7604256cec
The __string() helper macro of the TRACE_EVENT() macro is used to
determine how much of the ring buffer needs to be allocated to fit the
given source string. Some trace events have a string that is dependent on
another variable that could be NULL, and in those cases the string is
passed in to be NULL.
The __string() macro can handle being passed in a NULL pointer for which
it will turn it into "(null)". It does that with:
strlen((src) ? (const char *)(src) : "(null)") + 1
But if src itself has the same conditional type it can confuse the
compiler. That is:
__string(r ? dev(r)->name : NULL)
Would turn into:
strlen((r ? dev(r)->name : NULL) ? (r ? dev(r)->name : NULL) : "(null)" + 1
For which the compiler thinks that NULL is being passed to strlen() and
gives this kind of warning:
./include/trace/stages/stage5_get_offsets.h:50:21: warning: argument 1 null where non-null expected [-Wnonnull]
50 | strlen((src) ? (const char *)(src) : "(null)") + 1)
Instead, create a static inline function that takes the src string and
will return the string if it is not NULL and will return "(null)" if it
is. This will then make the strlen() line:
strlen(__string_src(src)) + 1
Where the compiler can see that strlen() will not end up with NULL and
does not warn about it.
Note that this depends on commit
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| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
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 ReStructured Text 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.