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] --- qapi/misc.json | 18 ------------------ 1 file changed, 18 deletions(-) (limited to 'qapi/misc.json') diff --git a/qapi/misc.json b/qapi/misc.json index 74cd97f237..f1860418e8 100644 --- a/qapi/misc.json +++ b/qapi/misc.json @@ -3472,24 +3472,6 @@ { 'event': 'COMMAND_DROPPED' , 'data': { 'id': 'any', 'reason': 'CommandDropReason' } } -## -# @x-oob-test: -# -# Test OOB functionality. When sending this command with lock=true, -# it'll try to hang the dispatcher. When sending it with lock=false, -# it'll try to notify the locked thread to continue. Note: it should -# only be used by QMP test program rather than anything else. -# -# Since: 2.12 -# -# Example: -# -# { "execute": "x-oob-test", -# "arguments": { "lock": true } } -## -{ 'command': 'x-oob-test', 'data' : { 'lock': 'bool' }, - 'allow-oob': true } - ## # @set-numa-node: # -- cgit v1.2.3