On Sun, Dec 05, 2021 at 09:49:51AM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > Back in mid-2021, Kees and Gustavo rammed into the kernel a bunch of > static checker "improvements" that redefined '/* fallthrough */' > comments for switch statements as a macro that virtualizes either that > same comment, a do-while loop, or a compiler __attribute__. This was > necessary to work around the poor decision-making of the clang, gcc, and > C language standard authors, who collectively came up with four mutually > incompatible ways to document a lack of branching in a code flow. > > Having received ZERO HELP porting this to userspace, Eric and I > foolishly dumped that crap into linux.h, which was a poor decision > because we keep forgetting that linux.h is exported as a userspace > header. This has now caused downstream regressions in Debian[1] and > will probably cause more problems in the other distros. > > Move it to platform_defs.h since that's not shipped publicly and leave a > warning to anyone else who dare modify linux.h. > > [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1000974 > > Fixes: df9c7d8d ("xfs: Fix fall-through warnings for Clang") > Cc: 1000974@xxxxxxxxxxxxxxx, gustavoars@xxxxxxxxxx, keescook@xxxxxxxxxxxx > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > --- > include/linux.h | 20 ++------------------ > include/platform_defs.h.in | 21 +++++++++++++++++++++ > 2 files changed, 23 insertions(+), 18 deletions(-) > > diff --git a/include/linux.h b/include/linux.h > index 24650228..054117aa 100644 > --- a/include/linux.h > +++ b/include/linux.h > @@ -360,24 +360,8 @@ fsmap_advance( > #endif /* HAVE_MAP_SYNC */ > > /* > - * Add the pseudo keyword 'fallthrough' so case statement blocks > - * must end with any of these keywords: > - * break; > - * fallthrough; > - * continue; > - * goto <label>; > - * return [expression]; > - * > - * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes > + * Reminder: anything added to this file will be compiled into downstream > + * userspace projects! This comment belongs at the top of the file before all the includes, not at the end of it. Otherwise looks ok for a quick fix. Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx> But I have to wonder - why is this file even exported to userspace? It's mostly the xfsprogs source build wrapper stuff for linux - there's no public API in it except for xfsctl().... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
