linux-kernel - Re: [PATCH] Input: evdev: fix queueing of SYN_DROPPED event for EVIOCG[type] IOCTL case

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Date:   Wed, 14 Dec 2016 23:54:43 +0530
From:   Aniroop Mathur <aniroop.mathur@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Aniroop Mathur <a.mathur@...sung.com>,
        SAMUEL SEQUEIRA <s.samuel@...sung.com>,
        Rahul Mahale <r.mahale@...sung.com>
Subject: Re: [PATCH] Input: evdev: fix queueing of SYN_DROPPED event for
 EVIOCG[type] IOCTL case

Hello Mr. Torokhov,

Would you kindly update about this patch?
Thanks!

Best Regards,
Aniroop Mathur


On Fri, Nov 25, 2016 at 1:41 AM, Aniroop Mathur <a.mathur@...sung.com> wrote:
> Currently, when EVIOCG[type] ioctl call is issued and bits_to_user fails,
> then SYN_DROPPED event is inserted in the event queue always.
>
> However, it is not compulsory that some events are flushed out on every
> EVIOCG[type] ioctl call like in case of empty event queue and in case when
> EVIOCG[type] ioctl is issued for say A type of events but event queue does
> not have any A type of events but some other type of events.
>
> Therefore, insert SYN_DROPPED event only when some events have been flushed
> out from event queue plus bits_to_user fails.
>
> Signed-off-by: Aniroop Mathur <a.mathur@...sung.com>
> ---
>  drivers/input/evdev.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index e9ae3d5..f8b295e 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -108,9 +108,11 @@ static bool __evdev_is_filtered(struct evdev_client *client,
>  }
>
>  /* flush queued events of type @type, caller must hold client->buffer_lock */
> -static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
> +static unsigned int __evdev_flush_queue(struct evdev_client *client,
> +                                       unsigned int type)
>  {
>         unsigned int i, head, num;
> +       unsigned int drop_count = 0;
>         unsigned int mask = client->bufsize - 1;
>         bool is_report;
>         struct input_event *ev;
> @@ -129,9 +131,11 @@ static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
>
>                 if (ev->type == type) {
>                         /* drop matched entry */
> +                       drop_count++;
>                         continue;
>                 } else if (is_report && !num) {
>                         /* drop empty SYN_REPORT groups */
> +                       drop_count++;
>                         continue;
>                 } else if (head != i) {
>                         /* move entry to fill the gap */
> @@ -151,6 +155,7 @@ static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
>         }
>
>         client->head = head;
> +       return drop_count;
>  }
>
>  static void __evdev_queue_syn_dropped(struct evdev_client *client)
> @@ -920,6 +925,7 @@ static int evdev_handle_get_val(struct evdev_client *client,
>         int ret;
>         unsigned long *mem;
>         size_t len;
> +       unsigned int drop_count = 0;
>
>         len = BITS_TO_LONGS(maxbit) * sizeof(unsigned long);
>         mem = kmalloc(len, GFP_KERNEL);
> @@ -933,12 +939,12 @@ static int evdev_handle_get_val(struct evdev_client *client,
>
>         spin_unlock(&dev->event_lock);
>
> -       __evdev_flush_queue(client, type);
> +       drop_count = __evdev_flush_queue(client, type);
>
>         spin_unlock_irq(&client->buffer_lock);
>
>         ret = bits_to_user(mem, maxbit, maxlen, p, compat);
> -       if (ret < 0)
> +       if (ret < 0 && drop_count > 0)
>                 evdev_queue_syn_dropped(client);
>
>         kfree(mem);
> --
> 2.6.2
>