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Recover from bad input event timestamps from the kernel.

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This can happen due to a race when the input device is
opened or if the kernel happens to be missing the required
Android patches to set the timestamp correctly.

Bug: 7291243
Change-Id: If4319440eaff2889147c86296abd39efc5664346
This commit is contained in:
Jeff Brown
2012-10-05 17:59:56 -07:00
parent f948500239
commit f33b2b2b24
2 changed files with 37 additions and 2 deletions
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34
services/input/EventHub.cpp
View File

@@ -787,6 +787,40 @@ size_t EventHub::getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSiz
event->when = nsecs_t(iev.time.tv_sec) * 1000000000LL
+ nsecs_t(iev.time.tv_usec) * 1000LL;
ALOGV("event time %lld, now %lld", event->when, now);
// Bug 7291243: Add a guard in case the kernel generates timestamps
// that appear to be far into the future because they were generated
// using the wrong clock source.
//
// This can happen because when the input device is initially opened
// it has a default clock source of CLOCK_REALTIME. Any input events
// enqueued right after the device is opened will have timestamps
// generated using CLOCK_REALTIME. We later set the clock source
// to CLOCK_MONOTONIC but it is already too late.
//
// Invalid input event timestamps can result in ANRs, crashes and
// and other issues that are hard to track down. We must not let them
// propagate through the system.
//
// Log a warning so that we notice the problem and recover gracefully.
if (event->when >= now + 10 * 1000000000LL) {
// Double-check. Time may have moved on.
nsecs_t time = systemTime(SYSTEM_TIME_MONOTONIC);
if (event->when > time) {
ALOGW("An input event from %s has a timestamp that appears to "
"have been generated using the wrong clock source "
"(expected CLOCK_MONOTONIC): "
"event time %lld, current time %lld, call time %lld. "
"Using current time instead.",
device->path.string(), event->when, time, now);
event->when = time;
} else {
ALOGV("Event time is ok but failed the fast path and required "
"an extra call to systemTime: "
"event time %lld, current time %lld, call time %lld.",
event->when, time, now);
}
}
#else
event->when = now;
#endif

5
services/input/InputReader.cpp
View File

@@ -956,8 +956,9 @@ void InputDevice::process(const RawEvent* rawEvents, size_t count) {
size_t numMappers = mMappers.size();
for (const RawEvent* rawEvent = rawEvents; count--; rawEvent++) {
#if DEBUG_RAW_EVENTS
ALOGD("Input event: device=%d type=0x%04x code=0x%04x value=0x%08x",
rawEvent->deviceId, rawEvent->type, rawEvent->code, rawEvent->value);
ALOGD("Input event: device=%d type=0x%04x code=0x%04x value=0x%08x when=%lld",
rawEvent->deviceId, rawEvent->type, rawEvent->code, rawEvent->value,
rawEvent->when);
#endif
if (mDropUntilNextSync) {