[LTP] [PATCH v3] kernel/input: fix failure on an old kernel

[Xiao Yang <yangx.jy@cn.fujitsu.com>]

Hi Cyril,

Ping. :-)

Thanks,
Xiao Yang
On 2017/11/13 14:45, Xiao Yang wrote:
> 1) On some old kernels(e.g. v2.6.32), we always triggered the following
>     error when running input04 and input05:
>     --------------------------------------------------------------------
>     TINFO  :  Found uinput dev at /dev/uinput
>     TINFO  :  Unexpected ev type=0 code=0 value=0
>     TFAIL  :  Data received /dev/inputX
>     ---------------------------------------------------------------------
>
>     After investigation, the single EV_SYN event can be processed on an
>     old kernel.  However, the EV_SYN event handling has been modfied by
>     the following patch:
>     '4369c64c79a2("Input: Send events one packet at a time")'
>
>     The patch is designed to reduce the time taken for processing a lot of
>     events.  As a side effect, the single EV_SYN event handling depends on
>     one or more other events(e.g. EV_REL), so it should be processed
>     together with others, since this action is atomic.
>
>     Only when the number of queued events(include EV_SYN) is greater than
>     one can these events be processed.
>     Please see the kenrel code in drivers/input/input.c, as below:
>     --------------------------------------------------------------------
>     static void input_handle_event(struct input_dev *dev,
>     ...
>     if (disposition&  INPUT_FLUSH) {
>     	// num_vals: number of values queued in the current frame
>     	if (dev->num_vals>= 2)
>     		input_pass_values(dev, dev->vals, dev->num_vals);
>     		dev->num_vals = 0;
>     ...
>     --------------------------------------------------------------------
>
>     For example, steps to send an empty move and EV_SYN:
>     -----------------------------------------------------
>     send_event(fd, EV_REL, REL_X, 0);
>     send_event(fd, EV_SYN, 0, 0);
>     -----------------------------------------------------
>
>     On an old kernel(before v3.7.0), the EV_SYN/SYN_REPORT event can be
>     processed independently, so it is passed into /dev/input/eventX.
>
>     On a new kernel(since v3.7.0), the EV_SYN/SYN_REPORT event depends on
>     EV_REL/REL_X which is an empty move, so it is ignored.
>
>     We feel this failure is due to the different mechanism of processing
>     EV_SYN instead of a kernel bug, so we ignore stray sync events on older
>     kernels.
>
> 2) We move the check_event_code and check_sync_event() helpers to the
>     library so that we can use them.
>
> 3) Fix compiler warning, as below:
>     ------------------------------------------------------------------------
>     input06.c:213: warning: ‘ret’ may be used uninitialized in this function
>     ------------------------------------------------------------------------
>
> Signed-off-by: Xiao Yang<yangx.jy@cn.fujitsu.com>
> ---
>   testcases/kernel/input/input02.c      |  2 +-
>   testcases/kernel/input/input04.c      |  2 +-
>   testcases/kernel/input/input05.c      |  2 +-
>   testcases/kernel/input/input06.c      | 18 ++++--------------
>   testcases/kernel/input/input_helper.c | 34 +++++++++++++++++++++++++++++-----
>   testcases/kernel/input/input_helper.h |  4 +++-
>   6 files changed, 39 insertions(+), 23 deletions(-)
>
> diff --git a/testcases/kernel/input/input02.c b/testcases/kernel/input/input02.c
> index df3b257..6964ed7 100644
> --- a/testcases/kernel/input/input02.c
> +++ b/testcases/kernel/input/input02.c
> @@ -61,7 +61,7 @@ int main(int ac, char **av)
>   		case -1:
>   			tst_brkm(TBROK | TERRNO, cleanup, "fork() failed");
>   		default:
> -			if (no_events_queued(fd2))
> +			if (no_events_queued(fd2, 0))
>   				tst_resm(TPASS, "No data received in eventX");
>   			else
>   				tst_resm(TFAIL, "Data received in eventX");
> diff --git a/testcases/kernel/input/input04.c b/testcases/kernel/input/input04.c
> index 4b16ca7..e57b76b 100644
> --- a/testcases/kernel/input/input04.c
> +++ b/testcases/kernel/input/input04.c
> @@ -57,7 +57,7 @@ int main(int ac, char **av)
>   		case -1:
>   			tst_brkm(TBROK | TERRNO, cleanup, "fork() failed");
>   		default:
> -			if (no_events_queued(fd2))
> +			if (no_events_queued(fd2, 1))
>   				tst_resm(TPASS,
>   					"No data received in /dev/inputX");
>   			else
> diff --git a/testcases/kernel/input/input05.c b/testcases/kernel/input/input05.c
> index 5ca01d8..46b4fe8 100644
> --- a/testcases/kernel/input/input05.c
> +++ b/testcases/kernel/input/input05.c
> @@ -63,7 +63,7 @@ int main(int ac, char **av)
>   		case -1:
>   			tst_brkm(TBROK | TERRNO, cleanup, "fork() failed");
>   		default:
> -			if (no_events_queued(fd2))
> +			if (no_events_queued(fd2, 1))
>   				tst_resm(TPASS, "No data received in eventX");
>   			else
>   				tst_resm(TFAIL, "Data received in eventX");
> diff --git a/testcases/kernel/input/input06.c b/testcases/kernel/input/input06.c
> index 4c5f1a8..14141b7 100644
> --- a/testcases/kernel/input/input06.c
> +++ b/testcases/kernel/input/input06.c
> @@ -115,11 +115,6 @@ static int check_event(struct input_event *iev, int event, int code, int value)
>   	return iev->type == event&&  iev->code == code&&  iev->value == value;
>   }
>
> -static int check_event_code(struct input_event *iev, int event, int code)
> -{
> -	return iev->type == event&&  iev->code == code;
> -}
> -
>   static void read_events(void)
>   {
>   	int rd = read(fd2, events, sizeof(events));
> @@ -151,11 +146,6 @@ static struct input_event *next_event(void)
>   	return&events[ev_iter++];
>   }
>
> -static int check_sync_event(void)
> -{
> -	return check_event_code(next_event(), EV_SYN, SYN_REPORT);
> -}
> -
>   static int parse_autorepeat_config(struct input_event *iev)
>   {
>   	if (!check_event_code(iev, EV_REP, REP_DELAY)) {
> @@ -177,13 +167,13 @@ static int parse_key(struct input_event *iev)
>   {
>   	int autorep_count = 0;
>
> -	if (!check_event(iev, EV_KEY, KEY_X, 1) || !check_sync_event()) {
> +	if (!check_event(iev, EV_KEY, KEY_X, 1) || !check_sync_event(next_event())) {
>   		tst_resm(TFAIL, "Didn't get expected key press for KEY_X");
>   		return 0;
>   	}
>
>   	iev = next_event();
> -	while (check_event(iev, EV_KEY, KEY_X, 2)&&  check_sync_event()) {
> +	while (check_event(iev, EV_KEY, KEY_X, 2)&&  check_sync_event(next_event())) {
>   		autorep_count++;
>   		iev = next_event();
>   	}
> @@ -195,7 +185,7 @@ static int parse_key(struct input_event *iev)
>   		return 0;
>   	}
>
> -	if (!check_event(iev, EV_KEY, KEY_X, 0) || !check_sync_event()) {
> +	if (!check_event(iev, EV_KEY, KEY_X, 0) || !check_sync_event(next_event())) {
>   		tst_resm(TFAIL,
>   			 "Didn't get expected key release for KEY_X");
>   		return 0;
> @@ -210,7 +200,7 @@ static int parse_key(struct input_event *iev)
>   static int check_events(void)
>   {
>   	struct input_event *iev;
> -	int ret;
> +	int ret = 0;
>   	int rep_config_done = 0;
>   	int rep_keys_done = 0;
>
> diff --git a/testcases/kernel/input/input_helper.c b/testcases/kernel/input/input_helper.c
> index 08fa81c..13a6cd8 100644
> --- a/testcases/kernel/input/input_helper.c
> +++ b/testcases/kernel/input/input_helper.c
> @@ -229,21 +229,45 @@ void destroy_device(int fd)
>   		unload_uinput();
>   }
>
> -int no_events_queued(int fd)
> +int check_event_code(struct input_event *iev, int event, int code)
> +{
> +	return iev->type == event&&  iev->code == code;
> +}
> +
> +int check_sync_event(struct input_event *iev)
> +{
> +	return check_event_code(iev, EV_SYN, SYN_REPORT);
> +}
> +
> +/*
> + * the value of stray_sync_event:
> + * 0: EV_SYN/SYN_REPORT events should not be received in /dev/input/eventX
> + * 1: EV_SYN/SYN_REPORT events may be received in /dev/input/eventX
> + * On an old kernel(before v3.7.0), EV_SYN/SYN_REPORT events are always
> + * received even though we send empty moves.
> + */
> +int no_events_queued(int fd, int stray_sync_event)
>   {
>   	struct pollfd fds = {.fd = fd, .events = POLLIN};
> -	int ret, res;
> +	int ret, res, sync_event_ignored;
>   	struct input_event ev;
>
> +	if (tst_kvercmp(3, 7, 0)<  0&&  stray_sync_event)
> +		sync_event_ignored = 1;
> +
>   	ret = poll(&fds, 1, 30);
>
>   	if (ret>  0) {
>   		res = read(fd,&ev, sizeof(ev));
>
>   		if (res == sizeof(ev)) {
> -			tst_resm(TINFO,
> -			         "Unexpected ev type=%i code=%i value=%i",
> -			         ev.type, ev.code, ev.value);
> +			if (sync_event_ignored&&  check_sync_event(&ev)) {
> +				ret = 0;
> +			} else {
> +				tst_resm(TINFO,
> +					 "Unexpected ev type=%i code=%i value=%i",
> +					 ev.type, ev.code, ev.value);
> +			}
>   		}
>   	}
>
> diff --git a/testcases/kernel/input/input_helper.h b/testcases/kernel/input/input_helper.h
> index 9b85dc9..7f61be1 100644
> --- a/testcases/kernel/input/input_helper.h
> +++ b/testcases/kernel/input/input_helper.h
> @@ -29,6 +29,8 @@ int open_uinput(void);
>   void create_device(int fd);
>   void setup_mouse_events(int fd);
>   void destroy_device(int fd);
> -int no_events_queued(int fd);
> +int check_event_code(struct input_event *iev, int event, int code);
> +int check_sync_event(struct input_event *iev);
> +int no_events_queued(int fd, int stray_sync_event);
>
>   #endif /* INPUT_HELPER_H */