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Date: Thu, 13 Nov 2014 14:24:12 -0500
From: Pranith Kumar <bobby.prani@...il.com>
To: David Howells <dhowells@...hat.com>,
James Morris <james.l.morris@...cle.com>,
"Serge E. Hallyn" <serge@...lyn.com>,
Stephen Hemminger <shemming@...cade.com>,
Andreea-Cristina Bernat <bernat.ada@...il.com>,
linux-kernel@...r.kernel.org (open list),
keyrings@...ux-nfs.org (open list:KEYS/KEYRINGS:),
linux-security-module@...r.kernel.org (open list:SECURITY SUBSYSTEM)
Cc: paulmck@...ux.vnet.ibm.com
Subject: [PATCH 06/16] assoc_array: Replace smp_read_barrier_depends() with lockless_dereference()
Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
I replaced the inline functions dereferencing pointer 'x' to use
lockless_dereference() because of which we do not need to litter the code with
smp_read_barrier_depends().
Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
include/linux/assoc_array_priv.h | 11 +++++++----
lib/assoc_array.c | 7 -------
security/keys/keyring.c | 6 ------
3 files changed, 7 insertions(+), 17 deletions(-)
diff --git a/include/linux/assoc_array_priv.h b/include/linux/assoc_array_priv.h
index 711275e..96449c3 100644
--- a/include/linux/assoc_array_priv.h
+++ b/include/linux/assoc_array_priv.h
@@ -118,7 +118,8 @@ struct assoc_array_edit {
static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x)
{
- return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK;
+ return (unsigned long)lockless_dereference(x) &
+ ASSOC_ARRAY_PTR_TYPE_MASK;
}
static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x)
{
@@ -126,7 +127,8 @@ static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x)
}
static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x)
{
- return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK;
+ return (unsigned long)lockless_dereference(x) &
+ ASSOC_ARRAY_PTR_SUBTYPE_MASK;
}
static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x)
{
@@ -135,13 +137,14 @@ static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x)
static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x)
{
- return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK);
+ return (void *)((unsigned long)lockless_dereference(x) &
+ ~ASSOC_ARRAY_PTR_TYPE_MASK);
}
static inline
unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x)
{
- return (unsigned long)x &
+ return (unsigned long)lockless_dereference(x) &
~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK);
}
static inline
diff --git a/lib/assoc_array.c b/lib/assoc_array.c
index 2404d03..5b62033 100644
--- a/lib/assoc_array.c
+++ b/lib/assoc_array.c
@@ -37,12 +37,10 @@ begin_node:
if (assoc_array_ptr_is_shortcut(cursor)) {
/* Descend through a shortcut */
shortcut = assoc_array_ptr_to_shortcut(cursor);
- smp_read_barrier_depends();
cursor = ACCESS_ONCE(shortcut->next_node);
}
node = assoc_array_ptr_to_node(cursor);
- smp_read_barrier_depends();
slot = 0;
/* We perform two passes of each node.
@@ -85,7 +83,6 @@ begin_node:
continue_node:
node = assoc_array_ptr_to_node(cursor);
- smp_read_barrier_depends();
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
ptr = ACCESS_ONCE(node->slots[slot]);
@@ -104,7 +101,6 @@ finished_node:
if (assoc_array_ptr_is_shortcut(parent)) {
shortcut = assoc_array_ptr_to_shortcut(parent);
- smp_read_barrier_depends();
cursor = parent;
parent = ACCESS_ONCE(shortcut->back_pointer);
slot = shortcut->parent_slot;
@@ -215,7 +211,6 @@ jumped:
consider_node:
node = assoc_array_ptr_to_node(cursor);
- smp_read_barrier_depends();
slot = segments >> (level & ASSOC_ARRAY_KEY_CHUNK_MASK);
slot &= ASSOC_ARRAY_FAN_MASK;
@@ -253,7 +248,6 @@ consider_node:
cursor = ptr;
follow_shortcut:
shortcut = assoc_array_ptr_to_shortcut(cursor);
- smp_read_barrier_depends();
pr_devel("shortcut to %d\n", shortcut->skip_to_level);
sc_level = level + ASSOC_ARRAY_LEVEL_STEP;
BUG_ON(sc_level > shortcut->skip_to_level);
@@ -343,7 +337,6 @@ void *assoc_array_find(const struct assoc_array *array,
* actually going to dereference it.
*/
leaf = assoc_array_ptr_to_leaf(ptr);
- smp_read_barrier_depends();
if (ops->compare_object(leaf, index_key))
return (void *)leaf;
}
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 8177010..48d3464 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -683,7 +683,6 @@ descend_to_keyring:
* doesn't contain any keyring pointers.
*/
shortcut = assoc_array_ptr_to_shortcut(ptr);
- smp_read_barrier_depends();
if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
goto not_this_keyring;
@@ -693,7 +692,6 @@ descend_to_keyring:
}
node = assoc_array_ptr_to_node(ptr);
- smp_read_barrier_depends();
ptr = node->slots[0];
if (!assoc_array_ptr_is_meta(ptr))
@@ -706,7 +704,6 @@ descend_to_node:
kdebug("descend");
if (assoc_array_ptr_is_shortcut(ptr)) {
shortcut = assoc_array_ptr_to_shortcut(ptr);
- smp_read_barrier_depends();
ptr = ACCESS_ONCE(shortcut->next_node);
BUG_ON(!assoc_array_ptr_is_node(ptr));
}
@@ -714,7 +711,6 @@ descend_to_node:
begin_node:
kdebug("begin_node");
- smp_read_barrier_depends();
slot = 0;
ascend_to_node:
/* Go through the slots in a node */
@@ -762,14 +758,12 @@ ascend_to_node:
if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
shortcut = assoc_array_ptr_to_shortcut(ptr);
- smp_read_barrier_depends();
ptr = ACCESS_ONCE(shortcut->back_pointer);
slot = shortcut->parent_slot;
}
if (!ptr)
goto not_this_keyring;
node = assoc_array_ptr_to_node(ptr);
- smp_read_barrier_depends();
slot++;
/* If we've ascended to the root (zero backpointer), we must have just
--
1.9.1
--
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