Fei Li <f...@suse.com> writes:
> On 10/11/2018 09:13 PM, Markus Armbruster wrote:
>> Fei Li <f...@suse.com> writes:
>>
>>> Add a new Error parameter for vnc_display_init() to handle errors
>>> in its caller: vnc_init_func(), just like vnc_display_open() does.
>>> And let the call trace propagate the Error.
>>>
>>> Besides, make vnc_start_worker_thread() return a bool to indicate
>>> whether it succeeds instead of returning nothing.
>>>
>>> Signed-off-by: Fei Li <f...@suse.com>
>>> Reviewed-by: Fam Zheng <f...@redhat.com>
>>> ---
>>> include/ui/console.h | 2 +-
>>> ui/vnc-jobs.c | 9 ++++++---
>>> ui/vnc-jobs.h | 2 +-
>>> ui/vnc.c | 12 +++++++++---
>>> 4 files changed, 17 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/include/ui/console.h b/include/ui/console.h
>>> index fb969caf70..c17803c530 100644
>>> --- a/include/ui/console.h
>>> +++ b/include/ui/console.h
>>> @@ -453,7 +453,7 @@ void qemu_display_early_init(DisplayOptions *opts);
>>> void qemu_display_init(DisplayState *ds, DisplayOptions *opts);
>>> /* vnc.c */
>>> -void vnc_display_init(const char *id);
>>> +void vnc_display_init(const char *id, Error **errp);
>>> void vnc_display_open(const char *id, Error **errp);
>>> void vnc_display_add_client(const char *id, int csock, bool skipauth);
>>> int vnc_display_password(const char *id, const char *password);
>>> diff --git a/ui/vnc-jobs.c b/ui/vnc-jobs.c
>>> index 929391f85d..8807d7217c 100644
>>> --- a/ui/vnc-jobs.c
>>> +++ b/ui/vnc-jobs.c
>>> @@ -331,15 +331,18 @@ static bool vnc_worker_thread_running(void)
>>> return queue; /* Check global queue */
>>> }
>>> -void vnc_start_worker_thread(void)
>>> +bool vnc_start_worker_thread(Error **errp)
>>> {
>>> VncJobQueue *q;
>>> - if (vnc_worker_thread_running())
>>> - return ;
>>> + if (vnc_worker_thread_running()) {
>>> + goto out;
>>> + }
>>> q = vnc_queue_init();
>>> qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
>>> QEMU_THREAD_DETACHED);
>>> queue = q; /* Set global queue */
>>> +out:
>>> + return true;
>>> }
>> This function cannot fail. Why convert it to Error, and complicate its
>> caller?
> [Issue1]
> Actually, this is to pave the way for patch 7/7, in case
> qemu_thread_create() fails.
> Patch 7/7 is long enough, thus I wrote the patch 1/2/3 separately to mainly
> connects the broken errp for callers who initially have the errp.
>
> [I am back... If the other codes in this patches be squashed, maybe
> merge [Issue1]
> into patch 7/7 looks more intuitive.]
>>> diff --git a/ui/vnc-jobs.h b/ui/vnc-jobs.h
>>> index 59f66bcc35..14640593db 100644
>>> --- a/ui/vnc-jobs.h
>>> +++ b/ui/vnc-jobs.h
>>> @@ -37,7 +37,7 @@ void vnc_job_push(VncJob *job);
>>> void vnc_jobs_join(VncState *vs);
>>> void vnc_jobs_consume_buffer(VncState *vs);
>>> -void vnc_start_worker_thread(void);
>>> +bool vnc_start_worker_thread(Error **errp);
>>> /* Locks */
>>> static inline int vnc_trylock_display(VncDisplay *vd)
>>> diff --git a/ui/vnc.c b/ui/vnc.c
>>> index cf221c83cc..f3806e76db 100644
>>> --- a/ui/vnc.c
>>> +++ b/ui/vnc.c
>>> @@ -3205,7 +3205,7 @@ static const DisplayChangeListenerOps dcl_ops = {
>>> .dpy_cursor_define = vnc_dpy_cursor_define,
>>> };
>>> -void vnc_display_init(const char *id)
>>> +void vnc_display_init(const char *id, Error **errp)
>>> {
>>> VncDisplay *vd;
>>>
>> if (vnc_display_find(id) != NULL) {
>> return;
>> }
>> vd = g_malloc0(sizeof(*vd));
>>
>> vd->id = strdup(id);
>> QTAILQ_INSERT_TAIL(&vnc_displays, vd, next);
>>
>> QTAILQ_INIT(&vd->clients);
>> vd->expires = TIME_MAX;
>>
>> if (keyboard_layout) {
>> trace_vnc_key_map_init(keyboard_layout);
>> vd->kbd_layout = init_keyboard_layout(name2keysym,
>> keyboard_layout);
>> } else {
>> vd->kbd_layout = init_keyboard_layout(name2keysym, "en-us");
>> }
>>
>> if (!vd->kbd_layout) {
>> exit(1);
>>
>> Uh, init_keyboard_layout() reports errors to stderr, and the exit(1)
>> here makes them fatal. Okay before this patch, but inappropriate
>> afterwards. I'm afraid you have to convert init_keyboard_layout() to
>> Error first.
> [Issue2]
> Right. But I notice the returned kbd_layout_t *kbd_layout is a static
> value and also
> will be used by others, how about passing the errp parameter to
> init_keyboard_layout()
> as follows? And for its other callers, just pass NULL.
>
> @@ -3222,13 +3222,13 @@ void vnc_display_init(const char *id, Error **errp)
>
> if (keyboard_layout) {
> trace_vnc_key_map_init(keyboard_layout);
> - vd->kbd_layout = init_keyboard_layout(name2keysym, keyboard_layout);
> + vd->kbd_layout = init_keyboard_layout(name2keysym, keyboard_layout,
> errp);
> } else {
> - vd->kbd_layout = init_keyboard_layout(name2keysym, "en-us");
> + vd->kbd_layout = init_keyboard_layout(name2keysym, "en-us", errp);
> }
>
> if (!vd->kbd_layout) {
> - exit(1);
> + return;
> }
Sounds good to me, except you should pass &error_fatal instead of NULL
to preserve "report error and exit" semantics.
>>
>> }
>>
>> vd->share_policy = VNC_SHARE_POLICY_ALLOW_EXCLUSIVE;
>>> @@ -3235,7 +3235,9 @@ void vnc_display_init(const char *id)
>>> vd->connections_limit = 32;
>>> qemu_mutex_init(&vd->mutex);
>>> - vnc_start_worker_thread();
>>> + if (!vnc_start_worker_thread(errp)) {
>>> + return;
>>> + }
>>> vd->dcl.ops = &dcl_ops;
>>> register_displaychangelistener(&vd->dcl);
>>> @@ -4079,7 +4081,11 @@ int vnc_init_func(void *opaque, QemuOpts *opts,
>>> Error **errp)
>>> char *id = (char *)qemu_opts_id(opts);
>>> assert(id);
>>> - vnc_display_init(id);
>>> + vnc_display_init(id, &local_err);
>>> + if (local_err) {
>>> + error_reportf_err(local_err, "Failed to init VNC server: ");
>>> + exit(1);
>>> + }
>>> vnc_display_open(id, &local_err);
>>> if (local_err != NULL) {
>>> error_reportf_err(local_err, "Failed to start VNC server: ");
>> Conflicts with my "[PATCH 24/31] vl: Clean up error reporting in
>> vnc_init_func()". Your patch shows that mine is incomplete.
>>
>> Without my patch, there's no real reason for yours, however. The two
>> should be squashed together.
> Ah, I noticed your patch 24/31. OK, let's squash.
> Should I write a new patch by
> - updating to error_propagate(...) if vnc_display_init() fails
> &&
> - modifying [Issue2] ?
> Or you do this in your original patch?
If you send a v2 along that lines, I'll probably pick your patch into my
series. Should work even in case your series gets merged first.
> BTW, for your patch 24/31, the updated passed errp for vnc_init_func
> is &error_fatal,
> then the system will exit(1) when running error_propagate(...) which calls
> error_handle_fatal(...). This means the following two lines will not
> be touched.
> But if we want the following prepended error message, could we move it
> earlier than
> the error_propagare? I mean:
>
> if (local_err != NULL) {
> - error_reportf_err(local_err, "Failed to start VNC server: ");
> - exit(1);
> + error_prepend(&local_err, "Failed to start VNC server: ");
> + error_propagate(errp, local_err);
> + return -1;
> }
Both
error_propagate(errp, local_err);
error_prepend(errp, "Failed to start VNC server: ");
and
error_prepend(&local_err, "Failed to start VNC server: ");
error_propagate(errp, local_err);
work. The former is slightly more efficient when errp is null. But
you're right, it fails to include the "Failed to start VNC server: "
prefix with &error_fatal. Thus, the latter is preferrable.
