ion:synchronize debugfs callback and ion_client_destroy
There are race condition B/T ion_client_destroy and debugfs callbacks.
Let's use a mutex to synchronize them.
Signed-off-by: Neil Zhang <neilzhang1123@hotmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index d669848..7ff2a7e 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -677,6 +677,34 @@
}
EXPORT_SYMBOL(ion_unmap_kernel);
+static struct mutex debugfs_mutex;
+static struct rb_root *ion_root_client;
+static int is_client_alive(struct ion_client *client)
+{
+ struct rb_node *node;
+ struct ion_client *tmp;
+ struct ion_device *dev;
+
+ node = ion_root_client->rb_node;
+ dev = container_of(ion_root_client, struct ion_device, clients);
+
+ down_read(&dev->lock);
+ while (node) {
+ tmp = rb_entry(node, struct ion_client, node);
+ if (client < tmp) {
+ node = node->rb_left;
+ } else if (client > tmp) {
+ node = node->rb_right;
+ } else {
+ up_read(&dev->lock);
+ return 1;
+ }
+ }
+
+ up_read(&dev->lock);
+ return 0;
+}
+
static int ion_debug_client_show(struct seq_file *s, void *unused)
{
struct ion_client *client = s->private;
@@ -685,6 +713,14 @@
const char *names[ION_NUM_HEAP_IDS] = {NULL};
int i;
+ mutex_lock(&debugfs_mutex);
+ if (!is_client_alive(client)) {
+ seq_printf(s, "ion_client 0x%p dead, can't dump its buffers\n",
+ client);
+ mutex_unlock(&debugfs_mutex);
+ return 0;
+ }
+
mutex_lock(&client->lock);
for (n = rb_first(&client->handles); n; n = rb_next(n)) {
struct ion_handle *handle = rb_entry(n, struct ion_handle,
@@ -696,6 +732,7 @@
sizes[id] += handle->buffer->size;
}
mutex_unlock(&client->lock);
+ mutex_unlock(&debugfs_mutex);
seq_printf(s, "%16.16s: %16.16s\n", "heap_name", "size_in_bytes");
for (i = 0; i < ION_NUM_HEAP_IDS; i++) {
@@ -832,6 +869,7 @@
struct rb_node *n;
pr_debug("%s: %d\n", __func__, __LINE__);
+ mutex_lock(&debugfs_mutex);
while ((n = rb_first(&client->handles))) {
struct ion_handle *handle = rb_entry(n, struct ion_handle,
node);
@@ -850,6 +888,7 @@
kfree(client->display_name);
kfree(client->name);
kfree(client);
+ mutex_unlock(&debugfs_mutex);
}
EXPORT_SYMBOL(ion_client_destroy);
@@ -1415,6 +1454,7 @@
seq_printf(s, "%16s %16s %16s\n", "client", "pid", "size");
seq_puts(s, "----------------------------------------------------\n");
+ mutex_lock(&debugfs_mutex);
for (n = rb_first(&dev->clients); n; n = rb_next(n)) {
struct ion_client *client = rb_entry(n, struct ion_client,
node);
@@ -1433,6 +1473,8 @@
client->pid, size);
}
}
+ mutex_unlock(&debugfs_mutex);
+
seq_puts(s, "----------------------------------------------------\n");
seq_puts(s, "orphaned allocations (info is from last known client):\n");
mutex_lock(&dev->buffer_lock);
@@ -1617,6 +1659,8 @@
init_rwsem(&idev->lock);
plist_head_init(&idev->heaps);
idev->clients = RB_ROOT;
+ ion_root_client = &idev->clients;
+ mutex_init(&debugfs_mutex);
return idev;
}
EXPORT_SYMBOL(ion_device_create);