[PATCH v2 1/3] binder: fix sparse warnings on locking context

Todd Kjos
2018-12-05T23:19:43Z

Add __acquire()/__release() annnotations to fix warnings
in sparse context checking

There is one case where the warning was due to a lack of
a "default:" case in a switch statement where a lock was
being released in each of the cases, so the default
case was added.

Signed-off-by: Todd Kjos <tkjos@google.com>
---
v2: no change, just resubmitted as #1 of 3 patches instead of by itself

drivers/android/binder.c | 43 +++++++++++++++++++++++++++++++++-
drivers/android/binder_alloc.c | 1 +
2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index d6979cf7b2dad..172c207fbf99d 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -660,6 +660,7 @@ struct binder_transaction {
#define binder_proc_lock(proc) _binder_proc_lock(proc, __LINE__)
static void
_binder_proc_lock(struct binder_proc *proc, int line)
+ __acquires(&proc->outer_lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
@@ -675,6 +676,7 @@ _binder_proc_lock(struct binder_proc *proc, int line)
#define binder_proc_unlock(_proc) _binder_proc_unlock(_proc, __LINE__)
static void
_binder_proc_unlock(struct binder_proc *proc, int line)
+ __releases(&proc->outer_lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
@@ -690,6 +692,7 @@ _binder_proc_unlock(struct binder_proc *proc, int line)
#define binder_inner_proc_lock(proc) _binder_inner_proc_lock(proc, __LINE__)
static void
_binder_inner_proc_lock(struct binder_proc *proc, int line)
+ __acquires(&proc->inner_lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
@@ -705,6 +708,7 @@ _binder_inner_proc_lock(struct binder_proc *proc, int line)
#define binder_inner_proc_unlock(proc) _binder_inner_proc_unlock(proc, __LINE__)
static void
_binder_inner_proc_unlock(struct binder_proc *proc, int line)
+ __releases(&proc->inner_lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
@@ -720,6 +724,7 @@ _binder_inner_proc_unlock(struct binder_proc *proc, int line)
#define binder_node_lock(node) _binder_node_lock(node, __LINE__)
static void
_binder_node_lock(struct binder_node *node, int line)
+ __acquires(&node->lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
@@ -735,6 +740,7 @@ _binder_node_lock(struct binder_node *node, int line)
#define binder_node_unlock(node) _binder_node_unlock(node, __LINE__)
static void
_binder_node_unlock(struct binder_node *node, int line)
+ __releases(&node->lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
@@ -751,12 +757,16 @@ _binder_node_unlock(struct binder_node *node, int line)
#define binder_node_inner_lock(node) _binder_node_inner_lock(node, __LINE__)
static void
_binder_node_inner_lock(struct binder_node *node, int line)
+ __acquires(&node->lock) __acquires(&node->proc->inner_lock)
{
binder_debug(BINDER_DEBUG_SPINLOCKS,
"%s: line=%d\n", __func__, line);
spin_lock(&node->lock);
if (node->proc)
binder_inner_proc_lock(node->proc);
+ else
+ /* annotation for sparse */
+ __acquire(&node->proc->inner_lock);
}

/**
@@ -768,6 +778,7 @@ _binder_node_inner_lock(struct binder_node *node, int line)
#define binder_node_inner_unlock(node) _binder_node_inner_unlock(node, __LINE__)
static void
_binder_node_inner_unlock(struct binder_node *node, int line)
+ __releases(&node->lock) __releases(&node->proc->inner_lock)
{
struct binder_proc *proc = node->proc;

@@ -775,6 +786,9 @@ _binder_node_inner_unlock(struct binder_node *node, int line)
"%s: line=%d\n", __func__, line);
if (proc)
binder_inner_proc_unlock(proc);
+ else
+ /* annotation for sparse */
+ __release(&node->proc->inner_lock);
spin_unlock(&node->lock);
}

@@ -1384,10 +1398,14 @@ static void binder_dec_node_tmpref(struct binder_node *node)
binder_node_inner_lock(node);
if (!node->proc)
spin_lock(&binder_dead_nodes_lock);
+ else
+ __acquire(&binder_dead_nodes_lock);
node->tmp_refs--;
BUG_ON(node->tmp_refs < 0);
if (!node->proc)
spin_unlock(&binder_dead_nodes_lock);
+ else
+ __release(&binder_dead_nodes_lock);
/*
* Call binder_dec_node() to check if all refcounts are 0
* and cleanup is needed. Calling with strong=0 and internal=1
@@ -1890,18 +1908,22 @@ static struct binder_thread *binder_get_txn_from(
*/
static struct binder_thread *binder_get_txn_from_and_acq_inner(
struct binder_transaction *t)
+ __acquires(&t->from->proc->inner_lock)
{
struct binder_thread *from;

from = binder_get_txn_from(t);
- if (!from)
+ if (!from) {
+ __acquire(&from->proc->inner_lock);
return NULL;
+ }
binder_inner_proc_lock(from->proc);
if (t->from) {
BUG_ON(from != t->from);
return from;
}
binder_inner_proc_unlock(from->proc);
+ __acquire(&from->proc->inner_lock);
binder_thread_dec_tmpref(from);
return NULL;
}
@@ -1973,6 +1995,8 @@ static void binder_send_failed_reply(struct binder_transaction *t,
binder_thread_dec_tmpref(target_thread);
binder_free_transaction(t);
return;
+ } else {
+ __release(&target_thread->proc->inner_lock);
}
next = t->from_parent;

@@ -2394,11 +2418,15 @@ static int binder_translate_handle(struct flat_binder_object *fp,
fp->cookie = node->cookie;
if (node->proc)
binder_inner_proc_lock(node->proc);
+ else
+ __acquire(&node->proc->inner_lock);
binder_inc_node_nilocked(node,
fp->hdr.type == BINDER_TYPE_BINDER,
0, NULL);
if (node->proc)
binder_inner_proc_unlock(node->proc);
+ else
+ __release(&node->proc->inner_lock);
trace_binder_transaction_ref_to_node(t, node, &src_rdata);
binder_debug(BINDER_DEBUG_TRANSACTION,
" ref %d desc %d -> node %d u%016llx\n",
@@ -2762,6 +2790,8 @@ static void binder_transaction(struct binder_proc *proc,
binder_set_nice(in_reply_to->saved_priority);
target_thread = binder_get_txn_from_and_acq_inner(in_reply_to);
if (target_thread == NULL) {
+ /* annotation for sparse */
+ __release(&target_thread->proc->inner_lock);
return_error = BR_DEAD_REPLY;
return_error_line = __LINE__;
goto err_dead_binder;
@@ -4164,6 +4194,11 @@ static int binder_thread_read(struct binder_proc *proc,
if (cmd == BR_DEAD_BINDER)
goto done; /* DEAD_BINDER notifications can cause transactions */
} break;
+ default:
+ binder_inner_proc_unlock(proc);
+ pr_err("%d:%d: bad work type %d\n",
+ proc->pid, thread->pid, w->type);
+ break;
}

if (!t)
@@ -4467,6 +4502,8 @@ static int binder_thread_release(struct binder_proc *proc,
spin_lock(&t->lock);
if (t->to_thread == thread)
send_reply = t;
+ } else {
+ __acquire(&t->lock);
}
thread->is_dead = true;

@@ -4495,7 +4532,11 @@ static int binder_thread_release(struct binder_proc *proc,
spin_unlock(&last_t->lock);
if (t)
spin_lock(&t->lock);
+ else
+ __acquire(&t->lock);
}
+ /* annotation for sparse, lock not acquired in last iteration above */
+ __release(&t->lock);

/*
* If this thread used poll, make sure we remove the waitqueue
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 030c98f35cca7..022cd80e80cc3 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -939,6 +939,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
struct list_lru_one *lru,
spinlock_t *lock,
void *cb_arg)
+ __must_hold(lock)
{
struct mm_struct *mm = NULL;
struct binder_lru_page *page = container_of(item,
--
2.20.0.rc1.387.gf8505762e3-goog