On Fri, 3 May 2013, Benjamin Tissoires wrote:
> Thanks for reporting it.
>
> Jiri, we had a similar bug in the RH bugzilla:
> https://bugzilla.redhat.com/show_bug.cgi?id=958935
>
> Are these two reports potentially fixed by your patch "HID: protect
> hid_debug_list" (https://patchwork.kernel.org/patch/2453931/)
> If so, maybe we should send it to stable as well...
I actually believe this bug is *introduced* by that patch :) All the
reports were with the kernel containing it, right?
Does the patch below fix it, please?
drivers/hid/hid-core.c | 2 +-
drivers/hid/hid-debug.c | 14 ++++++++------
include/linux/hid.h | 2 +-
3 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 1e51159..264f550 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2342,7 +2342,7 @@ struct hid_device *hid_allocate_device(void)
init_waitqueue_head(&hdev->debug_wait);
INIT_LIST_HEAD(&hdev->debug_list);
- mutex_init(&hdev->debug_list_lock);
+ spin_lock_init(&hdev->debug_list_lock);
sema_init(&hdev->driver_lock, 1);
sema_init(&hdev->driver_input_lock, 1);
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 7e56cb3..572572c 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -580,14 +580,14 @@ void hid_debug_event(struct hid_device *hdev, char *buf)
int i;
struct hid_debug_list *list;
- mutex_lock(&hdev->debug_list_lock);
+ spin_lock(&hdev->debug_list_lock);
list_for_each_entry(list, &hdev->debug_list, node) {
for (i = 0; i < strlen(buf); i++)
list->hid_debug_buf[(list->tail + i) %
HID_DEBUG_BUFSIZE] =
buf[i];
list->tail = (list->tail + i) % HID_DEBUG_BUFSIZE;
}
- mutex_unlock(&hdev->debug_list_lock);
+ spin_unlock(&hdev->debug_list_lock);
wake_up_interruptible(&hdev->debug_wait);
}
@@ -977,6 +977,7 @@ static int hid_debug_events_open(struct inode *inode,
struct file *file)
{
int err = 0;
struct hid_debug_list *list;
+ unsigned long flags;
if (!(list = kzalloc(sizeof(struct hid_debug_list), GFP_KERNEL))) {
err = -ENOMEM;
@@ -992,9 +993,9 @@ static int hid_debug_events_open(struct inode *inode,
struct file *file)
file->private_data = list;
mutex_init(&list->read_mutex);
- mutex_lock(&list->hdev->debug_list_lock);
+ spin_lock_irqsave(&list->hdev->debug_list_lock, flags);
list_add_tail(&list->node, &list->hdev->debug_list);
- mutex_unlock(&list->hdev->debug_list_lock);
+ spin_unlock_irqrestore(&list->hdev->debug_list_lock, flags);
out:
return err;
@@ -1088,10 +1089,11 @@ static unsigned int hid_debug_events_poll(struct file
*file, poll_table *wait)
static int hid_debug_events_release(struct inode *inode, struct file *file)
{
struct hid_debug_list *list = file->private_data;
+ unsigned long flags;
- mutex_lock(&list->hdev->debug_list_lock);
+ spin_lock_irqsave(&list->hdev->debug_list_lock, flags);
list_del(&list->node);
- mutex_unlock(&list->hdev->debug_list_lock);
+ spin_unlock_irqrestore(&list->hdev->debug_list_lock, flags);
kfree(list->hid_debug_buf);
kfree(list);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index af1b86d..0c48991 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -515,7 +515,7 @@ struct hid_device {
/* device report descriptor */
struct dentry *debug_rdesc;
struct dentry *debug_events;
struct list_head debug_list;
- struct mutex debug_list_lock;
+ spinlock_t debug_list_lock;
wait_queue_head_t debug_wait;
};
--
Jiri Kosina
SUSE Labs
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