SELinux: code readability with avc_cache
The code making use of struct avc_cache was not easy to read thanks to liberal
use of &avc_cache.{slots_lock,slots}[hvalue] throughout. This patch simply
creates local pointers and uses those instead of the long global names.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 326aa78..9dd5c50 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -92,12 +92,12 @@
struct avc_node {
struct avc_entry ae;
- struct list_head list;
+ struct list_head list; /* anchored in avc_cache->slots[i] */
struct rcu_head rhead;
};
struct avc_cache {
- struct list_head slots[AVC_CACHE_SLOTS];
+ struct list_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
atomic_t lru_hint; /* LRU hint for reclaim scan */
atomic_t active_nodes;
@@ -249,16 +249,18 @@
{
int i, chain_len, max_chain_len, slots_used;
struct avc_node *node;
+ struct list_head *head;
rcu_read_lock();
slots_used = 0;
max_chain_len = 0;
for (i = 0; i < AVC_CACHE_SLOTS; i++) {
- if (!list_empty(&avc_cache.slots[i])) {
+ head = &avc_cache.slots[i];
+ if (!list_empty(head)) {
slots_used++;
chain_len = 0;
- list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
+ list_for_each_entry_rcu(node, head, list)
chain_len++;
if (chain_len > max_chain_len)
max_chain_len = chain_len;
@@ -306,26 +308,30 @@
struct avc_node *node;
int hvalue, try, ecx;
unsigned long flags;
+ struct list_head *head;
+ spinlock_t *lock;
for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
+ head = &avc_cache.slots[hvalue];
+ lock = &avc_cache.slots_lock[hvalue];
- if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
+ if (!spin_trylock_irqsave(lock, flags))
continue;
rcu_read_lock();
- list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
+ list_for_each_entry(node, head, list) {
avc_node_delete(node);
avc_cache_stats_incr(reclaims);
ecx++;
if (ecx >= AVC_CACHE_RECLAIM) {
rcu_read_unlock();
- spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
+ spin_unlock_irqrestore(lock, flags);
goto out;
}
}
rcu_read_unlock();
- spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
+ spin_unlock_irqrestore(lock, flags);
}
out:
return ecx;
@@ -362,9 +368,11 @@
{
struct avc_node *node, *ret = NULL;
int hvalue;
+ struct list_head *head;
hvalue = avc_hash(ssid, tsid, tclass);
- list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
+ head = &avc_cache.slots[hvalue];
+ list_for_each_entry_rcu(node, head, list) {
if (ssid == node->ae.ssid &&
tclass == node->ae.tclass &&
tsid == node->ae.tsid) {
@@ -453,11 +461,17 @@
node = avc_alloc_node();
if (node) {
+ struct list_head *head;
+ spinlock_t *lock;
+
hvalue = avc_hash(ssid, tsid, tclass);
avc_node_populate(node, ssid, tsid, tclass, avd);
- spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
- list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
+ head = &avc_cache.slots[hvalue];
+ lock = &avc_cache.slots_lock[hvalue];
+
+ spin_lock_irqsave(lock, flag);
+ list_for_each_entry(pos, head, list) {
if (pos->ae.ssid == ssid &&
pos->ae.tsid == tsid &&
pos->ae.tclass == tclass) {
@@ -465,9 +479,9 @@
goto found;
}
}
- list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
+ list_add_rcu(&node->list, head);
found:
- spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
+ spin_unlock_irqrestore(lock, flag);
}
out:
return node;
@@ -736,6 +750,8 @@
int hvalue, rc = 0;
unsigned long flag;
struct avc_node *pos, *node, *orig = NULL;
+ struct list_head *head;
+ spinlock_t *lock;
node = avc_alloc_node();
if (!node) {
@@ -745,9 +761,13 @@
/* Lock the target slot */
hvalue = avc_hash(ssid, tsid, tclass);
- spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
- list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
+ head = &avc_cache.slots[hvalue];
+ lock = &avc_cache.slots_lock[hvalue];
+
+ spin_lock_irqsave(lock, flag);
+
+ list_for_each_entry(pos, head, list) {
if (ssid == pos->ae.ssid &&
tsid == pos->ae.tsid &&
tclass == pos->ae.tclass &&
@@ -792,7 +812,7 @@
}
avc_node_replace(node, orig);
out_unlock:
- spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
+ spin_unlock_irqrestore(lock, flag);
out:
return rc;
}
@@ -807,18 +827,23 @@
int i, rc = 0, tmprc;
unsigned long flag;
struct avc_node *node;
+ struct list_head *head;
+ spinlock_t *lock;
for (i = 0; i < AVC_CACHE_SLOTS; i++) {
- spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
+ head = &avc_cache.slots[i];
+ lock = &avc_cache.slots_lock[i];
+
+ spin_lock_irqsave(lock, flag);
/*
* With preemptable RCU, the outer spinlock does not
* prevent RCU grace periods from ending.
*/
rcu_read_lock();
- list_for_each_entry(node, &avc_cache.slots[i], list)
+ list_for_each_entry(node, head, list)
avc_node_delete(node);
rcu_read_unlock();
- spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
+ spin_unlock_irqrestore(lock, flag);
}
for (c = avc_callbacks; c; c = c->next) {
