diff mbox

[0/4] HID: debugfs rework

Message ID alpine.LNX.2.00.1304171041070.31201@pobox.suse.cz
State New, archived
Delegated to: Jiri Kosina
Headers show

Commit Message

Jiri Kosina April 17, 2013, 5:44 p.m. UTC
On Wed, 17 Apr 2013, Benjamin Tissoires wrote:

> Hi Jiri,
> 
> This is a small rework of the HID debugfs.
> I encountered a problem with multitouch devices: they have too much usages to
> fit into the fixed size output buffer of 512.
> So I digg a little, and end up with those 4 patches.

Hi Benjamin,

thanks, I will look into it and see whether I would be able to apply it 
still for 3.10 merge window.

I also have a locking fix for HID-debugfs which I am going to apply 
shortly, but I am travelling this week, so I am in a bit degraded mode.

For reference, locking fix below.



From: Jiri Kosina <jkosina@suse.cz>
Subject: [PATCH] HID: protect hid_debug_list

Accesses to hid_device->hid_debug_list are not serialized properly, which
could result in SMP concurrency issues when HID debugfs events are accessesed
by multiple userspace processess.

Serialize all the list operations by a mutex.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
 drivers/hid/hid-core.c  | 1 +
 drivers/hid/hid-debug.c | 6 ++++++
 include/linux/hid.h     | 1 +
 3 files changed, 8 insertions(+)

Comments

Benjamin Tissoires April 18, 2013, 7:52 a.m. UTC | #1
On 04/17/2013 07:44 PM, Jiri Kosina wrote:
> On Wed, 17 Apr 2013, Benjamin Tissoires wrote:
> 
>> Hi Jiri,
>>
>> This is a small rework of the HID debugfs.
>> I encountered a problem with multitouch devices: they have too much usages to
>> fit into the fixed size output buffer of 512.
>> So I digg a little, and end up with those 4 patches.
> 
> Hi Benjamin,
> 
> thanks, I will look into it and see whether I would be able to apply it 
> still for 3.10 merge window.

Thanks. I think patches 1 and 2 of this series are pretty straightforward.
Patches 3 and 4 will maybe require a little bit more attention.

I don't mind if it's postponed to 3.11 (given the long time this has
been broken for devices with big reports).
I just need to access HID debugfs for hid-replay when hidraw does not
send anything. But as I'm also willing to use hid-replay with current
kernels, I still need a way to use the best option (hidraw or hid
debugfs) for current kernels.

> 
> I also have a locking fix for HID-debugfs which I am going to apply 
> shortly, but I am travelling this week, so I am in a bit degraded mode.
> 
> For reference, locking fix below.
> 
> 
> 
> From: Jiri Kosina <jkosina@suse.cz>
> Subject: [PATCH] HID: protect hid_debug_list
> 
> Accesses to hid_device->hid_debug_list are not serialized properly, which
> could result in SMP concurrency issues when HID debugfs events are accessesed

s/accessesed/accessed ?

> by multiple userspace processess.

s/processess/processes ?

> 
> Serialize all the list operations by a mutex.
> 
> Reported-by: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

I also have a patch regarding forcing hidraw output even if raw_event
returns > 0, but I'll send it over a new thread. This thread will start
to be quite complicate to follow otherwise... :)

Cheers,
Benjamin
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diff mbox

Patch

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 1129f49..e3b7123 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2347,6 +2347,7 @@  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);
 	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 933fff0..3337261 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -580,12 +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);
 	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);
 
 	wake_up_interruptible(&hdev->debug_wait);
 }
@@ -960,7 +962,9 @@  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);
 	list_add_tail(&list->node, &list->hdev->debug_list);
+	mutex_unlock(&list->hdev->debug_list_lock);
 
 out:
 	return err;
@@ -1055,7 +1059,9 @@  static int hid_debug_events_release(struct inode *inode, struct file *file)
 {
 	struct hid_debug_list *list = file->private_data;
 
+	mutex_lock(&list->hdev->debug_list_lock);
 	list_del(&list->node);
+	mutex_unlock(&list->hdev->debug_list_lock);
 	kfree(list->hid_debug_buf);
 	kfree(list);
 
diff --git a/include/linux/hid.h b/include/linux/hid.h
index b7b5ff2..af1b86d 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -515,6 +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;
 	wait_queue_head_t debug_wait;
 };