When building with -Wsometimes-uninitialized, Clang warns: net/atm/resources.c:256:6: warning: variable 'number' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] net/atm/resources.c:212:7: warning: variable 'iobuf_len' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
Clang won't realize that compat is 0 when CONFIG_COMPAT is not set until the constant folding stage, which happens after this semantic analysis. Use IS_ENABLED instead so that the zero is present at the semantic analysis stage, which eliminates this warning. Link: https://github.com/ClangBuiltLinux/linux/issues/386 Signed-off-by: Nathan Chancellor <natechancel...@gmail.com> --- I don't think this looks the greatest because of the IS_ENABLED + #ifdef but the only other solution I could think of looks way uglier to me: https://gist.github.com/74650e9139f704a5435f82fc80d59969 net/atm/resources.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/net/atm/resources.c b/net/atm/resources.c index bada395ecdb1..3e9f6391319e 100644 --- a/net/atm/resources.c +++ b/net/atm/resources.c @@ -203,13 +203,9 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg, int compat) int __user *sioc_len; int __user *iobuf_len; -#ifndef CONFIG_COMPAT - compat = 0; /* Just so the compiler _knows_ */ -#endif - switch (cmd) { case ATM_GETNAMES: - if (compat) { + if (IS_ENABLED(CONFIG_COMPAT) && compat) { #ifdef CONFIG_COMPAT struct compat_atm_iobuf __user *ciobuf = arg; compat_uptr_t cbuf; @@ -253,7 +249,7 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg, int compat) break; } - if (compat) { + if (IS_ENABLED(CONFIG_COMPAT) && compat) { #ifdef CONFIG_COMPAT struct compat_atmif_sioc __user *csioc = arg; compat_uptr_t carg; -- 2.21.0
