[dm-devel] [PATCH v2 14/29] libmultipath: add libmp_dm_exit()

[Benjamin Marzinski]

On Fri, Oct 16, 2020 at 12:44:46PM +0200, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>
> 
> This function prepares for calling dm_lib_exit() on program exit.
> It undoes changes to libdm internals done by libmultipath.
> It doesn't call dm_lib_exit(), as the caller may want to keep
> libdm active.
> 
Reviewed-by: Benjamin Marzinski <bmarzins at redhat.com>
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>  libmultipath/config.c    |  1 +
>  libmultipath/config.h    |  2 ++
>  libmultipath/devmapper.c | 15 +++++++++++++++
>  libmultipath/devmapper.h |  1 +
>  4 files changed, 19 insertions(+)
> 
> diff --git a/libmultipath/config.c b/libmultipath/config.c
> index f74417c..b9cb413 100644
> --- a/libmultipath/config.c
> +++ b/libmultipath/config.c
> @@ -60,6 +60,7 @@ int libmultipath_init(void)
>  static void _libmultipath_exit(void)
>  {
>  	libmultipath_exit_called = true;
> +	libmp_dm_exit();
>  	udev_unref(udev);
>  }
>  
> diff --git a/libmultipath/config.h b/libmultipath/config.h
> index f478df7..5d46035 100644
> --- a/libmultipath/config.h
> +++ b/libmultipath/config.h
> @@ -271,6 +271,8 @@ int libmultipath_init(void);
>   *
>   * This function un-initializes libmultipath data structures.
>   * It is recommended to call this function at program exit.
> + * If the application also calls dm_lib_exit(), it should do so
> + * after libmultipath_exit().
>   *
>   * Calls to libmultipath_init() after libmultipath_exit() will fail
>   * (in other words, libmultipath can't be re-initialized).
> diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
> index 2e3ae8a..a8e0611 100644
> --- a/libmultipath/devmapper.c
> +++ b/libmultipath/devmapper.c
> @@ -333,6 +333,20 @@ void libmp_udev_set_sync_support(int on)
>  	libmp_dm_udev_sync = !!on;
>  }
>  
> +static bool libmp_dm_init_called;
> +void libmp_dm_exit(void)
> +{
> +	if (!libmp_dm_init_called)
> +		return;
> +
> +	/* switch back to default libdm logging */
> +	dm_log_init(NULL);
> +#ifdef LIBDM_API_HOLD_CONTROL
> +	/* make sure control fd is closed in dm_lib_release() */
> +	dm_hold_control_dev(0);
> +#endif
> +}
> +
>  static void libmp_dm_init(void)
>  {
>  	struct config *conf;
> @@ -349,6 +363,7 @@ static void libmp_dm_init(void)
>  	dm_hold_control_dev(1);
>  #endif
>  	dm_udev_set_sync_support(libmp_dm_udev_sync);
> +	libmp_dm_init_called = true;
>  }
>  
>  static void _do_skip_libmp_dm_init(void)
> diff --git a/libmultipath/devmapper.h b/libmultipath/devmapper.h
> index 158057e..ecf2e66 100644
> --- a/libmultipath/devmapper.h
> +++ b/libmultipath/devmapper.h
> @@ -35,6 +35,7 @@ enum {
>  
>  int dm_prereq(unsigned int *v);
>  void skip_libmp_dm_init(void);
> +void libmp_dm_exit(void);
>  void libmp_udev_set_sync_support(int on);
>  struct dm_task *libmp_dm_task_create(int task);
>  int dm_simplecmd_flush (int, const char *, uint16_t);
> -- 
> 2.28.0