misc: mic: Fix crash when MIC reset is invoked in RESET_FAILED state

This patch fixes the following crash seen when MIC reset is invoked in
RESET_FAILED state due to device_del being called a second time on an
already deleted device:

[<ffffffff813b2295>] device_del+0x45/0x1d0
[<ffffffff813b243e>] device_unregister+0x1e/0x60
[<ffffffffa040f1c2>] scif_unregister_device+0x12/0x20 [scif_bus]
[<ffffffffa042f75a>] cosm_stop+0xaa/0xe0 [mic_cosm]
[<ffffffffa042f844>] cosm_reset_trigger_work+0x14/0x20 [mic_cosm]

The fix consists in realizing that because cosm_reset changes the
state to MIC_RESETTING, cosm_stop needs the previous state, before it
changed to MIC_RESETTING, to decide whether a hw_ops->stop had
previously been issued. This is now provided in a new cosm_device
member cdev->prev_state.

Reviewed-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/misc/mic/bus/cosm_bus.h b/drivers/misc/mic/bus/cosm_bus.h
index f7c57f266916..8b6341855dc3 100644
--- a/drivers/misc/mic/bus/cosm_bus.h
+++ b/drivers/misc/mic/bus/cosm_bus.h
@@ -30,6 +30,7 @@
  * @attr_group: Pointer to list of sysfs attribute groups.
  * @sdev: Device for sysfs entries.
  * @state: MIC state.
+ * @prev_state: MIC state previous to MIC_RESETTING
  * @shutdown_status: MIC status reported by card for shutdown/crashes.
  * @shutdown_status_int: Internal shutdown status maintained by the driver
  * @cosm_mutex: Mutex for synchronizing access to data structures.
@@ -55,6 +56,7 @@ struct cosm_device {
         const struct attribute_group **attr_group;
         struct device *sdev;
         u8 state;
+        u8 prev_state;
         u8 shutdown_status;
         u8 shutdown_status_int;
         struct mutex cosm_mutex;