Rename the kld_unload event handler to kld_unload_try, and add a new

kld_unload event handler which gets invoked after a linker file has been
successfully unloaded. The kld_unload and kld_load event handlers are now
invoked with the shared linker lock held, while kld_unload_try is invoked
with the lock exclusively held.

Convert hwpmc(4) to use these event handlers instead of having
kern_kldload() and kern_kldunload() invoke hwpmc(4) hooks whenever files are
loaded or unloaded. This has no functional effect, but simplifes the linker
code somewhat.

Reviewed by:	jhb

3 files changed, 9 insertions, 9 deletions

diff --git a/sys/cddl/dev/dtrace/dtrace_load.c b/sys/cddl/dev/dtrace/dtrace_load.c
index f37d593..05436fe 100644
--- a/sys/cddl/dev/dtrace/dtrace_load.c
+++ b/sys/cddl/dev/dtrace/dtrace_load.c
@@ -59,8 +59,8 @@ dtrace_load(void *dummy)
 	/* Register callbacks for linker file load and unload events. */
 	dtrace_kld_load_tag = EVENTHANDLER_REGISTER(kld_load,
 	    dtrace_kld_load, NULL, EVENTHANDLER_PRI_ANY);
-	dtrace_kld_unload_tag = EVENTHANDLER_REGISTER(kld_unload,
-	    dtrace_kld_unload, NULL, EVENTHANDLER_PRI_ANY);
+	dtrace_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try,
+	    dtrace_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY);
 
 	/*
 	 * Initialise the mutexes without 'witness' because the dtrace
diff --git a/sys/cddl/dev/dtrace/dtrace_unload.c b/sys/cddl/dev/dtrace/dtrace_unload.c
index 9e37114..e9bd53c 100644
--- a/sys/cddl/dev/dtrace/dtrace_unload.c
+++ b/sys/cddl/dev/dtrace/dtrace_unload.c
@@ -68,7 +68,7 @@ dtrace_unload()
 
 	dtrace_provider = NULL;
 	EVENTHANDLER_DEREGISTER(kld_load, dtrace_kld_load_tag);
-	EVENTHANDLER_DEREGISTER(kld_unload, dtrace_kld_unload_tag);
+	EVENTHANDLER_DEREGISTER(kld_unload_try, dtrace_kld_unload_try_tag);
 
 	if ((state = dtrace_anon_grab()) != NULL) {
 		/*
diff --git a/sys/cddl/dev/sdt/sdt.c b/sys/cddl/dev/sdt/sdt.c
index b65d1ad..41d3610 100644
--- a/sys/cddl/dev/sdt/sdt.c
+++ b/sys/cddl/dev/sdt/sdt.c
@@ -59,7 +59,7 @@ static int	sdt_unload(void *);
 static void	sdt_create_provider(struct sdt_provider *);
 static void	sdt_create_probe(struct sdt_probe *);
 static void	sdt_kld_load(void *, struct linker_file *);
-static void	sdt_kld_unload(void *, struct linker_file *, int *);
+static void	sdt_kld_unload_try(void *, struct linker_file *, int *);
 
 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
 
@@ -95,7 +95,7 @@ static struct cdev	*sdt_cdev;
 static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
 
 eventhandler_tag	sdt_kld_load_tag;
-eventhandler_tag	sdt_kld_unload_tag;
+eventhandler_tag	sdt_kld_unload_try_tag;
 
 static void
 sdt_create_provider(struct sdt_provider *prov)
@@ -264,7 +264,7 @@ sdt_kld_load(void *arg __unused, struct linker_file *lf)
 }
 
 static void
-sdt_kld_unload(void *arg __unused, struct linker_file *lf, int *error __unused)
+sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error __unused)
 {
 	struct sdt_provider *prov, **curr, **begin, **end, *tmp;
 
@@ -319,8 +319,8 @@ sdt_load(void *arg __unused)
 
 	sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL,
 	    EVENTHANDLER_PRI_ANY);
-	sdt_kld_unload_tag = EVENTHANDLER_REGISTER(kld_unload, sdt_kld_unload,
-	    NULL, EVENTHANDLER_PRI_ANY);
+	sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try,
+	    sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY);
 
 	/* Pick up probes from the kernel and already-loaded linker files. */
 	linker_file_foreach(sdt_linker_file_cb, NULL);
@@ -332,7 +332,7 @@ sdt_unload(void *arg __unused)
 	struct sdt_provider *prov, *tmp;
 
 	EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
-	EVENTHANDLER_DEREGISTER(kld_unload, sdt_kld_unload_tag);
+	EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
 
 	sdt_probe_func = sdt_probe_stub;