Re: [libvirt] [PATCH 0/4] vbox: address thread-safety issues.
On Wed, 2016-09-28 at 13:41 -0400, Dawid Zamirski wrote:
This patch series solves (at least in my testing) vbox driver
thread-safety issues that were also outlined on libvirt-users ML [1]
and I was affected with.
Just to give a more practical context on the issue I'm trying to solve
with this series, given this simple example code:
=======================
#define _GNU_SOURCE
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>
const char *xml_tmpl = "<?xml version=\"1.0\"?>"
"<domain type=\"vbox\">"
" <name>%s</name>"
" <memory unit=\"MiB\">3072</memory>"
" <vcpu>2</vcpu>"
" <os>"
" <type arch=\"x86_64\">hvm</type>"
" <boot dev=\"cdrom\"/>"
" <boot dev=\"hd\"/>"
" </os>"
" <features>"
" <acpi/>"
" <apic/>"
" <pae/>"
" </features>"
" <cpu mode=\"host-model\"/>"
" <devices>"
" <graphics type=\"rdp\" autoport=\"yes\"
multiUser=\"yes\"></graphics>"
" <video primary=\"yes\">"
" <model type=\"vbox\" vram=\"24576\"
heads=\"1\"></model>"
" </video>"
" </devices>"
"</domain>";
int main(int argc, char *argv[]) {
virConnectPtr conn;
char *vm_xml;
int ret = 0;
if (argc != 2) {
fprintf(stderr, "Please specify VM name as first argument\n");
return 1;
}
conn = virConnectOpen("vbox:///session");
if (conn == NULL) {
fprintf(stderr, "Failed to open connection to
vbox:///session\n");
return 1;
} else {
printf("Connected to vbox successfully...\n");
}
printf("Sleeping for 5s...\n");
sleep(5);
if (asprintf(&vm_xml, xml_tmpl, argv[1]) == -1) {
fprintf(stderr, "Failed to allocate memory for VM XML
definition string\n");
ret = 1;
goto cleanup;
}
printf("Defining domain...\n");
virDomainPtr dom = virDomainDefineXML(conn, vm_xml);
if (dom == NULL) {
const char *error = virGetLastErrorMessage();
fprintf(stderr, "Failed to define domain: %s\n", error);
ret = 1;
goto cleanup;
}
printf("Domain defined successfully.\n");
sleep(1);
printf("Undefining domain...\n");
if (virDomainUndefine(dom) == -1) {
const char *error = virGetLastErrorMessage();
fprintf(stderr, "Failed to undefine domain %s\n", error);
fprintf(stderr, "This may require cleanup of the VBOX home dir
from stale template files\n");
ret = 1;
goto cleanup;
}
printf("Domain undefined successfully.\n");
cleanup:
printf("Closing vbox connection...\n");
virConnectClose(conn);
printf("Done\n");
free(vm_xml);
vm_xml = NULL;
return ret;
}
================================
After compiling (to say, vbox-test):
1. ./vbox-test vm1 # creates/destroys vbox VM named "vm1"
2. while #1 is sleeping, ./vbox-test vm2 # will attempt to do the same
for "vm2" by spawning concurrent vbox connection.
3. result: the 2nd process will segfault libvirtd
with those patches applied both succeed as expected.
Regards,
Dawid