[dm-devel] [PATCH 06/11] libmultipath: checkers/prio: allow non-lazy .so loading

[Benjamin Marzinski]

On Thu, Sep 24, 2020 at 03:36:39PM +0200, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>
> 
> If compiled with -DLOAD_ALL_SHARED_LIBS, all known prioritizers
> and checkers will be loaded immediately on startup. This is useful
> for determining symbol usage (start executables with LD_BIND_NOW=1).

It seems like you could avoid having to remember to update these arrays
when new checker or prio DSOs are added by just scanning multipath_dir
for all the existing checkers/prioritizers.  On the flip side, I'm not
sure that's worth the extra work, and this way has the benefit of
warning if any expected chekers/priotitizers are missing, so

Reviewed-by: Benjamin Marzinski <bmarzins at redhat.com>

> ---
>  libmultipath/checkers.c | 17 +++++++++++++++++
>  libmultipath/prio.c     | 22 ++++++++++++++++++++++
>  2 files changed, 39 insertions(+)
> 
> diff --git a/libmultipath/checkers.c b/libmultipath/checkers.c
> index f7ddd53..18b1f5e 100644
> --- a/libmultipath/checkers.c
> +++ b/libmultipath/checkers.c
> @@ -7,6 +7,7 @@
>  #include "debug.h"
>  #include "checkers.h"
>  #include "vector.h"
> +#include "util.h"
>  
>  struct checker_class {
>  	struct list_head node;
> @@ -375,7 +376,23 @@ void checker_get(const char *multipath_dir, struct checker *dst,
>  
>  int init_checkers(const char *multipath_dir)
>  {
> +#ifdef LOAD_ALL_SHARED_LIBS
> +	static const char *const all_checkers[] = {
> +		DIRECTIO,
> +		TUR,
> +		HP_SW,
> +		RDAC,
> +		EMC_CLARIION,
> +		READSECTOR0,
> +		CCISS_TUR,
> +	};
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(all_checkers); i++)
> +		add_checker_class(multipath_dir, all_checkers[i]);
> +#else
>  	if (!add_checker_class(multipath_dir, DEFAULT_CHECKER))
>  		return 1;
> +#endif
>  	return 0;
>  }
> diff --git a/libmultipath/prio.c b/libmultipath/prio.c
> index 3a718ba..c92bde7 100644
> --- a/libmultipath/prio.c
> +++ b/libmultipath/prio.c
> @@ -20,8 +20,30 @@ unsigned int get_prio_timeout(unsigned int timeout_ms,
>  
>  int init_prio (const char *multipath_dir)
>  {
> +#ifdef LOAD_ALL_SHARED_LIBS
> +	static const char *const all_prios[] = {
> +		PRIO_ALUA,
> +		PRIO_CONST,
> +		PRIO_DATACORE,
> +		PRIO_EMC,
> +		PRIO_HDS,
> +		PRIO_HP_SW,
> +		PRIO_ONTAP,
> +		PRIO_RANDOM,
> +		PRIO_RDAC,
> +		PRIO_WEIGHTED_PATH,
> +		PRIO_SYSFS,
> +		PRIO_PATH_LATENCY,
> +		PRIO_ANA,
> +	};
> +	unsigned int i;
> +
> +	for  (i = 0; i < ARRAY_SIZE(all_prios); i++)
> +		add_prio(multipath_dir, all_prios[i]);
> +#else
>  	if (!add_prio(multipath_dir, DEFAULT_PRIO))
>  		return 1;
> +#endif
>  	return 0;
>  }
>  
> -- 
> 2.28.0