From 03ad5aa4c1f93b5b86c67c9db3cb7754da597a10 Mon Sep 17 00:00:00 2001 From: Andriy Gapon Date: Fri, 1 Sep 2017 18:02:53 +0000 Subject: [PATCH] 8569 problem with inline functions in abd.h illumos/illumos-gate@37e84ab74e939caf52150fc3352081786ecc0c29 https://github.com/illumos/illumos-gate/commit/37e84ab74e939caf52150fc3352081786ecc0c29 https://www.illumos.org/issues/8569 C [C99] has peculiar rules for inline functions that are different from the C++ rules. Unlike C++ where inline is "fire and forget", in C a programmer must pay attention to the function's storage class / visibility. The main problem is with the case where a compiler decides to not inline a call to the function declared as inline. Some relevant links: - http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka15831.html - http://www.drdobbs.com/the-new-c-inline-functions/184401540 The summary is that either the inline functions should be declared 'static inline' or one of the compilation units (.c files) must provide a callable externally visible function definition. In the former case, the compiler would automatically create a local non-inlined function instance in every compilation unit where it's needed. In the latter case the single external definition is used to satisfy any non-inlined calls in all compilation units. As things stand right now, we can get an undefined reference error under certain combinations of compilers and compiler options. For example, this is what I get on FreeBSD when compiling with clang 4.0.0 and -O1: In function `abd_free': /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c:385: undefined reference to `abd_is_linear' So, there are two alternatives. Either to qualify each inline function in abd.h with static storage class. Or to add declarations like the following to abd.c: extern inline boolean_t abd_is_linear(abd_t *abd); Both work. I am not sure which one would be more consistent with the illumos development rules. Reviewed by: Matt Ahrens Approved by: Robert Mustacchi Author: Andriy Gapon --- uts/common/fs/zfs/abd.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/uts/common/fs/zfs/abd.c b/uts/common/fs/zfs/abd.c index 932ba800ed5f..4d7b2cb56a21 100644 --- a/uts/common/fs/zfs/abd.c +++ b/uts/common/fs/zfs/abd.c @@ -157,6 +157,13 @@ extern vmem_t *zio_alloc_arena; kmem_cache_t *abd_chunk_cache; static kstat_t *abd_ksp; +extern inline boolean_t abd_is_linear(abd_t *abd); +extern inline void abd_copy(abd_t *dabd, abd_t *sabd, size_t size); +extern inline void abd_copy_from_buf(abd_t *abd, const void *buf, size_t size); +extern inline void abd_copy_to_buf(void* buf, abd_t *abd, size_t size); +extern inline int abd_cmp_buf(abd_t *abd, const void *buf, size_t size); +extern inline void abd_zero(abd_t *abd, size_t size); + static void * abd_alloc_chunk() {