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, 6 insertions, 0 deletions

diff --git a/include/linux/hid.h b/include/linux/hid.h
index dcdef0bb4bba..f13bca2dd53b 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -388,6 +388,12 @@ struct hid_report_enum {
 struct hid_control_fifo {
         unsigned char dir;
         struct hid_report *report;
+        char *raw_report;
+};
+
+struct hid_output_fifo {
+        struct hid_report *report;
+        char *raw_report;
 };
 
 #define HID_CLAIMED_INPUT       1