xl: do not continue in the child and exec xenconsole in the parent
Currenctly console_autoconnect spawns a child that continues building
the domain while the parent exec's xenconsole; this patch inverts the
logic.
As a consequence autoconnect_console needs to be called twice: once for
pv guests at the beginning and once for hvm guests at the end.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
diff -r 00ef2205e0bc tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c Thu Aug 26 17:04:25 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.c Thu Aug 26 17:27:56 2010 +0100
@@ -1066,39 +1066,20 @@ static void *xrealloc(void *ptr, size_t
return r;
}
-static int autoconnect_console(int hvm)
+static pid_t autoconnect_console(void)
{
- int status, options;
- pid_t pid, r;
-
- /*
- * Fork for xenconsole. We exec xenconsole in the foreground
- * process allowing it to retain the tty. xl continues in the
- * child. The xenconsole client uses a xenstore watch to wait for
- * the console to be setup so there is no race.
- */
+ pid_t pid;
+
pid = fork();
if (pid < 0) {
perror("unable to fork xenconsole");
return ERROR_FAIL;
- } else if (pid == 0)
- return 0;
-
- /*
- * In the PV case we only catch failure of the create process, in
- * the HVM case we also wait for the creation process to be
- * completed so that the stubdom is already up and running and we
- * can connect to it.
- */
- if (hvm)
- options = 0;
- else
- options = WNOHANG;
+ } else if (pid > 0)
+ return pid;
+
+ libxl_ctx_postfork(&ctx);
+
sleep(1);
- r = waitpid(pid, &status, options);
- if (r > 0 && WIFEXITED(status) && WEXITSTATUS(status) != 0)
- _exit(WEXITSTATUS(status));
-
libxl_primary_console_exec(&ctx, domid);
/* Do not return. xl continued in child process */
fprintf(stderr, "Unable to attach console\n");
@@ -1254,6 +1235,8 @@ static int create_domain(struct domain_c
int config_len = 0;
int restore_fd = -1;
struct save_file_header hdr;
+ pid_t child_console_pid = -1;
+ int status = 0;
memset(&d_config, 0x00, sizeof(d_config));
memset(&dm_info, 0x00, sizeof(dm_info));
@@ -1399,18 +1382,12 @@ start:
goto error_out;
}
- if (dom_info->console_autoconnect) {
- ret = autoconnect_console(d_config.c_info.hvm);
- if (ret)
+ if (dom_info->console_autoconnect && !d_config.c_info.hvm) {
+ child_console_pid = autoconnect_console();
+ if (child_console_pid < 0)
goto error_out;
}
- /*
- * Do not attempt to reconnect if we come round again due to a
- * guest reboot -- the stdin/out will be disconnected by then.
- */
- dom_info->console_autoconnect = 0;
-
ret = libxl_run_bootloader(&ctx, &d_config.b_info, d_config.num_disks > 0
? &d_config.disks[0] : NULL, domid);
if (ret) {
fprintf(stderr, "failed to run bootloader: %d\n", ret);
@@ -1492,6 +1469,12 @@ start:
for (i = 0; i < d_config.num_pcidevs; i++)
libxl_device_pci_add(&ctx, domid, &d_config.pcidevs[i]);
+ if (dom_info->console_autoconnect && d_config.c_info.hvm) {
+ child_console_pid = autoconnect_console();
+ if (child_console_pid < 0)
+ goto error_out;
+ }
+
if (!paused)
libxl_domain_unpause(&ctx, domid);
@@ -1506,7 +1489,6 @@ start:
child1 = libxl_fork(&ctx);
if (child1) {
- int status;
for (;;) {
got_child = waitpid(child1, &status, 0);
if (got_child == child1) break;
@@ -1523,7 +1505,8 @@ start:
ret = ERROR_FAIL;
goto error_out;
}
- return domid; /* caller gets success in parent */
+ ret = domid;
+ goto waitpid_out;
}
rc = libxl_ctx_postfork(&ctx);
@@ -1599,6 +1582,13 @@ start:
libxl_free_waiter(w2);
free(w1);
free(w2);
+
+ /*
+ * Do not attempt to reconnect if we come round again
due to a
+ * guest reboot -- the stdin/out will be disconnected
by then.
+ */
+ dom_info->console_autoconnect = 0;
+
/*
* XXX FIXME: If this sleep is not there then domain
* re-creation fails sometimes.
@@ -1635,6 +1625,9 @@ out:
free(config_data);
+waitpid_out:
+ if (child_console_pid > 0 && waitpid(child_console_pid, &status, 0) < 0 &&
errno == EINTR)
+ goto waitpid_out;
return ret;
}
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