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- Convert the per-eventhandler list mutex to a lockmgr lock so that it can

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be safely held across an eventhandler function call.
- Fix an instance of the head of an eventhandler list being read without
  the lock being held.
- Break down and use a SYSINIT at the new SI_SUB_EVENTHANDLER to initialize
  the eventhandler global mutex and the eventhandler list of lists rather
  than using a non-MP safe initialization during the first call to
  eventhandler_register().
- Add in a KASSERT() to eventhandler_register() to ensure that we don't try
  to register an eventhandler before things have been initialized.
This commit is contained in:
John Baldwin 2000-12-12 04:01:35 +00:00
parent 18f619abce
commit 06592dd188
3 changed files with 29 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
sys/kern/subr_eventhandler.c
View File

@ -29,6 +29,7 @@
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
@ -45,6 +46,19 @@ struct eventhandler_entry_generic
void (* func)(void);
};
/*
* Initialize the eventhandler mutex and list.
*/
static void
eventhandler_init(void *dummy __unused)
{
TAILQ_INIT(&eventhandler_lists);
mtx_init(&eventhandler_mutex, "eventhandler", MTX_DEF);
eventhandler_lists_initted = 1;
}
SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init,
NULL)
/*
* Insertion is O(n) due to the priority scan, but optimises to O(1)
* if all priorities are identical.
@ -56,12 +70,7 @@ eventhandler_register(struct eventhandler_list *list, char *name,
struct eventhandler_entry_generic *eg;
struct eventhandler_entry *ep;
/* avoid the need for a SYSINIT just to init the list */
if (!eventhandler_lists_initted) {
TAILQ_INIT(&eventhandler_lists);
mtx_init(&eventhandler_mutex, "eventhandler", MTX_DEF);
eventhandler_lists_initted = 1;
}
KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
/* lock the eventhandler lists */
mtx_enter(&eventhandler_mutex, MTX_DEF);
@ -86,7 +95,7 @@ eventhandler_register(struct eventhandler_list *list, char *name,
}
if (!(list->el_flags & EHE_INITTED)) {
TAILQ_INIT(&list->el_entries);
mtx_init(&list->el_mutex, name, MTX_DEF);
lockinit(&list->el_lock, PZERO, name, 0, 0);
list->el_flags = EHE_INITTED;
}
@ -101,7 +110,7 @@ eventhandler_register(struct eventhandler_list *list, char *name,
eg->ee.ee_priority = priority;
/* sort it into the list */
mtx_enter(&list->el_mutex, MTX_DEF);
lockmgr(&list->el_lock, LK_EXCLUSIVE, NULL, CURPROC);
for (ep = TAILQ_FIRST(&list->el_entries);
ep != NULL;
ep = TAILQ_NEXT(ep, ee_link)) {
@ -112,7 +121,7 @@ eventhandler_register(struct eventhandler_list *list, char *name,
}
if (ep == NULL)
TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
mtx_exit(&list->el_mutex, MTX_DEF);
lockmgr(&list->el_lock, LK_RELEASE, NULL, CURPROC);
mtx_exit(&eventhandler_mutex, MTX_DEF);
return(&eg->ee);
}
@ -123,7 +132,7 @@ eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
struct eventhandler_entry *ep = tag;
/* XXX insert diagnostic check here? */
mtx_enter(&list->el_mutex, MTX_DEF);
lockmgr(&list->el_lock, LK_EXCLUSIVE, NULL, CURPROC);
if (ep != NULL) {
/* remove just this entry */
TAILQ_REMOVE(&list->el_entries, ep, ee_link);
@ -136,7 +145,7 @@ eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
free(ep, M_EVENTHANDLER);
}
}
mtx_exit(&list->el_mutex, MTX_DEF);
lockmgr(&list->el_lock, LK_RELEASE, NULL, CURPROC);
}
struct eventhandler_list *

18
sys/sys/eventhandler.h
View File

@ -30,7 +30,7 @@
#define SYS_EVENTHANDLER_H
#include <sys/queue.h>
#include <sys/mutex.h>
#include <sys/lock.h>
struct eventhandler_entry
{
@ -44,7 +44,7 @@ struct eventhandler_list
char *el_name;
int el_flags;
#define EHE_INITTED (1<<0)
struct mtx el_mutex;
struct lock el_lock;
TAILQ_ENTRY(eventhandler_list) el_link;
TAILQ_HEAD(,eventhandler_entry) el_entries;
};
@ -77,18 +77,18 @@ struct __hack
#define EVENTHANDLER_FAST_INVOKE(name, args...) \
do { \
struct eventhandler_list *_el = &Xeventhandler_list_ ## name ; \
struct eventhandler_entry *_ep = TAILQ_FIRST(&(_el->el_entries)); \
struct eventhandler_entry *_en; \
struct eventhandler_entry *_ep, *_en; \
\
if (_el->el_flags & EHE_INITTED) { \
lockmgr(&_el->el_lock, LK_EXCLUSIVE, NULL, CURPROC); \
_ep = TAILQ_FIRST(&(_el->el_entries)); \
while (_ep != NULL) { \
mtx_enter(&_el->el_mutex, MTX_DEF); \
_en = TAILQ_NEXT(_ep, ee_link); \
mtx_exit(&_el->el_mutex, MTX_DEF); \
((struct eventhandler_entry_ ## name *)_ep)->eh_func(_ep->ee_arg , \
## args); \
_ep = _en; \
} \
lockmgr(&_el->el_lock, LK_RELEASE, NULL, CURPROC); \
} \
} while (0)
@ -120,17 +120,15 @@ do { \
\
if (((_el = eventhandler_find_list(#name)) != NULL) && \
(_el->el_flags & EHE_INITTED)) { \
mtx_enter(&_el->el_mutex, MTX_DEF); \
lockmgr(&_el->el_lock, LK_EXCLUSIVE, NULL, CURPROC); \
_ep = TAILQ_FIRST(&(_el->el_entries)); \
mtx_exit(&_el->el_mutex, MTX_DEF); \
while (_ep != NULL) { \
mtx_enter(&_el->el_mutex, MTX_DEF); \
_en = TAILQ_NEXT(_ep, ee_link); \
mtx_exit(&_el->el_mutex, MTX_DEF); \
((struct eventhandler_entry_ ## name *)_ep)->eh_func(_ep->ee_arg , \
## args); \
_ep = _en; \
} \
lockmgr(&_el->el_lock, LK_RELEASE, NULL, CURPROC); \
} \
} while (0)

1
sys/sys/kernel.h
View File

@ -114,6 +114,7 @@ enum sysinit_sub_id {
SI_SUB_KMEM = 0x1800000, /* kernel memory*/
SI_SUB_KVM_RSRC = 0x1A00000, /* kvm operational limits*/
SI_SUB_LOCK = 0x1B00000, /* lockmgr locks */
SI_SUB_EVENTHANDLER = 0x1C00000, /* eventhandler init */
SI_SUB_CPU = 0x2000000, /* CPU resource(s)*/
SI_SUB_KLD = 0x2100000, /* KLD and module setup */
SI_SUB_INTRINSIC = 0x2200000, /* proc 0*/