[PATCH v4 2/2] selinux: complete the inlining of hashtab functions

[Ondrej Mosnacek <omosnace@redhat.com>]

Move (most of) the definitions of hashtab_search() and hashtab_insert()
to the header file. In combination with the previous patch, this avoids
calling the callbacks indirectly by function pointers and allows for
better optimization, leading to a drastic performance improvement of
these operations.

With this patch, I measured a speed up in the following areas (measured
on x86_64 F32 VM with 4 CPUs):
  1. Policy load (`load_policy`) - takes ~150 ms instead of ~230 ms.
  2. `chcon -R unconfined_u:object_r:user_tmp_t:s0:c381,c519 /tmp/linux-src`
     where /tmp/linux-src is an extracted linux-5.7 source tarball -
     takes ~522 ms instead of ~576 ms. This is because of many
     symtab_search() calls in string_to_context_struct() when there are
     many categories specified in the context.
  3. `stress-ng --msg 1 --msg-ops 10000000` - takes 12.41 s instead of
     13.95 s (consumes 18.6 s of kernel CPU time instead of 21.6 s).
     This is thanks to security_transition_sid() being ~43% faster after
     this patch.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
---
 security/selinux/ss/hashtab.c | 59 +++-----------------------------
 security/selinux/ss/hashtab.h | 63 ++++++++++++++++++++++++++++++++---
 2 files changed, 63 insertions(+), 59 deletions(-)

diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
index 8126b909a7574..d9287bb4bfebb 100644
--- a/security/selinux/ss/hashtab.c
+++ b/security/selinux/ss/hashtab.c
@@ -7,7 +7,6 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
-#include <linux/sched.h>
 #include "hashtab.h"
 
 static struct kmem_cache *hashtab_node_cachep;
@@ -40,71 +39,23 @@ int hashtab_init(struct hashtab *h, u32 nel_hint)
 	return h->htable ? 0 : -ENOMEM;
 }
 
-int hashtab_insert(struct hashtab *h, void *key, void *datum,
-		   struct hashtab_key_params key_params)
+int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
+		     void *key, void *datum)
 {
-	u32 hvalue;
-	struct hashtab_node *prev, *cur, *newnode;
-
-	cond_resched();
-
-	if (!h->size || h->nel == HASHTAB_MAX_NODES)
-		return -EINVAL;
-
-	hvalue = key_params.hash(key) & (h->size - 1);
-	prev = NULL;
-	cur = h->htable[hvalue];
-	while (cur) {
-		int cmp = key_params.cmp(key, cur->key);
-
-		if (cmp == 0)
-			return -EEXIST;
-		if (cmp < 0)
-			break;
-		prev = cur;
-		cur = cur->next;
-	}
+	struct hashtab_node *newnode;
 
 	newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
 	if (!newnode)
 		return -ENOMEM;
 	newnode->key = key;
 	newnode->datum = datum;
-	if (prev) {
-		newnode->next = prev->next;
-		prev->next = newnode;
-	} else {
-		newnode->next = h->htable[hvalue];
-		h->htable[hvalue] = newnode;
-	}
+	newnode->next = *dst;
+	*dst = newnode;
 
 	h->nel++;
 	return 0;
 }
 
-void *hashtab_search(struct hashtab *h, const void *key,
-		     struct hashtab_key_params key_params)
-{
-	u32 hvalue;
-	struct hashtab_node *cur;
-
-	if (!h->size)
-		return NULL;
-
-	hvalue = key_params.hash(key) & (h->size - 1);
-	cur = h->htable[hvalue];
-	while (cur) {
-		int cmp = key_params.cmp(key, cur->key);
-
-		if (cmp == 0)
-			return cur->datum;
-		if (cmp < 0)
-			break;
-		cur = cur->next;
-	}
-	return NULL;
-}
-
 void hashtab_destroy(struct hashtab *h)
 {
 	u32 i;
diff --git a/security/selinux/ss/hashtab.h b/security/selinux/ss/hashtab.h
index 4885234257d40..3c952f0f01f9c 100644
--- a/security/selinux/ss/hashtab.h
+++ b/security/selinux/ss/hashtab.h
@@ -11,7 +11,11 @@
 #ifndef _SS_HASHTAB_H_
 #define _SS_HASHTAB_H_
 
-#define HASHTAB_MAX_NODES	0xffffffff
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+
+#define HASHTAB_MAX_NODES	U32_MAX
 
 struct hashtab_key_params {
 	u32 (*hash)(const void *key);	/* hash function */
@@ -43,6 +47,9 @@ struct hashtab_info {
  */
 int hashtab_init(struct hashtab *h, u32 nel_hint);
 
+int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
+		     void *key, void *datum);
+
 /*
  * Inserts the specified (key, datum) pair into the specified hash table.
  *
@@ -51,8 +58,34 @@ int hashtab_init(struct hashtab *h, u32 nel_hint);
  * -EINVAL for general errors or
   0 otherwise.
  */
-int hashtab_insert(struct hashtab *h, void *k, void *d,
-		   struct hashtab_key_params key_params);
+static inline int hashtab_insert(struct hashtab *h, void *key, void *datum,
+				 struct hashtab_key_params key_params)
+{
+	u32 hvalue;
+	struct hashtab_node *prev, *cur;
+
+	cond_resched();
+
+	if (!h->size || h->nel == HASHTAB_MAX_NODES)
+		return -EINVAL;
+
+	hvalue = key_params.hash(key) & (h->size - 1);
+	prev = NULL;
+	cur = h->htable[hvalue];
+	while (cur) {
+		int cmp = key_params.cmp(key, cur->key);
+
+		if (cmp == 0)
+			return -EEXIST;
+		if (cmp < 0)
+			break;
+		prev = cur;
+		cur = cur->next;
+	}
+
+	return __hashtab_insert(h, prev ? &prev->next : &h->htable[hvalue],
+				key, datum);
+}
 
 /*
  * Searches for the entry with the specified key in the hash table.
@@ -60,8 +93,28 @@ int hashtab_insert(struct hashtab *h, void *k, void *d,
  * Returns NULL if no entry has the specified key or
  * the datum of the entry otherwise.
  */
-void *hashtab_search(struct hashtab *h, const void *k,
-		     struct hashtab_key_params key_params);
+static inline void *hashtab_search(struct hashtab *h, const void *key,
+				   struct hashtab_key_params key_params)
+{
+	u32 hvalue;
+	struct hashtab_node *cur;
+
+	if (!h->size)
+		return NULL;
+
+	hvalue = key_params.hash(key) & (h->size - 1);
+	cur = h->htable[hvalue];
+	while (cur) {
+		int cmp = key_params.cmp(key, cur->key);
+
+		if (cmp == 0)
+			return cur->datum;
+		if (cmp < 0)
+			break;
+		cur = cur->next;
+	}
+	return NULL;
+}
 
 /*
  * Destroys the specified hash table.
-- 
2.26.2