| Message ID | 20190325125807.1437049-1-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | 3771b0fe9dfc3801eac0142d1af6ba94dee83c6c |
| Headers | show |
| Series | lockdep: avoid bogus clang warning | expand |
On Mon, 25 Mar 2019 13:57:57 +0100 Arnd Bergmann <arnd@arndb.de> wrote: > When lockdep is enabled, and -Wuninitialized warnings are enabled, > clang produces a silly warning for every file we compile: > > In file included from kernel/sched/fair.c:23: > kernel/sched/sched.h:1094:15: error: variable 'cookie' is uninitialized when used here [-Werror,-Wuninitialized] > rf->cookie = lockdep_pin_lock(&rq->lock); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~ Sad it warns as struct pin_cookie is of size zero. But hey. > include/linux/lockdep.h:474:60: note: expanded from macro 'lockdep_pin_lock' > #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) > ^~~~~~ > kernel/sched/sched.h:1094:15: note: variable 'cookie' is declared here > include/linux/lockdep.h:474:34: note: expanded from macro 'lockdep_pin_lock' > #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) > ^ > As the 'struct pin_cookie' structure is empty in this configuration, > there is no need to initialize it for correctness, but it also > does not hurt to set it to an empty structure, so do that to > avoid the warning. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > include/linux/lockdep.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h > index 79c3873d58ac..31d7549933eb 100644 > --- a/include/linux/lockdep.h > +++ b/include/linux/lockdep.h > @@ -471,7 +471,7 @@ struct pin_cookie { }; > > #define NIL_COOKIE (struct pin_cookie){ } > > -#define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) > +#define lockdep_pin_lock(l) ({ struct pin_cookie cookie = {}; cookie; }) Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> -- Steve > #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0) > #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0) >
On Mon, Mar 25, 2019 at 01:57:57PM +0100, Arnd Bergmann wrote: > When lockdep is enabled, and -Wuninitialized warnings are enabled, > clang produces a silly warning for every file we compile: > > In file included from kernel/sched/fair.c:23: > kernel/sched/sched.h:1094:15: error: variable 'cookie' is uninitialized when used here [-Werror,-Wuninitialized] > rf->cookie = lockdep_pin_lock(&rq->lock); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~ > include/linux/lockdep.h:474:60: note: expanded from macro 'lockdep_pin_lock' > #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) > ^~~~~~ > kernel/sched/sched.h:1094:15: note: variable 'cookie' is declared here > include/linux/lockdep.h:474:34: note: expanded from macro 'lockdep_pin_lock' > #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) > ^ > As the 'struct pin_cookie' structure is empty in this configuration, > there is no need to initialize it for correctness, but it also > does not hurt to set it to an empty structure, so do that to > avoid the warning. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > include/linux/lockdep.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h > index 79c3873d58ac..31d7549933eb 100644 > --- a/include/linux/lockdep.h > +++ b/include/linux/lockdep.h > @@ -471,7 +471,7 @@ struct pin_cookie { }; > > #define NIL_COOKIE (struct pin_cookie){ } > > -#define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) > +#define lockdep_pin_lock(l) ({ struct pin_cookie cookie = {}; cookie; }) > #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0) > #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0) Acked-by: Will Deacon <will.deacon@arm.com> Will
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 79c3873d58ac..31d7549933eb 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -471,7 +471,7 @@ struct pin_cookie { }; #define NIL_COOKIE (struct pin_cookie){ } -#define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) +#define lockdep_pin_lock(l) ({ struct pin_cookie cookie = {}; cookie; }) #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0) #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0)
When lockdep is enabled, and -Wuninitialized warnings are enabled, clang produces a silly warning for every file we compile: In file included from kernel/sched/fair.c:23: kernel/sched/sched.h:1094:15: error: variable 'cookie' is uninitialized when used here [-Werror,-Wuninitialized] rf->cookie = lockdep_pin_lock(&rq->lock); ^~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/lockdep.h:474:60: note: expanded from macro 'lockdep_pin_lock' #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) ^~~~~~ kernel/sched/sched.h:1094:15: note: variable 'cookie' is declared here include/linux/lockdep.h:474:34: note: expanded from macro 'lockdep_pin_lock' #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; }) ^ As the 'struct pin_cookie' structure is empty in this configuration, there is no need to initialize it for correctness, but it also does not hurt to set it to an empty structure, so do that to avoid the warning. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/lockdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.20.0