[PATCH 10/18] libmultipath: checkers: add support for async checker

If a checker shared library contains a symbol "libcheck_async_func",
use this as a callback for the async checker functions, and do not
read any other symbols from the .so file except the message table.

Checkers can provide a symbol async_context_size that will cause
the async_checker code to reserve extra space in runner_data for
the checker to use, and a symbol async_init() for initializing
this private context.

Only emc_clariion will use the latter functionality.

Signed-off-by: Martin Wilck <[email protected]>
---
 libmultipath/checkers.c           | 51 +++++++++++++++++++++----------
 libmultipath/libmultipath.version |  2 +-
 2 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/libmultipath/checkers.c b/libmultipath/checkers.c
index 3a1663f..2f20b25 100644
--- a/libmultipath/checkers.c
+++ b/libmultipath/checkers.c
@@ -101,6 +101,18 @@ void reset_checker_classes(void)
 	}
 }
 
+static struct checker_class *add_async_checker_class(struct checker_class *c)
+{
+	c->init = async_check_init;
+	c->check = async_check_check;
+	c->need_wait = async_check_need_wait;
+	c->pending = async_check_pending;
+	c->free = async_check_free;
+
+	list_add(&c->node, &checkers);
+	return c;
+}
+
 static struct checker_class *add_checker_class(const char *name)
 {
 	char libname[LIB_CHECKER_NAMELEN];
@@ -129,6 +141,29 @@ static struct checker_class *add_checker_class(const char *name)
 				errstr);
 		goto out;
 	}
+
+	c->msgtable_size = 0;
+	c->msgtable = dlsym(c->handle, "libcheck_msgtable");
+
+	if (c->msgtable != NULL) {
+		const char **p;
+
+		for (p = c->msgtable;
+		     *p && (p - c->msgtable) < CHECKER_MSGTABLE_SIZE; p++)
+			/* nothing */;
+
+		c->msgtable_size = p - c->msgtable;
+	} else
+		c->msgtable_size = 0;
+	condlog(3, "checker %s: message table size = %d", c->name,
+		c->msgtable_size);
+
+	c->async_func = (int (*)(struct runner_data *))
+		dlsym(c->handle, "libcheck_async_func");
+	errstr = dlerror();
+	if (c->async_func)
+		return add_async_checker_class(c);
+
 	c->check = (int (*)(struct checker *)) dlsym(c->handle, "libcheck_check");
 	errstr = dlerror();
 	if (errstr != NULL)
@@ -158,22 +193,6 @@ static struct checker_class *add_checker_class(const char *name)
 	if (!c->free)
 		goto out;
 
-	c->msgtable_size = 0;
-	c->msgtable = dlsym(c->handle, "libcheck_msgtable");
-
-	if (c->msgtable != NULL) {
-		const char **p;
-
-		for (p = c->msgtable;
-		     *p && (p - c->msgtable) < CHECKER_MSGTABLE_SIZE; p++)
-			/* nothing */;
-
-		c->msgtable_size = p - c->msgtable;
-	} else
-		c->msgtable_size = 0;
-	condlog(3, "checker %s: message table size = %d",
-		c->name, c->msgtable_size);
-
 done:
 	c->sync = 1;
 	list_add(&c->node, &checkers);
diff --git a/libmultipath/libmultipath.version b/libmultipath/libmultipath.version
index 78fa2d4..5e8dbda 100644
--- a/libmultipath/libmultipath.version
+++ b/libmultipath/libmultipath.version
@@ -43,7 +43,7 @@ LIBMPATHCOMMON_1.0.0 {
 	put_multipath_config;
 };
 
-LIBMULTIPATH_32.0.0 {
+LIBMULTIPATH_33.0.0 {
 global:
 	/* symbols referenced by multipath and multipathd */
 	add_foreign;
-- 
2.54.0