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8569 problem with inline functions in abd.h

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illumos/illumos-gate@37e84ab74e
37e84ab74e

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 <mahrens@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Andriy Gapon <avg@FreeBSD.org>
This commit is contained in:
Andriy Gapon 2017-09-01 18:02:53 +00:00
parent e08e3c87ce
commit 03ad5aa4c1
1 changed files with 7 additions and 0 deletions
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7
uts/common/fs/zfs/abd.c
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@ -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()
{