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Make uidinfo subsystem mpsafe

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use a mutex lock when looking up/deleting entries on the hashlist
use a mutex lock on each uidinfo when updating fields

make uifree() a void function rather than 'int' since no one cares

allocate uidinfo structs with the M_ZERO flag and don't explicitly initialize
them

Assisted by: eivind, jhb, jakeb
This commit is contained in:
Alfred Perlstein 2000-11-26 12:08:17 +00:00
parent cca0db7e7e
commit 9c19bcddf0
2 changed files with 55 additions and 24 deletions
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67
sys/kern/kern_resource.c
View File

@ -64,6 +64,7 @@ int dosetrlimit __P((struct proc *p, u_int which, struct rlimit *limp));
static MALLOC_DEFINE(M_UIDINFO, "uidinfo", "uidinfo structures");
#define UIHASH(uid) (&uihashtbl[(uid) & uihash])
static struct mtx uihashtbl_mtx;
static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash; /* size of hash table - 1 */
@ -663,9 +664,15 @@ limcopy(lim)
void
uihashinit()
{
uihashtbl = hashinit(maxproc / 16, M_UIDINFO, &uihash);
mtx_init(&uihashtbl_mtx, "uidinfo hash", MTX_DEF);
}
/*
* lookup a uidinfo struct for the parameter uid.
* uihashtbl_mtx must be locked.
*/
static struct uidinfo *
uilookup(uid)
uid_t uid;
@ -673,6 +680,7 @@ uilookup(uid)
struct uihashhead *uipp;
struct uidinfo *uip;
mtx_assert(&uihashtbl_mtx, MA_OWNED);
uipp = UIHASH(uid);
LIST_FOREACH(uip, uipp, ui_hash)
if (uip->ui_uid == uid)
@ -681,51 +689,54 @@ 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, *norace;
struct uidinfo *uip;
MALLOC(uip, struct uidinfo *, sizeof(*uip), M_UIDINFO, M_NOWAIT);
if (uip == NULL) {
MALLOC(uip, struct uidinfo *, sizeof(*uip), M_UIDINFO, M_WAITOK);
/*
* if we M_WAITOK we must look afterwards or risk
* redundant entries
*/
norace = uilookup(uid);
if (norace != NULL) {
FREE(uip, M_UIDINFO);
return (norace);
}
}
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;
uip->ui_proccnt = 0;
uip->ui_sbsize = 0;
uip->ui_ref = 0;
mtx_init(&uip->ui_mtx, "uidinfo struct", MTX_DEF);
return (uip);
}
/*
* find or allocate a struct uidinfo for a particular uid
* increases refcount on uidinfo struct returned.
* uifree() should be called on a struct uidinfo when released.
*/
struct uidinfo *
uifind(uid)
uid_t uid;
{
struct uidinfo *uip;
mtx_enter(&uihashtbl_mtx, MTX_DEF);
uip = uilookup(uid);
if (uip == NULL)
uip = uicreate(uid);
uip->ui_ref++;
uihold(uip);
mtx_exit(&uihashtbl_mtx, MTX_DEF);
return (uip);
}
int
/*
* subtract one from the refcount in the struct uidinfo, if 0 free it
*/
void
uifree(uip)
struct uidinfo *uip;
{
mtx_enter(&uihashtbl_mtx, MTX_DEF);
mtx_enter(&uip->ui_mtx, MTX_DEF);
if (--uip->ui_ref == 0) {
if (uip->ui_sbsize != 0)
/* XXX no %qd in kernel. Truncate. */
@ -735,10 +746,14 @@ uifree(uip)
printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
uip->ui_uid, uip->ui_proccnt);
LIST_REMOVE(uip, ui_hash);
mtx_exit(&uihashtbl_mtx, MTX_DEF);
mtx_destroy(&uip->ui_mtx);
FREE(uip, M_UIDINFO);
return (1);
return;
}
return (0);
mtx_exit(&uip->ui_mtx, MTX_DEF);
mtx_exit(&uihashtbl_mtx, MTX_DEF);
return;
}
/*
@ -751,12 +766,17 @@ chgproccnt(uip, diff, max)
int diff;
int max;
{
mtx_enter(&uip->ui_mtx, MTX_DEF);
/* don't allow them to exceed max, but allow subtraction */
if (diff > 0 && uip->ui_proccnt + diff > max && max != 0)
if (diff > 0 && uip->ui_proccnt + diff > max && max != 0) {
mtx_exit(&uip->ui_mtx, MTX_DEF);
return (0);
}
uip->ui_proccnt += diff;
if (uip->ui_proccnt < 0)
printf("negative proccnt for uid = %d\n", uip->ui_uid);
mtx_exit(&uip->ui_mtx, MTX_DEF);
return (1);
}
@ -773,11 +793,13 @@ chgsbsize(uip, hiwat, to, max)
rlim_t new;
int s;
mtx_enter(&uip->ui_mtx, MTX_DEF);
s = splnet();
new = uip->ui_sbsize + to - *hiwat;
/* don't allow them to exceed max, but allow subtraction */
if (to > *hiwat && new > max) {
splx(s);
mtx_exit(&uip->ui_mtx, MTX_DEF);
return (0);
}
uip->ui_sbsize = new;
@ -785,5 +807,6 @@ chgsbsize(uip, hiwat, to, max)
if (uip->ui_sbsize < 0)
printf("negative sbsize for uid = %d\n", uip->ui_uid);
splx(s);
mtx_exit(&uip->ui_mtx, MTX_DEF);
return (1);
}

12
sys/sys/resourcevar.h
View File

@ -39,6 +39,7 @@
#include <sys/resource.h>
#include <sys/queue.h>
#include <sys/mutex.h> /* XXX */
/*
* Kernel per-process accounting / statistics
@ -90,10 +91,17 @@ struct uidinfo {
long ui_proccnt; /* number of processes */
uid_t ui_uid; /* uid */
u_short ui_ref; /* reference count */
struct mtx ui_mtx; /* protect counts */
};
#ifdef _KERNEL
#define uihold(uip) (uip)->ui_ref++
#define uihold(uip) \
do { \
mtx_enter(&(uip)->ui_mtx, MTX_DEF); \
(uip)->ui_ref++; \
mtx_exit(&(uip)->ui_mtx, MTX_DEF); \
} while(0)
struct proc;
void addupc_intr __P((struct proc *p, u_long pc, u_int ticks));
@ -110,7 +118,7 @@ void ruadd __P((struct rusage *ru, struct rusage *ru2));
int suswintr __P((void *base, int word));
struct uidinfo
*uifind __P((uid_t uid));
int uifree __P((struct uidinfo *uip));
void uifree __P((struct uidinfo *uip));
void uihashinit __P((void));
#endif