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Kernel: Fix timeout support in select

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The scheduler expects m_select_timeout to act as a deadline. That is, it
should contain the time that a task should wake at -- but we were
directly copying the time from userspace, which meant that it always
returned virtually immediately.

At the same time, fix CEventLoop to not rely on the broken select behavior
by subtracting the current time from the time of the nearest timer.
This commit is contained in:
Robin Burchell 2019-05-18 02:00:01 +02:00 • committed by Andreas Kling
parent 8f3022b5c1
commit df74a9222f
4 changed files with 40 additions and 15 deletions
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11
LibCore/CEventLoop.cpp
View file

@ -14,6 +14,7 @@
#include <LibC/errno.h>
#include <LibC/string.h>
#include <LibC/stdlib.h>
#include <AK/Time.h>
//#define CEVENTLOOP_DEBUG
//#define DEFERRED_INVOKE_DEBUG
@ -179,18 +180,22 @@ void CEventLoop::wait_for_event()
queued_events_is_empty = m_queued_events.is_empty();
}
timeval now;
struct timeval timeout = { 0, 0 };
if (!s_timers->is_empty() && queued_events_is_empty)
if (!s_timers->is_empty() && queued_events_is_empty) {
gettimeofday(&now, nullptr);
get_next_timer_expiration(timeout);
AK::timeval_sub(&timeout, &now, &timeout);
}
int rc = select(max_fd + 1, &rfds, &wfds, nullptr, (queued_events_is_empty && s_timers->is_empty()) ? nullptr : &timeout);
if (rc < 0) {
ASSERT_NOT_REACHED();
}
timeval now;
if (!s_timers->is_empty())
if (!s_timers->is_empty()) {
gettimeofday(&now, nullptr);
}
for (auto& it : *s_timers) {
auto& timer = *it.value;