From 0d24f1b7cc65ee73ea8d04e0d10f77a7cb7a83f3 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Tue, 13 Dec 2022 11:35:28 -0700 Subject: [PATCH] padata: Mark padata_work_init() as __ref When building arm64 allmodconfig + ThinLTO with clang and a proposed modpost update to account for -ffuncton-sections, the following warning appears: WARNING: modpost: vmlinux.o: section mismatch in reference: padata_work_init (section: .text.padata_work_init) -> padata_mt_helper (section: .init.text) WARNING: modpost: vmlinux.o: section mismatch in reference: padata_work_init (section: .text.padata_work_init) -> padata_mt_helper (section: .init.text) LLVM has optimized padata_work_init() to include the address of padata_mt_helper() directly because it inlined the other call to padata_work_init() with padata_parallel_worker(), meaning the remaining uses of padata_work_init() use padata_mt_helper() as the work_fn argument. This optimization causes modpost to complain since padata_work_init() is not __init, whereas padata_mt_helper() is. Since padata_work_init() is only called from __init code when padata_mt_helper() is passed as the work_fn argument, mark padata_work_init() as __ref, which makes it clear to modpost that this scenario is okay. Suggested-by: Daniel Jordan Signed-off-by: Nathan Chancellor Acked-by: Daniel Jordan Signed-off-by: Masahiro Yamada --- kernel/padata.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/padata.c b/kernel/padata.c index e5819bb8bd1d..d175cc000453 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -83,8 +83,16 @@ static struct padata_work *padata_work_alloc(void) return pw; } -static void padata_work_init(struct padata_work *pw, work_func_t work_fn, - void *data, int flags) +/* + * This function is marked __ref because this function may be optimized in such + * a way that it directly refers to work_fn's address, which causes modpost to + * complain when work_fn is marked __init. This scenario was observed with clang + * LTO, where padata_work_init() was optimized to refer directly to + * padata_mt_helper() because the calls to padata_work_init() with other work_fn + * values were eliminated or inlined. + */ +static void __ref padata_work_init(struct padata_work *pw, work_func_t work_fn, + void *data, int flags) { if (flags & PADATA_WORK_ONSTACK) INIT_WORK_ONSTACK(&pw->pw_work, work_fn);