[PATCH] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[PATCH] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Chuansheng Liu]

There is a race condition 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 succcessful requesting.
So we need judge if the FW_STATUS_DONE is set before calling abort
in timeout function firmware_class_timeout().

Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
---
 drivers/base/firmware_class.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8945f4e..35fffd8 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -671,6 +671,13 @@ static void firmware_class_timeout(u_long data)
 {
 	struct firmware_priv *fw_priv = (struct firmware_priv *) data;
 
+	mutex_lock(&fw_lock);
+	if (test_bit(FW_STATUS_DONE, &(fw_priv->buf->status))) {
+		mutex_unlock(&fw_lock);
+		return;
+	}
+	mutex_unlock(&fw_lock);
+
 	fw_load_abort(fw_priv);
 }
 
-- 
1.7.0.4

Re: [PATCH] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Ming Lei]

On Thu, Nov 8, 2012 at 12:45 AM, Chuansheng Liu
<chuansheng.liu@intel.com> wrote:
>
> There is a race condition 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)

Good catch, but your fix isn't correct.

>
> 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 succcessful requesting.
> So we need judge if the FW_STATUS_DONE is set before calling abort
> in timeout function firmware_class_timeout().
>
> Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
> ---
>  drivers/base/firmware_class.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 8945f4e..35fffd8 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -671,6 +671,13 @@ static void firmware_class_timeout(u_long data)
>  {
>         struct firmware_priv *fw_priv = (struct firmware_priv *) data;
>
> +       mutex_lock(&fw_lock);

mutex can't be used in interrupt context, so one candidate fix is
to convert the timeout timer into delayed work, and hold the
'fw_lock' during the work function.

> +       if (test_bit(FW_STATUS_DONE, &(fw_priv->buf->status))) {
> +               mutex_unlock(&fw_lock);
> +               return;
> +       }
> +       mutex_unlock(&fw_lock);
> +
>         fw_load_abort(fw_priv);
>  }

Also the lock of 'fw_lock' should be held when setting 'FW_STATUS_DONE'
in _request_firmware_load().

Could you send out a new patch to fix the race?

Thanks,
--
Ming Lei

RE: [PATCH] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Liu, Chuansheng]

> -----Original Message-----
> From: Ming Lei [mailto:ming.lei@canonical.com]
> Sent: Wednesday, November 07, 2012 6:40 PM
> To: Liu, Chuansheng
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] firmware loader: Fix the race FW_STATUS_DONE is
> followed by class_timeout
> 
> On Thu, Nov 8, 2012 at 12:45 AM, Chuansheng Liu
> <chuansheng.liu@intel.com> wrote:
> >
> > There is a race condition 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)
> 
> Good catch, but your fix isn't correct.
> 
> >
> > 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 succcessful requesting.
> > So we need judge if the FW_STATUS_DONE is set before calling abort
> > in timeout function firmware_class_timeout().
> >
> > Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
> > ---
> >  drivers/base/firmware_class.c |    7 +++++++
> >  1 files changed, 7 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index 8945f4e..35fffd8 100644
> > --- a/drivers/base/firmware_class.c
> > +++ b/drivers/base/firmware_class.c
> > @@ -671,6 +671,13 @@ static void firmware_class_timeout(u_long data)
> >  {
> >         struct firmware_priv *fw_priv = (struct firmware_priv *) data;
> >
> > +       mutex_lock(&fw_lock);
> 
> mutex can't be used in interrupt context, so one candidate fix is
> to convert the timeout timer into delayed work, and hold the
> 'fw_lock' during the work function.
> 
> > +       if (test_bit(FW_STATUS_DONE, &(fw_priv->buf->status))) {
> > +               mutex_unlock(&fw_lock);
> > +               return;
> > +       }
> > +       mutex_unlock(&fw_lock);
> > +
> >         fw_load_abort(fw_priv);
> >  }
> 
> Also the lock of 'fw_lock' should be held when setting 'FW_STATUS_DONE'
> in _request_firmware_load().
> 
> Could you send out a new patch to fix the race?
Thanks your review and proposal, has sent the patch V2 to be reviewed.
> 
> Thanks,
> --
> Ming Lei

[PATCH V2] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Chuansheng Liu]

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>
---
 drivers/base/firmware_class.c |   25 +++++++++++++++++--------
 1 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8945f4e..f2caa0a 100644
--- 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;
@@ -667,10 +667,17 @@ 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;
+	}
+	mutex_unlock(&fw_lock);
 	fw_load_abort(fw_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 +903,15 @@ 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 * HZ);
 
 		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);
-- 
1.7.0.4

Re: [PATCH V2] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Ming Lei]

On Thu, Nov 8, 2012 at 6:29 PM, Chuansheng Liu <chuansheng.liu@intel.com> wrote:
>
> 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>
> ---
>  drivers/base/firmware_class.c |   25 +++++++++++++++++--------
>  1 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 8945f4e..f2caa0a 100644
> --- 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;
> @@ -667,10 +667,17 @@ 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;
> +       }
> +       mutex_unlock(&fw_lock);
>         fw_load_abort(fw_priv);

fw_lock should be held when fw_load_abort(fw_priv) is running.

>  }
>
> @@ -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 +903,15 @@ 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 * HZ);

timeout is in unit of jiffies already, so multiplying by 'HZ' isn't needed.

>
>                 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);
> --
> 1.7.0.4
>
>
>

Thanks,
--
Ming Lei

RE: [PATCH V2] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Liu, Chuansheng]

> -----Original Message-----
> From: Ming Lei [mailto:ming.lei@canonical.com]
> Sent: Thursday, November 08, 2012 10:02 AM
> To: Liu, Chuansheng
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH V2] firmware loader: Fix the race FW_STATUS_DONE is
> followed by class_timeout
> 
> On Thu, Nov 8, 2012 at 6:29 PM, Chuansheng Liu <chuansheng.liu@intel.com>
> wrote:
> >
> > 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>
> > ---
> >  drivers/base/firmware_class.c |   25 +++++++++++++++++--------
> >  1 files changed, 17 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index 8945f4e..f2caa0a 100644
> > --- 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;
> > @@ -667,10 +667,17 @@ 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;
> > +       }
> > +       mutex_unlock(&fw_lock);
> >         fw_load_abort(fw_priv);
> 
> fw_lock should be held when fw_load_abort(fw_priv) is running.
OK.

> 
> >  }
> >
> > @@ -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 +903,15 @@ 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 * HZ);
> 
> timeout is in unit of jiffies already, so multiplying by 'HZ' isn't needed.
Oh, sorry for that, I just tested it in one old version.
Will update the patch soon.

> 
> >
> >                 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);
> > --
> > 1.7.0.4
> >
> >
> >
> 
> Thanks,
> --
> Ming Lei

[PATCH V3] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Chuansheng Liu]

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

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8945f4e..b44ed35 100644
--- 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);
-- 
1.7.0.4

Re: [PATCH V3] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout

[Ming Lei]

On Thu, Nov 8, 2012 at 7:14 PM, Chuansheng Liu <chuansheng.liu@intel.com> wrote:
>
> 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>

Thanks,
--
Ming Lei