[ 002/123] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

Greg Kroah-Hartman
2013-01-09T20:36:54Z

From: Chuansheng Liu <chuansheng.liu@intel.com>

commit ce2fcbd99cef580623116bb33531dbc3e6f690b0 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/base/firmware_class.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)

--- 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_att
.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 *firm

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
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
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);