refcount_t type and corresponding API can protect refcounters from
accidental underflow and overflow and further use-after-free situations.
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
---
fs/fscache/operation.c | 38 +++++++++++++++++++-------------------
include/linux/fscache-cache.h | 3 ++-
2 files changed, 21 insertions(+), 20 deletions(-)
diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c
index 4a5651d4904e..619ed21d24e7 100644
--- a/fs/fscache/operation.c
+++ b/fs/fscache/operation.c
@@ -35,7 +35,7 @@ void fscache_operation_init(struct fscache_cookie *cookie,
fscache_operation_release_t release)
{
INIT_WORK(&op->work, fscache_op_work_func);
- atomic_set(&op->usage, 1);
+ refcount_set(&op->usage, 1);
op->state = FSCACHE_OP_ST_INITIALISED;
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
op->processor = processor;
@@ -60,12 +60,12 @@ void fscache_enqueue_operation(struct fscache_operation *op)
struct fscache_cookie *cookie = op->object->cookie;
_enter("{OBJ%x OP%x,%u}",
- op->object->debug_id, op->debug_id, atomic_read(&op->usage));
+ op->object->debug_id, op->debug_id, refcount_read(&op->usage));
ASSERT(list_empty(&op->pend_link));
ASSERT(op->processor != NULL);
ASSERT(fscache_object_is_available(op->object));
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
ASSERTIFCMP(op->state != FSCACHE_OP_ST_IN_PROGRESS,
op->state, ==, FSCACHE_OP_ST_CANCELLED);
@@ -74,7 +74,7 @@ void fscache_enqueue_operation(struct fscache_operation *op)
case FSCACHE_OP_ASYNC:
trace_fscache_op(cookie, op, fscache_op_enqueue_async);
_debug("queue async");
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
if (!queue_work(fscache_op_wq, &op->work))
fscache_put_operation(op);
break;
@@ -163,7 +163,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
trace_fscache_op(object->cookie, op, fscache_op_submit_ex);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
@@ -190,11 +190,11 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
object->n_exclusive++; /* reads and writes must wait */
if (object->n_in_progress > 0) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
@@ -210,7 +210,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
op->object = object;
object->n_ops++;
object->n_exclusive++; /* reads and writes must wait */
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
@@ -245,12 +245,12 @@ int fscache_submit_op(struct fscache_object *object,
int ret;
_enter("{OBJ%x OP%x},{%u}",
- object->debug_id, op->debug_id, atomic_read(&op->usage));
+ object->debug_id, op->debug_id, refcount_read(&op->usage));
trace_fscache_op(object->cookie, op, fscache_op_submit);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
@@ -276,11 +276,11 @@ int fscache_submit_op(struct fscache_object *object,
object->n_ops++;
if (object->n_exclusive > 0) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
@@ -292,7 +292,7 @@ int fscache_submit_op(struct fscache_object *object,
} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
op->object = object;
object->n_ops++;
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
@@ -370,7 +370,7 @@ int fscache_cancel_op(struct fscache_operation *op,
ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
spin_lock(&object->lock);
@@ -497,11 +497,11 @@ void fscache_put_operation(struct fscache_operation *op)
_enter("{OBJ%x OP%x,%d}",
op->object ? op->object->debug_id : 0,
- op->debug_id, atomic_read(&op->usage));
+ op->debug_id, refcount_read(&op->usage));
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
- if (!atomic_dec_and_test(&op->usage))
+ if (!refcount_dec_and_test(&op->usage))
return;
trace_fscache_op(op->object ? op->object->cookie : NULL, op, fscache_op_put);
@@ -589,7 +589,7 @@ void fscache_operation_gc(struct work_struct *work)
object->debug_id, op->debug_id);
fscache_stat(&fscache_n_op_gc);
- ASSERTCMP(atomic_read(&op->usage), ==, 0);
+ ASSERTCMP(refcount_read(&op->usage), ==, 0);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
ASSERTCMP(object->n_ops, >, 0);
@@ -619,7 +619,7 @@ void fscache_op_work_func(struct work_struct *work)
unsigned long start;
_enter("{OBJ%x OP%x,%d}",
- op->object->debug_id, op->debug_id, atomic_read(&op->usage));
+ op->object->debug_id, op->debug_id, refcount_read(&op->usage));
trace_fscache_op(op->object->cookie, op, fscache_op_work);
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 3235ddbdcc09..9fddf7817948 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -14,6 +14,7 @@
#ifndef _LINUX_FSCACHE_CACHE_H
#define _LINUX_FSCACHE_CACHE_H
+#include <linux/refcount.h>
#include <linux/fscache.h>
#include <linux/sched.h>
#include <linux/workqueue.h>
@@ -110,7 +111,7 @@ struct fscache_operation {
#define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */
enum fscache_operation_state state;
- atomic_t usage;
+ refcount_t usage;
unsigned debug_id; /* debugging ID */
/* operation processor callback
--
2.7.4
--
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