When CONFIG_OPTIMIZE_INLINING is enabled for s390, I see this warning: arch/s390/mm/fault.c:127:15: warning: 'asce' may be used uninitialized in this function [-Wmaybe-uninitialized] switch (asce & _ASCE_TYPE_MASK) { arch/s390/mm/fault.c:177:16: note: 'asce' was declared here unsigned long asce; ^~~~ If get_fault_type() is not inlined, the compiler cannot deduce that all the possible paths in the 'switch' statement are covered. Of course, we could mark get_fault_type() as __always_inline to get back the original behavior, but I do not think it sensible to force inlining just for the purpose of suppressing the warning. Since this is just a matter of warning, I want to keep as much room for compiler optimization as possible. I added unreachable() to teach the compiler that the 'default' label is unreachable. I got rid of the 'inline' marker. Even without the 'inline' hint, the compiler inlines functions based on its inlining heuristic. Fixes: 9012d011660e ("compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING") Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> --- arch/s390/mm/fault.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index c220399ae196..91ce03fd0c84 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -85,7 +85,7 @@ static inline int notify_page_fault(struct pt_regs *regs) * Find out which address space caused the exception. * Access register mode is impossible, ignore space == 3. */ -static inline enum fault_type get_fault_type(struct pt_regs *regs) +static enum fault_type get_fault_type(struct pt_regs *regs) { unsigned long trans_exc_code; @@ -211,6 +211,8 @@ static void dump_fault_info(struct pt_regs *regs) asce = S390_lowcore.kernel_asce; pr_cont("kernel "); break; + default: + unreachable(); } pr_cont("ASCE.\n"); dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); -- 2.17.1