union: it just has to be in another struct. And since it
cannot be alone in a struct, such a struct must have at least 1 other
named member -- but that member can be zero sized. Wrap all this nonsense
into the new DECLARE_FLEX_ARRAY() in support of having flexible arrays
in unions (or alone in a struct).

As with struct_group(), since this is needed in UAPI headers as well,
implement the core there, with a non-UAPI wrapper.

Additionally update kernel-doc to understand its existence.

https://github.com/KSPP/linux/issues/137



Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      3080ea55
  13. Oct 12, 2021
  15. Sep 25, 2021
    • Kees Cook's avatar
      stddef: Introduce struct_group() helper macro · 50d7bd38
      Kees Cook authored 
      
Kernel code has a regular need to describe groups of members within a
structure usually when they need to be copied or initialized separately
from the rest of the surrounding structure. The generally accepted design
pattern in C is to use a named sub-struct:

	struct foo {
		int one;
		struct {
			int two;
			int three, four;
		} thing;
		int five;
	};

This would allow for traditional references and sizing:

	memcpy(&dst.thing, &src.thing, sizeof(dst.thing));

However, doing this would mean that referencing struct members enclosed
by such named structs would always require including the sub-struct name
in identifiers:

	do_something(dst.thing.three);

This has tended to be quite inflexible, especially when such groupings
need to be added to established code which causes huge naming churn.
Three workarounds exist in the kernel for this problem, and each have
other negative properties.

To avoid the naming churn, there is a design pattern of adding macro
aliases for the named struct:

	#define f_three thing.three

This ends up polluting the global namespace, and makes it difficult to
search for identifiers.

Another common work-around in kernel code avoids the pollution by avoiding
the named struct entirely, instead identifying the group's boundaries using
either a pair of empty anonymous structs of a pair of zero-element arrays:

	struct foo {
		int one;
		struct { } start;
		int two;
		int three, four;
		struct { } finish;
		int five;
	};

	struct foo {
		int one;
		int start[0];
		int two;
		int three, four;
		int finish[0];
		int five;
	};

This allows code to avoid needing to use a sub-struct named for member
references within the surrounding structure, but loses the benefits of
being able to actually use such a struct, making it rather fragile. Using
these requires open-coded calculation of sizes and offsets. The efforts
made to avoid common mistakes include lots of comments, or adding various
BUILD_BUG_ON()s. Such code is left with no way for the compiler to reason
about the boundaries (e.g. the "start" object looks like it's 0 bytes
in length), making bounds checking depend on open-coded calculations:

	if (length > offsetof(struct foo, finish) -
		     offsetof(struct foo, start))
		return -EINVAL;
	memcpy(&dst.start, &src.start, offsetof(struct foo, finish) -
				       offsetof(struct foo, start));

However, the vast majority of places in the kernel that operate on
groups of members do so without any identification of the grouping,
relying either on comments or implicit knowledge of the struct contents,
which is even harder for the compiler to reason about, and results in
even more fragile manual sizing, usually depending on member locations
outside of the region (e.g. to copy "two" and "three", use the start of
"four" to find the size):

	BUILD_BUG_ON((offsetof(struct foo, four) <
		      offsetof(struct foo, two)) ||
		     (offsetof(struct foo, four) <
		      offsetof(struct foo, three));
	if (length > offsetof(struct foo, four) -
		     offsetof(struct foo, two))
		return -EINVAL;
	memcpy(&dst.two, &src.two, length);

In order to have a regular programmatic way to describe a struct
region that can be used for references and sizing, can be examined for
bounds checking, avoids forcing the use of intermediate identifiers,
and avoids polluting the global namespace, introduce the struct_group()
macro. This macro wraps the member declarations to create an anonymous
union of an anonymous struct (no intermediate name) and a named struct
(for references and sizing):

	struct foo {
		int one;
		struct_group(thing,
			int two;
			int three, four;
		);
		int five;
	};

	if (length > sizeof(src.thing))
		return -EINVAL;
	memcpy(&dst.thing, &src.thing, length);
	do_something(dst.three);

There are some rare cases where the resulting struct_group() needs
attributes added, so struct_group_attr() is also introduced to allow
for specifying struct attributes (e.g. __align(x) or __packed).
Additionally, there are places where such declarations would like to
have the struct be tagged, so struct_group_tagged() is added.

Given there is a need for a handful of UAPI uses too, the underlying
__struct_group() macro has been defined in UAPI so it can be used there
too.

To avoid confusing scripts/kernel-doc, hide the macro from its struct
parsing.

Co-developed-by: default avatarKeith Packard <keithp@keithp.com>
Signed-off-by: default avatarKeith Packard <keithp@keithp.com>
Acked-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/lkml/20210728023217.GC35706@embeddedor


Enhanced-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/lkml/41183a98-bdb9-4ad6-7eab-5a7292a6df84@rasmusvillemoes.dk


Enhanced-by: default avatarDan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/lkml/1d9a2e6df2a9a35b2cdd50a9a68cac5991e7e5f0.camel@intel.com


Enhanced-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://lore.kernel.org/lkml/YQKa76A6XuFqgM03@phenom.ffwll.local


Acked-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      50d7bd38
  17. Aug 12, 2021
  19. May 17, 2021
  21. Apr 27, 2021
  23. Apr 15, 2021
  25. Mar 29, 2021
  27. Mar 26, 2021
  29. Mar 25, 2021
  31. Mar 09, 2021
  33. Mar 08, 2021
  35. Mar 07, 2021
  37. Feb 22, 2021
  39. Jan 28, 2021
  41. Jan 18, 2021
    • Mauro Carvalho Chehab's avatar
      scripts: kernel-doc: validate kernel-doc markup with the actual names · 52042e2d
      Mauro Carvalho Chehab authored 
      
Kernel-doc currently expects that the kernel-doc markup to come
just before the function/enum/struct/union/typedef prototype.

Yet, if it find things like:

	/**
	 * refcount_add - add a value to a refcount
	 * @i: the value to add to the refcount
	 * @r: the refcount
	 */
	static inline void __refcount_add(int i, refcount_t *r, int *oldp);
	static inline void refcount_add(int i, refcount_t *r);

Kernel-doc will do the wrong thing:

	foobar.h:6: warning: Function parameter or member 'oldp' not described in '__refcount_add'
	.. c:function:: void __refcount_add (int i, refcount_t *r, int *oldp)

	   add a value to a refcount

	**Parameters**

	``int i``
	  the value to add to the refcount

	``refcount_t *r``
	  the refcount

	``int *oldp``
	  *undescribed*

Basically, it will document "__refcount_add" with the kernel-doc
markup for refcount_add.

If both functions have the same arguments, this won't even
produce any warning!

Add a logic to check if the kernel-doc identifier matches the actual
name of the C function or data structure that will be documented.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/081546f141a496d6cabb99a4adc140444c705e93.1610610937.git.mchehab+huawei@kernel.org


Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      52042e2d
  43. Dec 03, 2020
  45. Nov 13, 2020
  47. Oct 28, 2020
  49. Oct 15, 2020
    • Mauro Carvalho Chehab's avatar
      scripts: kernel-doc: try to use c:function if possible · 6e9e4158
      Mauro Carvalho Chehab authored 
      There are a few namespace clashes by using c:macro everywhere:

basically, when using it, we can't have something like:

	.. c:struct:: pwm_capture

	.. c:macro:: pwm_capture

So, we need to use, instead:

	.. c:function:: int pwm_capture (struct pwm_device * pwm, struct pwm_capture * result, unsigned long timeout)

for the function declaration.

The kernel-doc change was proposed by Jakob Lykke Andersen here:

	https://github.com/jakobandersen/linux_docs/commit/6fd2076ec001cca7466857493cd678df4dfe4a65



Although I did a different implementation.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
      6e9e4158
    • Mauro Carvalho Chehab's avatar
      scripts: kernel-doc: fix line number handling · 5ef09c96
      Mauro Carvalho Chehab authored 
      
Address several issues related to pointing to the wrong line
number:

1) ensure that line numbers will always be initialized

   When section is the default (Description), the line number
   is not initializing, producing this:

	$ ./scripts/kernel-doc --enable-lineno ./drivers/media/v4l2-core/v4l2-mem2mem.c|less

	**Description**

	#define LINENO 0
	In case of streamoff or release called on any context,
	1] If the context is currently running, then abort job will be called
	2] If the context is queued, then the context will be removed from
	   the job_queue

  Which is not right. Ensure that the line number will always
  be there. After applied, the result now points to the right location:

	**Description**

	#define LINENO 410
	In case of streamoff or release called on any context,
	1] If the context is currently running, then abort job will be called
	2] If the context is queued, then the context will be removed from
	   the job_queue

2) The line numbers for function prototypes are always + 1,
   because it is taken at the line after handling the prototype.
   Change the logic to point to the next line after the /** */
   block;

3) The "DOC:" line number should point to the same line as this
   markup is found, and not to the next one.

Probably part of the issues were due to a but that was causing
the line number offset to be incremented by one, if --export
were used.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
      5ef09c96
    • Mauro Carvalho Chehab's avatar
      scripts: kernel-doc: allow passing desired Sphinx C domain dialect · 93351d41
      Mauro Carvalho Chehab authored 
      
When kernel-doc is called via kerneldoc.py, there's no need to
auto-detect the Sphinx version, as the Sphinx module already
knows it. So, add an optional parameter to allow changing the
Sphinx dialect.

As kernel-doc can also be manually called, keep the auto-detection
logic if the parameter was not specified. On such case, emit
a warning if sphinx-build can't be found at PATH.

I ended using a suggestion from Joe for using a more readable
regex, instead of using a complex one with a hidden group like:

	m/^(\d+)\.(\d+)(?:\.?(\d+)?)/

in order to get the optional <patch> argument.

Thanks-to: Joe Perches <joe@perches.com>
Suggested-by: default avatarJonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
      93351d41