Date: Sat, 25 Nov 2000 04:17:47 -0800 From: Alfred Perlstein <bright@wintelcom.net> To: smp@freebsd.org Subject: uidinfo patches, review please. Message-ID: <20001125041747.I8051@fw.wintelcom.net>
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Protect the uidinfo structures.
My only concern is that I must now include sys/mutex.h in
sys/resourcevar.h, I didn't notice any userland utils using
this file, I'm going to try to do a buildworld.
A kernel with this patch boots and seems to run multiuser
fine.
Index: kern/kern_resource.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_resource.c,v
retrieving revision 1.65
diff -u -r1.65 kern_resource.c
--- kern/kern_resource.c 2000/11/22 07:41:58 1.65
+++ kern/kern_resource.c 2000/11/25 12:16:02
@@ -64,6 +64,7 @@
static MALLOC_DEFINE(M_UIDINFO, "uidinfo", "uidinfo structures");
#define UIHASH(uid) (&uihashtbl[(uid) & uihash])
+static struct mtx uidhash_mtx;
static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash; /* size of hash table - 1 */
@@ -663,9 +664,15 @@
void
uihashinit()
{
+
uihashtbl = hashinit(maxproc / 16, M_UIDINFO, &uihash);
+ mtx_init(&uidhash_mtx, "uidinfo hash", MTX_DEF);
}
+/*
+ * lookup a uidinfo struct for the parameter uid.
+ * uidhash_mtx must be locked.
+ */
static struct uidinfo *
uilookup(uid)
uid_t uid;
@@ -673,6 +680,7 @@
struct uihashhead *uipp;
struct uidinfo *uip;
+ mtx_assert(&uidhash_mtx, MA_OWNED);
uipp = UIHASH(uid);
LIST_FOREACH(uip, uipp, ui_hash)
if (uip->ui_uid == uid)
@@ -681,43 +689,42 @@
return (uip);
}
+/*
+ * Create a uidinfo struct for the parameter uid.
+ * uidhash_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(&uidhash_mtx, MA_OWNED);
+ MALLOC(uip, struct uidinfo *, sizeof(*uip), M_UIDINFO, M_WAITOK);
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
+ */
struct uidinfo *
uifind(uid)
uid_t uid;
{
struct uidinfo *uip;
+ mtx_enter(&uidhash_mtx, MTX_DEF);
uip = uilookup(uid);
if (uip == NULL)
uip = uicreate(uid);
- uip->ui_ref++;
+ uihold(uip);
+ mtx_exit(&uidhash_mtx, MTX_DEF);
return (uip);
}
@@ -726,6 +733,8 @@
struct uidinfo *uip;
{
+ mtx_enter(&uidhash_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. */
@@ -735,9 +744,13 @@
printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
uip->ui_uid, uip->ui_proccnt);
LIST_REMOVE(uip, ui_hash);
+ mtx_destroy(&uip->ui_mtx);
+ mtx_exit(&uidhash_mtx, MTX_DEF);
FREE(uip, M_UIDINFO);
return (1);
}
+ mtx_exit(&uip->ui_mtx, MTX_DEF);
+ mtx_exit(&uidhash_mtx, MTX_DEF);
return (0);
}
@@ -751,12 +764,17 @@
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 +791,14 @@
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 +806,6 @@
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);
}
Index: sys/resourcevar.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/resourcevar.h,v
retrieving revision 1.17
diff -u -r1.17 resourcevar.h
--- sys/resourcevar.h 2000/09/05 22:11:12 1.17
+++ sys/resourcevar.h 2000/11/25 12:16:03
@@ -40,6 +40,9 @@
#include <sys/resource.h>
#include <sys/queue.h>
+#include <sys/mutex.h> /* XXX */
+
+
/*
* Kernel per-process accounting / statistics
* (not necessarily resident except when running).
@@ -90,10 +93,17 @@
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));
--
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."
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