firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

There is a race as below when calling request_firmware():
CPU1                                   CPU2
write 0 > loading
mutex_lock(&fw_lock)
...
set_bit FW_STATUS_DONE                 class_timeout is coming
                                       set_bit FW_STATUS_ABORT
complete_all &completion
...
mutex_unlock(&fw_lock)

In this time, the bit FW_STATUS_DONE and FW_STATUS_ABORT are set,
and request_firmware() will return failure due to condition in
_request_firmware_load():
	if (!buf->size || test_bit(FW_STATUS_ABORT, &buf->status))
		retval = -ENOENT;

But from the above scenerio, it should be a successful requesting.
So we need judge if the bit FW_STATUS_DONE is already set before
calling fw_load_abort() in timeout function.

As Ming's proposal, we need change the timer into sched_work to
benefit from using &fw_lock mutex also.

Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Acked-by: Ming Lei <ming.lei@canonical.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8945f4e..b44ed35 100644 (file)
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -143,7 +143,7 @@ struct fw_cache_entry {
 };
 
 struct firmware_priv {
-       struct timer_list timeout;
+       struct delayed_work timeout_work;
        bool nowait;
        struct device dev;
        struct firmware_buf *buf;
@@ -667,11 +667,18 @@ static struct bin_attribute firmware_attr_data = {
        .write = firmware_data_write,
 };
 
-static void firmware_class_timeout(u_long data)
+static void firmware_class_timeout_work(struct work_struct *work)
 {
-       struct firmware_priv *fw_priv = (struct firmware_priv *) data;
+       struct firmware_priv *fw_priv = container_of(work,
+                       struct firmware_priv, timeout_work.work);
 
+       mutex_lock(&fw_lock);
+       if (test_bit(FW_STATUS_DONE, &(fw_priv->buf->status))) {
+               mutex_unlock(&fw_lock);
+               return;
+       }
        fw_load_abort(fw_priv);
+       mutex_unlock(&fw_lock);
 }
 
 static struct firmware_priv *
@@ -690,8 +697,8 @@ fw_create_instance(struct firmware *firmware, const char *fw_name,
 
        fw_priv->nowait = nowait;
        fw_priv->fw = firmware;
-       setup_timer(&fw_priv->timeout,
-                   firmware_class_timeout, (u_long) fw_priv);
+       INIT_DELAYED_WORK(&fw_priv->timeout_work,
+               firmware_class_timeout_work);
 
        f_dev = &fw_priv->dev;
 
@@ -858,7 +865,9 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
                dev_dbg(f_dev->parent, "firmware: direct-loading"
                        " firmware %s\n", buf->fw_id);
 
+               mutex_lock(&fw_lock);
                set_bit(FW_STATUS_DONE, &buf->status);
+               mutex_unlock(&fw_lock);
                complete_all(&buf->completion);
                direct_load = 1;
                goto handle_fw;
@@ -894,15 +903,14 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
                dev_set_uevent_suppress(f_dev, false);
                dev_dbg(f_dev, "firmware: requesting %s\n", buf->fw_id);
                if (timeout != MAX_SCHEDULE_TIMEOUT)
-                       mod_timer(&fw_priv->timeout,
-                                 round_jiffies_up(jiffies + timeout));
+                       schedule_delayed_work(&fw_priv->timeout_work, timeout);
 
                kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
        }
 
        wait_for_completion(&buf->completion);
 
-       del_timer_sync(&fw_priv->timeout);
+       cancel_delayed_work_sync(&fw_priv->timeout_work);
 
 handle_fw:
        mutex_lock(&fw_lock);