On Thu, 2025-05-08 at 11:38 -0700, Alexei Starovoitov wrote:
On Thu, May 8, 2025 at 4:38 AM Ilya Leoshkevich
<iii@xxxxxxxxxxxxx>
wrote:
clang-21 complains about unused expressions in a few
progs.
Fix by explicitly casting the respective expressions to
void.
...
if (val & _Q_LOCKED_MASK)
- smp_cond_load_acquire_label(&lock-
locked,
!VAL,
release_err);
+ (void)smp_cond_load_acquire_label(&lock-
locked,
!VAL, release_err);
Hmm. I'm on clang-21 too and I don't see them.
What warnings do you see ?
In file included from progs/arena_spin_lock.c:7:
progs/bpf_arena_spin_lock.h:305:1756: error: expression
result
unused
[-Werror,-Wunused-value]
305 | ({ typeof(_Generic((*&lock->locked), char: (char)0,
unsigned
char : (unsigned char)0, signed char : (signed char)0,
unsigned
short :
(unsigned short)0, signed short : (signed short)0, unsigned
int :
(unsigned int)0, signed int : (signed int)0, unsigned long :
(unsigned
long)0, signed long : (signed long)0, unsigned long long :
(unsigned
long long)0, signed long long : (signed long long)0, default:
(typeof(*&lock->locked))0)) __val = ({ typeof(&lock->locked)
__ptr
=
(&lock->locked); typeof(_Generic((*(&lock->locked)), char:
(char)0,
unsigned char : (unsigned char)0, signed char : (signed
char)0,
unsigned short : (unsigned short)0, signed short : (signed
short)0,
unsigned int : (unsigned int)0, signed int : (signed int)0,
unsigned
long : (unsigned long)0, signed long : (signed long)0,
unsigned
long
long : (unsigned long long)0, signed long long : (signed long
long)0,
default: (typeof(*(&lock->locked)))0)) VAL; for (;;) { VAL =
(typeof(_Generic((*(&lock->locked)), char: (char)0, unsigned
char :
(unsigned char)0, signed char : (signed char)0, unsigned
short :
(unsigned short)0, signed short : (signed short)0, unsigned
int :
(unsigned int)0, signed int : (signed int)0, unsigned long :
(unsigned
long)0, signed long : (signed long)0, unsigned long long :
(unsigned
long long)0, signed long long : (signed long long)0, default:
(typeof(*(&lock->locked)))0)))(*(volatile typeof(*__ptr)
*)&(*__ptr));
if (!VAL) break; ({ __label__ l_break, l_continue; asm
volatile
goto("may_goto %l[l_break]" :::: l_break); goto l_continue;
l_break:
goto release_err; l_continue:; }); ({}); } (typeof(*(&lock-
locked)))VAL; }); ({ ({ if (!CONFIG_X86_64) ({ unsigned
long
__val;
__sync_fetch_and_add(&__val, 0); }); else asm volatile("" :::
"memory"); }); }); (typeof(*(&lock->locked)))__val; });
|
^ ~~~~~
1 error generated.
