Author: mjg
Date: Mon Oct 27 20:20:05 2014
New Revision: 273746
URL: https://svnweb.freebsd.org/changeset/base/273746
Log:
Tidy up functions related to uidinfo management.
- reference found uidinfo in uilookup
- reduce nesting by handling shorter cases first
Modified:
head/sys/kern/kern_resource.c
Modified: head/sys/kern/kern_resource.c
==============================================================================
--- head/sys/kern/kern_resource.c Mon Oct 27 20:18:30 2014
(r273745)
+++ head/sys/kern/kern_resource.c Mon Oct 27 20:20:05 2014
(r273746)
@@ -1215,6 +1215,7 @@ uihashinit()
/*
* Look up a uidinfo struct for the parameter uid.
* uihashtbl_lock must be locked.
+ * Increase refcount on uidinfo struct returned.
*/
static struct uidinfo *
uilookup(uid_t uid)
@@ -1225,49 +1226,52 @@ uilookup(uid_t uid)
rw_assert(&uihashtbl_lock, RA_LOCKED);
uipp = UIHASH(uid);
LIST_FOREACH(uip, uipp, ui_hash)
- if (uip->ui_uid == uid)
+ if (uip->ui_uid == uid) {
+ uihold(uip);
break;
+ }
return (uip);
}
/*
* Find or allocate a struct uidinfo for a particular uid.
- * Increase refcount on uidinfo struct returned.
+ * Returns with uidinfo struct referenced.
* uifree() should be called on a struct uidinfo when released.
*/
struct uidinfo *
uifind(uid_t uid)
{
- struct uidinfo *old_uip, *uip;
+ struct uidinfo *new_uip, *uip;
rw_rlock(&uihashtbl_lock);
uip = uilookup(uid);
- if (uip == NULL) {
- rw_runlock(&uihashtbl_lock);
- uip = malloc(sizeof(*uip), M_UIDINFO, M_WAITOK | M_ZERO);
- racct_create(&uip->ui_racct);
- rw_wlock(&uihashtbl_lock);
- /*
- * 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. */
- racct_destroy(&uip->ui_racct);
- free(uip, M_UIDINFO);
- uip = old_uip;
- } else {
- refcount_init(&uip->ui_ref, 0);
- uip->ui_uid = uid;
- mtx_init(&uip->ui_vmsize_mtx, "ui_vmsize", NULL,
- MTX_DEF);
- LIST_INSERT_HEAD(UIHASH(uid), uip, ui_hash);
- }
+ rw_runlock(&uihashtbl_lock);
+ if (uip != NULL)
+ return (uip);
+
+ new_uip = malloc(sizeof(*new_uip), M_UIDINFO, M_WAITOK | M_ZERO);
+ racct_create(&new_uip->ui_racct);
+ refcount_init(&new_uip->ui_ref, 1);
+ new_uip->ui_uid = uid;
+ mtx_init(&new_uip->ui_vmsize_mtx, "ui_vmsize", NULL, MTX_DEF);
+
+ rw_wlock(&uihashtbl_lock);
+ /*
+ * 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 ((uip = uilookup(uid)) == NULL) {
+ LIST_INSERT_HEAD(UIHASH(uid), new_uip, ui_hash);
+ rw_wunlock(&uihashtbl_lock);
+ uip = new_uip;
+ } else {
+ rw_wunlock(&uihashtbl_lock);
+ racct_destroy(&new_uip->ui_racct);
+ mtx_destroy(&new_uip->ui_vmsize_mtx);
+ free(new_uip, M_UIDINFO);
}
- uihold(uip);
- rw_unlock(&uihashtbl_lock);
return (uip);
}
@@ -1308,28 +1312,26 @@ uifree(struct uidinfo *uip)
/* Prepare for suboptimal case. */
rw_wlock(&uihashtbl_lock);
- if (refcount_release(&uip->ui_ref)) {
- racct_destroy(&uip->ui_racct);
- LIST_REMOVE(uip, ui_hash);
+ if (refcount_release(&uip->ui_ref) == 0) {
rw_wunlock(&uihashtbl_lock);
- if (uip->ui_sbsize != 0)
- printf("freeing uidinfo: uid = %d, sbsize = %ld\n",
- uip->ui_uid, uip->ui_sbsize);
- if (uip->ui_proccnt != 0)
- printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
- uip->ui_uid, uip->ui_proccnt);
- if (uip->ui_vmsize != 0)
- printf("freeing uidinfo: uid = %d, swapuse = %lld\n",
- uip->ui_uid, (unsigned long long)uip->ui_vmsize);
- mtx_destroy(&uip->ui_vmsize_mtx);
- free(uip, M_UIDINFO);
return;
}
- /*
- * Someone added a reference between atomic_cmpset_int() and
- * rw_wlock(&uihashtbl_lock).
- */
+
+ racct_destroy(&uip->ui_racct);
+ LIST_REMOVE(uip, ui_hash);
rw_wunlock(&uihashtbl_lock);
+
+ if (uip->ui_sbsize != 0)
+ printf("freeing uidinfo: uid = %d, sbsize = %ld\n",
+ uip->ui_uid, uip->ui_sbsize);
+ if (uip->ui_proccnt != 0)
+ printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
+ uip->ui_uid, uip->ui_proccnt);
+ if (uip->ui_vmsize != 0)
+ printf("freeing uidinfo: uid = %d, swapuse = %lld\n",
+ uip->ui_uid, (unsigned long long)uip->ui_vmsize);
+ mtx_destroy(&uip->ui_vmsize_mtx);
+ free(uip, M_UIDINFO);
}
void
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