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init / exit function ordering

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The vlib init function subsystem now supports a mix of procedural and
formally-specified ordering constraints. We should eliminate procedural
knowledge wherever possible.

The following schemes are *roughly* equivalent:

static clib_error_t *init_runs_first (vlib_main_t *vm)
{
   clib_error_t *error;

   ... do some stuff...

   if ((error = vlib_call_init_function (init_runs_next)))
     return error;
   ...
}
VLIB_INIT_FUNCTION (init_runs_first);

and

static clib_error_t *init_runs_first (vlib_main_t *vm)
{
   ... do some stuff...
}
VLIB_INIT_FUNCTION (init_runs_first) =
{
    .runs_before = VLIB_INITS("init_runs_next"),
};

The first form will [most likely] call "init_runs_next" on the
spot. The second form means that "init_runs_first" runs before
"init_runs_next," possibly much earlier in the sequence.

Please DO NOT construct sets of init functions where A before B
actually means A *right before* B. It's not necessary - simply combine
A and B - and it leads to hugely annoying debugging exercises when
trying to switch from ad-hoc procedural ordering constraints to formal
ordering constraints.

Change-Id: I5e4353503bf43b4acb11a45fb33c79a5ade8426c
Signed-off-by: Dave Barach <dave@barachs.net>
This commit is contained in:
Dave Barach
2019-05-14 18:01:44 -04:00
committed by Florin Coras
parent c1f93067ed
commit f8d50682cd
62 changed files with 959 additions and 476 deletions
Download Patch File Download Diff File Expand all files Collapse all files

91
src/vlib/init.h
View File

@ -54,6 +54,10 @@ typedef struct _vlib_init_function_list_elt
{
struct _vlib_init_function_list_elt *next_init_function;
vlib_init_function_t *f;
char *name;
char **runs_before;
char **runs_after;
char **init_order;
} _vlib_init_function_list_elt_t;
/* Configuration functions: called with configuration input just before
@ -116,48 +120,54 @@ typedef struct vlib_config_function_runtime_t
be called from other modules to resolve init function depend. */
#ifndef CLIB_MARCH_VARIANT
#define VLIB_DECLARE_INIT_FUNCTION(x, tag) \
vlib_init_function_t * _VLIB_INIT_FUNCTION_SYMBOL (x, tag) = x; \
static void __vlib_add_##tag##_function_##x (void) \
__attribute__((__constructor__)) ; \
static void __vlib_add_##tag##_function_##x (void) \
{ \
vlib_main_t * vm = vlib_get_main(); \
static _vlib_init_function_list_elt_t _vlib_init_function; \
_vlib_init_function.next_init_function \
= vm->tag##_function_registrations; \
vm->tag##_function_registrations = &_vlib_init_function; \
_vlib_init_function.f = &x; \
} \
static void __vlib_rm_##tag##_function_##x (void) \
__attribute__((__destructor__)) ; \
static void __vlib_rm_##tag##_function_##x (void) \
{ \
vlib_main_t * vm = vlib_get_main(); \
_vlib_init_function_list_elt_t *next; \
if (vm->tag##_function_registrations->f == &x) \
{ \
vm->tag##_function_registrations = \
vm->tag##_function_registrations->next_init_function; \
return; \
} \
next = vm->tag##_function_registrations; \
while (next->next_init_function) \
{ \
if (next->next_init_function->f == &x) \
{ \
next->next_init_function = \
next->next_init_function->next_init_function; \
return; \
} \
next = next->next_init_function; \
} \
}
#define VLIB_DECLARE_INIT_FUNCTION(x, tag) \
vlib_init_function_t * _VLIB_INIT_FUNCTION_SYMBOL (x, tag) = x; \
static void __vlib_add_##tag##_function_##x (void) \
__attribute__((__constructor__)) ; \
static _vlib_init_function_list_elt_t _vlib_init_function_##tag_##x; \
static void __vlib_add_##tag##_function_##x (void) \
{ \
vlib_main_t * vm = vlib_get_main(); \
_vlib_init_function_##tag_##x.next_init_function \
= vm->tag##_function_registrations; \
vm->tag##_function_registrations = &_vlib_init_function_##tag_##x; \
_vlib_init_function_##tag_##x.f = &x; \
_vlib_init_function_##tag_##x.name = #x; \
} \
static void __vlib_rm_##tag##_function_##x (void) \
__attribute__((__destructor__)) ; \
static void __vlib_rm_##tag##_function_##x (void) \
{ \
vlib_main_t * vm = vlib_get_main(); \
_vlib_init_function_list_elt_t *this, *prev; \
this = vm->tag##_function_registrations; \
if (this == 0) \
return; \
if (this->f == &x) \
{ \
vm->tag##_function_registrations = this->next_init_function; \
return; \
} \
prev = this; \
this = this->next_init_function; \
while (this) \
{ \
if (this->f == &x) \
{ \
prev->next_init_function = \
this->next_init_function; \
return; \
} \
prev = this; \
this = this->next_init_function; \
} \
} \
static _vlib_init_function_list_elt_t _vlib_init_function_##tag_##x
#else
/* create unused pointer to silence compiler warnings and get whole
function optimized out */
#define VLIB_DECLARE_INIT_FUNCTION(x, tag) \
static __clib_unused void * __clib_unused_##tag##_##x = x;
static __clib_unused void * __clib_unused_##tag##_##x = x
#endif
#define VLIB_INIT_FUNCTION(x) VLIB_DECLARE_INIT_FUNCTION(x,init)
@ -316,8 +326,8 @@ clib_error_t *vlib_call_all_main_loop_enter_functions (struct vlib_main_t
*vm);
clib_error_t *vlib_call_all_main_loop_exit_functions (struct vlib_main_t *vm);
clib_error_t *vlib_call_init_exit_functions (struct vlib_main_t *vm,
_vlib_init_function_list_elt_t *
head, int call_once);
_vlib_init_function_list_elt_t **
headp, int call_once);
#define foreach_vlib_module_reference \
_ (node_cli) \
@ -327,6 +337,7 @@ clib_error_t *vlib_call_init_exit_functions (struct vlib_main_t *vm,
#define _(x) void vlib_##x##_reference (void);
foreach_vlib_module_reference
#undef _
#define VLIB_INITS(...) (char*[]) { __VA_ARGS__, 0}
#endif /* included_vlib_init_h */
/*
* fd.io coding-style-patch-verification: ON