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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Test that poll handlers are not re-entrant in nested aio_poll()
*
* Copyright Red Hat
*
* Poll handlers are usually level-triggered. That means they continue firing
* until the condition is reset (e.g. a virtqueue becomes empty). If a poll
* handler calls nested aio_poll() before the condition is reset, then infinite
* recursion occurs.
*
* aio_poll() is supposed to prevent this by disabling poll handlers in nested
* aio_poll() calls. This test case checks that this is indeed what happens.
*/
#include "qemu/osdep.h"
#include "block/aio.h"
#include "qapi/error.h"
typedef struct {
AioContext *ctx;
/* This is the EventNotifier that drives the test */
EventNotifier poll_notifier;
/* This EventNotifier is only used to wake aio_poll() */
EventNotifier dummy_notifier;
bool nested;
} TestData;
static void io_read(EventNotifier *notifier)
{
fprintf(stderr, "%s %p\n", __func__, notifier);
event_notifier_test_and_clear(notifier);
}
static bool io_poll_true(void *opaque)
{
fprintf(stderr, "%s %p\n", __func__, opaque);
return true;
}
static bool io_poll_false(void *opaque)
{
fprintf(stderr, "%s %p\n", __func__, opaque);
return false;
}
static void io_poll_ready(EventNotifier *notifier)
{
TestData *td = container_of(notifier, TestData, poll_notifier);
fprintf(stderr, "> %s\n", __func__);
g_assert(!td->nested);
td->nested = true;
/* Wake the following nested aio_poll() call */
event_notifier_set(&td->dummy_notifier);
/* This nested event loop must not call io_poll()/io_poll_ready() */
g_assert(aio_poll(td->ctx, true));
td->nested = false;
fprintf(stderr, "< %s\n", __func__);
}
/* dummy_notifier never triggers */
static void io_poll_never_ready(EventNotifier *notifier)
{
g_assert_not_reached();
}
static void test(void)
{
TestData td = {
.ctx = aio_context_new(&error_abort),
};
qemu_set_current_aio_context(td.ctx);
/* Enable polling */
aio_context_set_poll_params(td.ctx, 1000000, 2, 2, &error_abort);
/*
* The GSource is unused but this has the side-effect of changing the fdmon
* that AioContext uses.
*/
aio_get_g_source(td.ctx);
/* Make the event notifier active (set) right away */
event_notifier_init(&td.poll_notifier, 1);
aio_set_event_notifier(td.ctx, &td.poll_notifier, false,
io_read, io_poll_true, io_poll_ready);
/* This event notifier will be used later */
event_notifier_init(&td.dummy_notifier, 0);
aio_set_event_notifier(td.ctx, &td.dummy_notifier, false,
io_read, io_poll_false, io_poll_never_ready);
/* Consume aio_notify() */
g_assert(!aio_poll(td.ctx, false));
/*
* Run the io_read() handler. This has the side-effect of activating
* polling in future aio_poll() calls.
*/
g_assert(aio_poll(td.ctx, true));
/* The second time around the io_poll()/io_poll_ready() handler runs */
g_assert(aio_poll(td.ctx, true));
/* Run io_poll()/io_poll_ready() one more time to show it keeps working */
g_assert(aio_poll(td.ctx, true));
aio_set_event_notifier(td.ctx, &td.dummy_notifier, false,
NULL, NULL, NULL);
aio_set_event_notifier(td.ctx, &td.poll_notifier, false, NULL, NULL, NULL);
event_notifier_cleanup(&td.dummy_notifier);
event_notifier_cleanup(&td.poll_notifier);
aio_context_unref(td.ctx);
}
int main(int argc, char **argv)
{
g_test_init(&argc, &argv, NULL);
g_test_add_func("/nested-aio-poll", test);
return g_test_run();
}
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