[LTP] [PATCH] input_common.h: Add retry loop for event device

[LTP] [PATCH] input_common.h: Add retry loop for event device

[Edward Liaw via ltp]

Android has a delay between the entry in /proc/bus/input/devices and the
path /dev/input/eventN becoming accessible.  Add a 1s retry loop to
account for this.

Signed-off-by: Edward Liaw <edliaw@google.com>
---
 testcases/kernel/input/input_common.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/input/input_common.h b/testcases/kernel/input/input_common.h
index 0ac1624b3..06fba753e 100644
--- a/testcases/kernel/input/input_common.h
+++ b/testcases/kernel/input/input_common.h
@@ -29,9 +29,12 @@ static inline int open_event_device(void)
 			memset(path, 0, sizeof(path));
 			snprintf(path, sizeof(path), "/dev/input/%s", device);
 
-			if (!access(path, F_OK)) {
-				tst_res(TINFO, "Found event device: %s", path);
-				break;
+			for (int i = 100 ; i > 0 ; i--) {
+				if (!access(path, F_OK)) {
+					tst_res(TINFO, "Found event device: %s", path);
+					break;
+				}
+				usleep(10000);
 			}
 		}
 
-- 
2.48.1.711.g2feabab25a-goog


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Re: [LTP] [PATCH] input_common.h: Add retry loop for event device

[Cyril Hrubis]

Hi!
> +			for (int i = 100 ; i > 0 ; i--) {
> +				if (!access(path, F_OK)) {
> +					tst_res(TINFO, "Found event device: %s", path);
> +					break;
> +				}
> +				usleep(10000);

We do have a TST_RETRY_FUNC() in include/tst_common.h that is slightly
smarter than this loop and also properly scales the timeout on slow
devices automaticaly. So this should be:

	if (!TST_RETRY_FUNC(access(path, F_OK), TST_RETVAL_NULL)) {
		tst_res(TINFO, "Found event device: %s", path);
		break;
	}

-- 
Cyril Hrubis
chrubis@suse.cz

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