Using a __bitwise type in a tracing __field() definition triggers four sparse warnings in stage 4 of expanding the TRACE_EVENT() macro. These warnings are triggered by the is_signed_type() macro implementation. Since there is no known way of checking signedness of a bitwise type without triggering sparse warnings, disable signedness checking when verifying code with sparse. Note: work is in progress to improve sparse but has not yet landed. See also "[PATCH 0/5] allow -1 and compares in bitwise types" (https://lore.kernel.org/all/20220627190540.13358-1-luc.vanoostenryck@xxxxxxxxx/ ). Suggested-by: Christoph Hellwig <hch@xxxxxx> Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> --- include/linux/trace_events.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index e6e95a9f07a5..e43f0f37ef27 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -814,7 +814,19 @@ extern int trace_add_event_call(struct trace_event_call *call); extern int trace_remove_event_call(struct trace_event_call *call); extern int trace_event_get_offsets(struct trace_event_call *call); +/* + * There is no known way to check signedness of __bitwise types without + * triggering a sparse warning. Hence the #ifdef __CHECKER__. + * + * Since there is another definition of is_signed_type() in <linux/overflow.h>, + * undefine is_signed_type() before redefining it. + */ +#undef is_signed_type +#ifdef __CHECKER__ +#define is_signed_type(type) 0 +#else #define is_signed_type(type) (((type)(-1)) < (type)1) +#endif int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set); int trace_set_clr_event(const char *system, const char *event, int set);
|