HID: fix a lockup regression when using force feedback on a PID device

Commit 8006479c9b75fb6594a7b746af3d7f1fbb68f18f introduced a spinlock in
input_dev->event_lock, which is locked when handling input events.
However, the hid-pidff driver sleeps when handling events as it waits for
reports being sent to the device before changing the report contents
again.
This causes a system lockup when trying to use force feedback with a PID
device, a regression introduced in 2.6.24 and 2.6.23.15.

Fix it by extracting the raw report data from struct hid_report
immediately when hid_submit_report() is called, therefore allowing
drivers to change the contents of struct hid_report immediately without
affecting the already-queued transfer.

In hid-pidff, re-add the removed usbhid_wait_io() to
pidff_erase_effect() instead, to prevent a full report queue from causing
the submission to fail, thus not freeing up device memory.
pidff_erase_effect() is not called while dev->event_lock is held.

Signed-off-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index 011326178c06..484e3eec2f88 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -397,7 +397,6 @@ static void pidff_set_condition_report(struct pidff_device *pidff,
                           effect->u.condition[i].left_saturation);
                 pidff_set(&pidff->set_condition[PID_DEAD_BAND],
                           effect->u.condition[i].deadband);
-                usbhid_wait_io(pidff->hid);
                 usbhid_submit_report(pidff->hid, pidff->reports[PID_SET_CONDITION],
                                   USB_DIR_OUT);
         }
@@ -512,7 +511,6 @@ static void pidff_playback_pid(struct pidff_device *pidff, int pid_id, int n)
                 pidff->effect_operation[PID_LOOP_COUNT].value[0] = n;
         }
 
-        usbhid_wait_io(pidff->hid);
         usbhid_submit_report(pidff->hid, pidff->reports[PID_EFFECT_OPERATION],
                           USB_DIR_OUT);
 }
@@ -548,6 +546,9 @@ static int pidff_erase_effect(struct input_dev *dev, int effect_id)
         int pid_id = pidff->pid_id[effect_id];
 
         debug("starting to erase %d/%d", effect_id, pidff->pid_id[effect_id]);
+        /* Wait for the queue to clear. We do not want a full fifo to
+           prevent the effect removal. */
+        usbhid_wait_io(pidff->hid);
         pidff_playback_pid(pidff, pid_id, 0);
         pidff_erase_pid(pidff, pid_id);