From 97ca0712c8f2b65479649693ffe01e7358418955 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Tue, 3 Jul 2018 10:53:31 +0200 Subject: qmp: Get rid of x-oob-test command tests/qmp-test tests an out-of-band command overtaking a slow in-band command. To do that, it needs: 1. An in-band command that *reliably* takes long enough to be overtaken. 2. An out-of-band command to do the overtaking. 3. To avoid delays, a way to make the in-band command complete quickly after it was overtaken. To satisfy these needs, commit 469638f9cb3 provides the rather peculiar oob-capable QMP command x-oob-test: * With "lock": true, it waits for a global semaphore. * With "lock": false, it signals the global semaphore. To satisfy 1., the test runs x-oob-test in-band with "lock": true. To satisfy 2. and 3., it runs x-oob-test out-of-band with "lock": false. Note that waiting for a semaphore violates the rules for oob-capable commands. Running x-oob-test with "lock": true hangs the monitor until you run x-oob-test with "lock": false on another monitor (which you might not have set up). Having an externally visible QMP command that may hang the monitor is not nice. Let's apply a little more ingenuity to the problem. Idea: have an existing command block on reading a FIFO special file, unblock it by opening the FIFO for writing. For 1., use {"execute": "blockdev-add", "id": ID1, "arguments": { "driver": "blkdebug", "node-name": ID1, "config": FIFO, "image": { "driver": "null-co"}}} where ID1 is an arbitrary string, and FIFO is the name of the FIFO. For 2., use {"execute": "migrate-pause", "id": ID2, "control": {"run-oob": true}} where ID2 is a different arbitrary string. Since there's no migration to pause, the command will fail, but that's fine; instant failure is still a test of out-of-band responses overtaking in-band commands. For 3., open FIFO for writing. Drop QMP command x-oob-test. Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20180703085358.13941-6-armbru@redhat.com> [Error checking tweaked] --- qmp.c | 16 ---------------- 1 file changed, 16 deletions(-) (limited to 'qmp.c') diff --git a/qmp.c b/qmp.c index 73e46d795f..62325ac6aa 100644 --- a/qmp.c +++ b/qmp.c @@ -775,19 +775,3 @@ MemoryInfo *qmp_query_memory_size_summary(Error **errp) return mem_info; } - -static QemuSemaphore x_oob_test_sem; - -static void __attribute__((constructor)) x_oob_test_init(void) -{ - qemu_sem_init(&x_oob_test_sem, 0); -} - -void qmp_x_oob_test(bool lock, Error **errp) -{ - if (lock) { - qemu_sem_wait(&x_oob_test_sem); - } else { - qemu_sem_post(&x_oob_test_sem); - } -} -- cgit v1.2.3