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Add event handlers for module load and unload events. The load handlers are

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called after the module has been loaded, and the unload handlers are called
before the module is unloaded. Moreover, the module unload handlers may
return an error to prevent the unload from proceeding.

Reviewed by:	avg
MFC after:	2 weeks
This commit is contained in:
markj 2013-08-13 03:07:49 +00:00
parent c063aad382
commit 80dd3f5e73
3 changed files with 22 additions and 3 deletions
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8
share/man/man9/EVENTHANDLER.9
View File

@ -23,7 +23,7 @@
.\" SUCH DAMAGE.
.\" $FreeBSD$
.\"
.Dd May 11, 2012
.Dd August 1, 2013
.Dt EVENTHANDLER 9
.Os
.Sh NAME
@ -199,6 +199,12 @@ Callbacks invoked when a new network interface appears.
Callbacks invoked when a network interface is taken down.
.It Vt bpf_track
Callbacks invoked when a BPF listener attaches to/detaches from network interface.
.It Vt mod_load
Callbacks invoked after a module has been loaded.
.It Vt mod_unload
Callbacks invoked before a module is about to be unloaded.
These callbacks may be used to return an error and prevent the unload from
proceeding.
.It Vt power_profile_change
Callbacks invoked when the power profile of the system changes.
.It Vt process_exec

10
sys/kern/kern_linker.c
View File

@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/linker.h>
#include <sys/eventhandler.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/libkern.h>
@ -1046,6 +1047,9 @@ kern_kldload(struct thread *td, const char *file, int *fileid)
lf->userrefs++;
if (fileid != NULL)
*fileid = lf->id;
EVENTHANDLER_INVOKE(mod_load, lf);
#ifdef HWPMC_HOOKS
KLD_DOWNGRADE();
pkm.pm_file = lf->filename;
@ -1101,8 +1105,10 @@ kern_kldunload(struct thread *td, int fileid, int flags)
if (lf) {
KLD_DPF(FILE, ("kldunload: lf->userrefs=%d\n", lf->userrefs));
/* Check if there are DTrace probes enabled on this file. */
if (lf->nenabled > 0) {
EVENTHANDLER_INVOKE(mod_unload, lf, &error);
if (error != 0)
error = EBUSY;
else if (lf->nenabled > 0) {
printf("kldunload: attempt to unload file that has"
" DTrace probes enabled\n");
error = EBUSY;

7
sys/sys/eventhandler.h
View File

@ -266,4 +266,11 @@ EVENTHANDLER_DECLARE(nmbclusters_change, uma_zone_chfn);
EVENTHANDLER_DECLARE(nmbufs_change, uma_zone_chfn);
EVENTHANDLER_DECLARE(maxsockets_change, uma_zone_chfn);
/* Module load and unload events */
struct linker_file;
typedef void (*mod_load_fn)(void *, struct linker_file *);
typedef void (*mod_unload_fn)(void *, struct linker_file *, int *);
EVENTHANDLER_DECLARE(mod_load, mod_load_fn);
EVENTHANDLER_DECLARE(mod_unload, mod_unload_fn);
#endif /* SYS_EVENTHANDLER_H */