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Don't call malloc with M_WAITOK while holding a mutex.

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alfred 2001-03-09 18:40:34 +00:00
parent 80d8e16746
commit 219bcef498
1 changed files with 21 additions and 22 deletions
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43
sys/kern/kern_resource.c
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@ -69,7 +69,6 @@ static struct mtx uihashtbl_mtx;
static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash; /* size of hash table - 1 */
static struct uidinfo *uicreate __P((uid_t uid));
static struct uidinfo *uilookup __P((uid_t uid));
/*
@ -732,25 +731,6 @@ uilookup(uid)
return (uip);
}
/*
* Create a uidinfo struct for the parameter uid.
* uihashtbl_mtx must be locked.
*/
static struct uidinfo *
uicreate(uid)
uid_t uid;
{
struct uidinfo *uip;
mtx_assert(&uihashtbl_mtx, MA_OWNED);
MALLOC(uip, struct uidinfo *, sizeof(*uip), M_UIDINFO,
M_WAITOK | M_ZERO);
LIST_INSERT_HEAD(UIHASH(uid), uip, ui_hash);
uip->ui_uid = uid;
mtx_init(&uip->ui_mtx, "uidinfo struct", MTX_DEF);
return (uip);
}
/*
* Find or allocate a struct uidinfo for a particular uid.
* Increase refcount on uidinfo struct returned.
@ -764,8 +744,27 @@ uifind(uid)
mtx_lock(&uihashtbl_mtx);
uip = uilookup(uid);
if (uip == NULL)
uip = uicreate(uid);
if (uip == NULL) {
struct uidinfo *old_uip;
mtx_unlock(&uihashtbl_mtx);
uip = malloc(sizeof(*uip), M_UIDINFO, M_WAITOK | M_ZERO);
mtx_lock(&uihashtbl_mtx);
/*
* There's a chance someone created our uidinfo while we
* were in malloc and not holding the lock, so we have to
* make sure we don't insert a duplicate uidinfo
*/
if ((old_uip = uilookup(uid)) != NULL) {
/* someone else beat us to it */
free(uip, M_UIDINFO);
uip = old_uip;
} else {
mtx_init(&uip->ui_mtx, "uidinfo struct", MTX_DEF);
uip->ui_uid = uid;
LIST_INSERT_HEAD(UIHASH(uid), uip, ui_hash);
}
}
uihold(uip);
mtx_unlock(&uihashtbl_mtx);
return (uip);