提交 d2802d07 编写于 作者: S Steven Rostedt (Red Hat) 提交者: Steven Rostedt

tracing: Compare to 1 instead of zero for is_signed_type()

The formats of the trace events show if the type of a event field
is signed or not via a macro called is_signed_type(). This does
a trick with the type and compares a -1 to zero after typecasting
to the tested type. If it returns true, it's signed, otherwise
its not. But this unfortunately triggers a warning by gcc:

  warning: comparison of unsigned expression < 0 is always false

As we know it is always false (that's why we do it), this is a
false warning. Luckily for us, the comparison works with a 1 as
well, without giving the warning.

Convert the check to compare (type)-1 < (type)0 to (type)-1 < (type)1
to determine if the type is signed or not.

Link: http://lkml.kernel.org/r/CAErSpo4YXcY9fuOKWYGDkddJwk68kmZTohsmVB6QvrhjboOh1Q@mail.gmail.comReported-by: NBjorn Helgaas <bhelgaas@google.com>
Reported-by: NGary Hade <garyhade@us.ibm.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
上级 c192c835
......@@ -333,7 +333,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
extern int trace_add_event_call(struct ftrace_event_call *call);
extern void trace_remove_event_call(struct ftrace_event_call *call);
#define is_signed_type(type) (((type)(-1)) < (type)0)
#define is_signed_type(type) (((type)(-1)) < (type)1)
int trace_set_clr_event(const char *system, const char *event, int set);
......
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