Bart Van Assche
33580d667b
As one can see in include/trace/stages/stage4_event_fields.h, the
implementation of __field() uses the is_signed_type() macro. As one can
see in commit dcf8e5633e ("tracing: Define the is_signed_type() macro
once"), there has been an attempt to not make is_signed_type() trigger
sparse warnings for bitwise types.
Despite that change, sparse complains when passing a bitwise type to
is_signed_type(). The reason is that in its definition below, an
inequality comparison will be made against bitwise types, which are random
collections of bits (the casts to bitwise types themselves are
semantically valid and not problematic):
#define is_signed_type(type) (((type)(-1)) < (__force type)1)
So, as a workaround, follow the example of <trace/events/initcall.h> and
suppress the following sparse warnings by changing __field() into
__field_struct() that doesn't use is_signed_type():
fs/nilfs2/segment.c: note: in included file (through
include/trace/trace_events.h, include/trace/define_trace.h,
include/trace/events/nilfs2.h):
./include/trace/events/nilfs2.h:191:1: warning: cast to restricted
blk_opf_t
./include/trace/events/nilfs2.h:191:1: warning: restricted blk_opf_t
degrades to integer
./include/trace/events/nilfs2.h:191:1: warning: restricted blk_opf_t
degrades to integer
[konishi.ryusuke: describe the reason for the warnings per Linus's explanation]
Link: https://lkml.kernel.org/r/20240507222041.4876-1-konishi.ryusuke@gmail.com
Link: https://lkml.kernel.org/r/20240507142454.3344-1-konishi.ryusuke@gmail.com
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401092241.I4mm9OWl-lkp@intel.com/
Reported-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Closes: https://lore.kernel.org/all/20240430080019.4242-2-konishi.ryusuke@gmail.com/
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.