To differentiate between long arrays and cpumasks, the __cpumask() field was created. Part of the TRACE_EVENT() macros test if the type is signed or not by using the is_signed_type() macro. The __cpumask() field used the __dynamic_array() helper but because cpumask_t is a structure, it could not be used in the is_signed_type() macro as that would fail to build, so instead it passed in the pointer to cpumask_t. Unfortunately, that creates in the format file: field:__data_loc cpumask_t *[] mask; offset:36; size:4; signed:0; Which looks like an array of pointers to cpumask_t and not a cpumask_t type, which is misleading to user space parsers. Douglas Raillard pointed out that the "[]" are also misleading, as cpumask_t is not an array. Since cpumask() hasn't been created yet, and the parsers currently fail on it (but will still produce the raw output), make it be: field:__data_loc cpumask_t mask; offset:36; size:4; signed:0; Which is the correct type of the field. Then the parsers can be updated to handle this. Link: https://lore.kernel.org/lkml/6dda5e1d-9416-b55e-88f3-31d148bc925f@arm.com/ Link: https://lore.kernel.org/linux-trace-kernel/20221212193814.0e3f1e43@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Valentin Schneider <vschneid@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Fixes: 8230f27b1ccc ("tracing: Add __cpumask to denote a trace event field that is a cpumask_t") Reported-by: Douglas Raillard <douglas.raillard@arm.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.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 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.
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