On Tue, Apr 15, 2025 at 4:06 AM Louis Chauvet <louis.chau...@bootlin.com> wrote:
>
>
>
> Le 02/04/2025 à 19:41, Jim Cromie a écrit :
> > The Xe driver's XE_IOCTL_DBG macro calls drm_dbg() from inside an if
> > (expression). This breaks when CONFIG_DRM_USE_DYNAMIC_DEBUG=y because
> > the invoked macro has a do-while-0 wrapper.
> >
> > if (cond && (drm_dbg("expr-form"),1)) {
> > ... do some more stuff
> > }
> >
> > Fix for this usage by changing __dynamic_func_call_cls{,_no_desc}
> > macros into expressions, by replacing the do-while-0s with a ({ })
> > wrapper. In the common usage, the trailing ';' converts the
> > expression into a statement.
> >
> > drm_dbg("statement form");
> >
> > Signed-off-by: Jim Cromie <jim.cro...@gmail.com>
> > ---
> > ---
> > include/linux/dynamic_debug.h | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> > index ce221a702f84..2d87cca27544 100644
> > --- a/include/linux/dynamic_debug.h
> > +++ b/include/linux/dynamic_debug.h
> > @@ -337,20 +337,20 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
> > * (|_cls): adds in _DPRINT_CLASS_DFLT as needed
> > * (|_no_desc): former gets callsite descriptor as 1st arg (for
> > prdbgs)
> > */
> > -#define __dynamic_func_call_cls(id, cls, fmt, func, ...) do { \
> > - DEFINE_DYNAMIC_DEBUG_METADATA_CLS((id), cls, fmt); \
> > +#define __dynamic_func_call_cls(id, cls, fmt, func, ...) ({ \
> > + DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt); \
>
> You remove the protection around id here.
>
> > if (DYNAMIC_DEBUG_BRANCH(id)) \
> > - func(&id, ##__VA_ARGS__); \
> > -} while (0)
> > + func(&(id), ##__VA_ARGS__); \
>
> But you add the protection here.
>
> I think in macro it is better to be defensive, so I expect to have ()
> everywhere (except places where it breaks the compilation).
>
yeah, Im a bit inconsistent.
defensive parens are almost never a compilation err.
I'll go thru the macros again
> > +})
> > #define __dynamic_func_call(id, fmt, func, ...)
> > \
> > __dynamic_func_call_cls(id, _DPRINTK_CLASS_DFLT, fmt, \
> > func, ##__VA_ARGS__)
> >
> > -#define __dynamic_func_call_cls_no_desc(id, cls, fmt, func, ...) do {
> > \
> > +#define __dynamic_func_call_cls_no_desc(id, cls, fmt, func, ...) ({ \
> > DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt); \
> > if (DYNAMIC_DEBUG_BRANCH(id)) \
> > func(__VA_ARGS__); \
> > -} while (0)
> > +})
> > #define __dynamic_func_call_no_desc(id, fmt, func, ...)
> > \
> > __dynamic_func_call_cls_no_desc(id, _DPRINTK_CLASS_DFLT, \
> > fmt, func, ##__VA_ARGS__)
>
> --
> Louis Chauvet, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
>
