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lkdtm/bugs: Do not confuse the clang/objtool with busy wait loop

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Since commit eb972eab07 ("lkdtm/bugs: Add cases for BUG and PANIC
occurring in hardirq context"), building with clang for x86_64 results
in the following warnings:

vmlinux.o: warning: objtool: lkdtm_PANIC_IN_HARDIRQ(): unexpected end of section .text.lkdtm_PANIC_IN_HARDIRQ
vmlinux.o: warning: objtool: lkdtm_BUG_IN_HARDIRQ(): unexpected end of section .text.lkdtm_BUG_IN_HARDIRQ

caused by busy "while (wait_for_...);" loops. Add READ_ONCE() and
cpu_relax() to better indicate the intention and avoid any unwanted
compiler optimisations.

Fixes: eb972eab07 ("lkdtm/bugs: Add cases for BUG and PANIC occurring in hardirq context")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512190111.jxFSqxUH-lkp@intel.com/
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas
2025-12-19 15:09:09 +00:00
parent 98a97bf415
commit f4ea8e05f2
1 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/misc/lkdtm/bugs.c
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@@ -120,8 +120,8 @@ static void lkdtm_PANIC_IN_HARDIRQ(void)
CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD);
while (wait_for_panic)
;
while (READ_ONCE(wait_for_panic))
cpu_relax();
hrtimer_cancel(&timer);
}
@@ -150,8 +150,8 @@ static void lkdtm_BUG_IN_HARDIRQ(void)
CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD);
while (wait_for_bug)
;
while (READ_ONCE(wait_for_bug))
cpu_relax();
hrtimer_cancel(&timer);
}