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greybus: timesync: Enforce TimeSync locks as subordinate to Interface locks

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gb_timesync_svc_teardown() is called from gb_timesync_svc_del() and issues a
command to a remote Interface to switch off its timers. The lock ordering
is TimeSync => Interface in this case. However gb_module_del() takes an
Interface lock then calls gb_interface_del() => gb_timesync_svc_del() in
this case the lock ordering is Interface => TimeSync.

This patch fixes by removing the taking of the Interface mutex in
gb_interface_timesync_do_something(). If an Interface is present in the
TimeSync linked-list - it is by definition intf->enabled.

Reported-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Bryan O'Donoghue 2016-06-23 16:26:00 +01:00 committed by Greg Kroah-Hartman
parent 5e2b63915c
commit 1211915127
1 changed files with 9 additions and 41 deletions
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50
drivers/staging/greybus/interface.c
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@ -872,59 +872,27 @@ void gb_interface_disable(struct gb_interface *intf)
intf->enabled = false;
}
/*
* Enable TimeSync on an Interface control connection.
*
* Locking: Takes and releases the interface mutex.
*/
/* Enable TimeSync on an Interface control connection. */
int gb_interface_timesync_enable(struct gb_interface *intf, u8 count,
u64 frame_time, u32 strobe_delay, u32 refclk)
{
int ret = -ENODEV;
mutex_lock(&intf->mutex);
if (intf->enabled) {
ret = gb_control_timesync_enable(intf->control, count,
frame_time, strobe_delay,
refclk);
}
mutex_unlock(&intf->mutex);
return ret;
return gb_control_timesync_enable(intf->control, count,
frame_time, strobe_delay,
refclk);
}
/*
* Disable TimeSync on an Interface control connection.
*
* Locking: Takes and releases the interface mutex.
*/
/* Disable TimeSync on an Interface control connection. */
int gb_interface_timesync_disable(struct gb_interface *intf)
{
int ret = -ENODEV;
mutex_lock(&intf->mutex);
if (intf->enabled)
ret = gb_control_timesync_disable(intf->control);
mutex_unlock(&intf->mutex);
return ret;
return gb_control_timesync_disable(intf->control);
}
/*
* Transmit the Authoritative FrameTime via an Interface control connection.
*
* Locking: Takes and releases the interface mutex.
*/
/* Transmit the Authoritative FrameTime via an Interface control connection. */
int gb_interface_timesync_authoritative(struct gb_interface *intf,
u64 *frame_time)
{
int ret = -ENODEV;
mutex_lock(&intf->mutex);
if (intf->enabled) {
ret = gb_control_timesync_authoritative(intf->control,
frame_time);
}
mutex_unlock(&intf->mutex);
return ret;
return gb_control_timesync_authoritative(intf->control,
frame_time);
}
/* Register an interface. */