From 735b7636d1a88e85eeef607a8179a114618bc5a0 Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Fri, 26 Jan 2024 07:28:53 -0800 Subject: [PATCH] lkdtm/bugs: In lkdtm_HUNG_TASK() use BUG(), not BUG_ON(1) In commit edb6538da3df ("lkdtm/bugs: Adjust lkdtm_HUNG_TASK() to avoid tail call optimization") we marked lkdtm_HUNG_TASK() as __noreturn. The compiler gets unhappy if it thinks a __noreturn function might return, so there's a BUG_ON(1) at the end. Any human can see that the function won't return and the compiler can figure that out too. Except when it can't. The MIPS architecture defines HAVE_ARCH_BUG_ON and defines its own version of BUG_ON(). The MIPS version of BUG_ON() is not a macro but is instead an inline function. Apparently this prevents the compiler from realizing that the condition to BUG_ON() is constant and that the function will never return. Let's change the BUG_ON(1) to just BUG(), which it should have been to begin with. The only reason I used BUG_ON(1) to begin with was because I was used to using WARN_ON(1) when writing test code and WARN() and BUG() are oddly inconsistent in this manner. :-/ Fixes: edb6538da3df ("lkdtm/bugs: Adjust lkdtm_HUNG_TASK() to avoid tail call optimization") Signed-off-by: Douglas Anderson Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202401262204.wUFKRYZF-lkp@intel.com/ Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/20240126072852.1.Ib065e528a8620474a72f15baa2feead1f3d89865@changeid Signed-off-by: Kees Cook --- drivers/misc/lkdtm/bugs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index d1222d3eda2f1..b92767d6bdd24 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -298,7 +298,7 @@ static void __noreturn lkdtm_HUNG_TASK(void) { set_current_state(TASK_UNINTERRUPTIBLE); schedule(); - BUG_ON(1); + BUG(); } static volatile unsigned int huge = INT_MAX - 2; -- 2.30.2