Re: [Qemu-devel] "make check -j4" hangs (was: Re: chardev/char-socket: add POLLHUP handler)

[Alistair Francis]

On Thu, Feb 8, 2018 at 1:12 PM, Peter Maydell  wrote:
> On 8 February 2018 at 19:13, Thomas Huth  wrote:
>> I'm currently facing some issues with "make check -j4" (i.e. running the
>> tests in parallel). Git bisect blames this commit - though I'm not sure
>> whether this is really the right one ... Starting with this commit, I
>> saw hangs in test-filter-redirector, but git master rather seems to hang
>> with vhost-user-test instead.
>> Stefan also had issues with "make check -j4" today, so it's apparently
>> not only me ... can somebody else reproduce the problem with the git
>> master branch?
>
> Yeah, I was seeing odd make check hangs with parallelization enabled
> too, on vhost-user-test... (my builds for merge tests are almost
> all non-parallelized I think).

I don't only see hangs I also am seeing this:

qemu-system-i386: -chardev
socket,id=chr-test,path=/tmp/vhost-test-wxuOIX/test.sock: Failed to
connect socket /tmp/vhost-test-wxuOIX/test.sock: No such file or
directory
socket_accept failed: Resource temporarily unavailable
**
ERROR:tests/libqtest.c:218:qtest_init_without_qmp_handshake: assertion
failed: (s->fd >= 0 && s->qmp_fd >= 0)
GTester: last random seed: R02Sa67ba85090274c01deb9c2d15b044c10

It isn't 100% reproducible though.

Alistair

>
> thanks
> -- PMM
>

Re: [Qemu-devel] "make check -j4" hangs (was: Re: chardev/char-socket: add POLLHUP handler)

[Peter Maydell]

On 8 February 2018 at 19:13, Thomas Huth  wrote:
> I'm currently facing some issues with "make check -j4" (i.e. running the
> tests in parallel). Git bisect blames this commit - though I'm not sure
> whether this is really the right one ... Starting with this commit, I
> saw hangs in test-filter-redirector, but git master rather seems to hang
> with vhost-user-test instead.
> Stefan also had issues with "make check -j4" today, so it's apparently
> not only me ... can somebody else reproduce the problem with the git
> master branch?

Yeah, I was seeing odd make check hangs with parallelization enabled
too, on vhost-user-test... (my builds for merge tests are almost
all non-parallelized I think).

thanks
-- PMM

[Qemu-devel] "make check -j4" hangs (was: Re: chardev/char-socket: add POLLHUP handler)

[Thomas Huth]

On 30.01.2018 20:49, Paolo Bonzini wrote:
> On 25/01/2018 08:51, Klim Kireev wrote:
>> The following behavior was observed for QEMU configured by libvirt
>> to use guest agent as usual for the guests without virtio-serial
>> driver (Windows or the guest remaining in BIOS stage).
>>
>> In QEMU on first connect to listen character device socket
>> the listen socket is removed from poll just after the accept().
>> virtio_serial_guest_ready() returns 0 and the descriptor
>> of the connected Unix socket is removed from poll and it will
>> not be present in poll() until the guest will initialize the driver
>> and change the state of the serial to "guest connected".
>>
>> In libvirt connect() to guest agent is performed on restart and
>> is run under VM state lock. Connect() is blocking and can
>> wait forever.
>> In this case libvirt can not perform ANY operation on that VM.
>>
>> The bug can be easily reproduced this way:
>>
>> Terminal 1:
>> qemu-system-x86_64 -m 512 -device pci-serial,chardev=serial1 -chardev 
>> socket,id=serial1,path=/tmp/console.sock,server,nowait
>> (virtio-serial and isa-serial also fit)
>>
>> Terminal 2:
>> minicom -D unix\#/tmp/console.sock
>> (type something and press enter)
>> C-a x (to exit)
>>
>> Do 3 times:
>> minicom -D unix\#/tmp/console.sock
>> C-a x
>>
>> It needs 4 connections, because the first one is accepted by QEMU, then two 
>> are queued by
>> the kernel, and the 4th blocks.
>>
>> The problem is that QEMU doesn't add a read watcher after succesful read
>> until the guest device wants to acquire recieved data, so
>> I propose to install a separate pullhup watcher regardless of
>> whether the device waits for data or not.
>>
>> Signed-off-by: Klim Kireev 
>> ---
>> Changelog:
>> v2: Remove timer as a redundant feature
>>
>> v3: Remove read call and return G_SOURCE_REMOVE
>>
>> v4: Move to GSource API
>>
>> v5: Fix git typos 
>>
>>  chardev/char-socket.c | 22 ++
>>  1 file changed, 22 insertions(+)
>>
>> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
>> index 77cdf487eb..a340af6cd3 100644
>> --- a/chardev/char-socket.c
>> +++ b/chardev/char-socket.c
>> @@ -42,6 +42,7 @@ typedef struct {
>>  QIOChannel *ioc; /* Client I/O channel */
>>  QIOChannelSocket *sioc; /* Client master channel */
>>  QIONetListener *listener;
>> +GSource *hup_source;
>>  QCryptoTLSCreds *tls_creds;
>>  int connected;
>>  int max_size;
>> @@ -352,6 +353,12 @@ static void tcp_chr_free_connection(Chardev *chr)
>>  s->read_msgfds_num = 0;
>>  }
>>  
>> +if (s->hup_source != NULL) {
>> +g_source_destroy(s->hup_source);
>> +g_source_unref(s->hup_source);
>> +s->hup_source = NULL;
>> +}
>> +
>>  tcp_set_msgfds(chr, NULL, 0);
>>  remove_fd_in_watch(chr);
>>  object_unref(OBJECT(s->sioc));
>> @@ -455,6 +462,15 @@ static gboolean tcp_chr_read(QIOChannel *chan, 
>> GIOCondition cond, void *opaque)
>>  return TRUE;
>>  }
>>  
>> +static gboolean tcp_chr_hup(QIOChannel *channel,
>> +   GIOCondition cond,
>> +   void *opaque)
>> +{
>> +Chardev *chr = CHARDEV(opaque);
>> +tcp_chr_disconnect(chr);
>> +return G_SOURCE_REMOVE;
>> +}
>> +
>>  static int tcp_chr_sync_read(Chardev *chr, const uint8_t *buf, int len)
>>  {
>>  SocketChardev *s = SOCKET_CHARDEV(chr);
>> @@ -528,6 +544,12 @@ static void tcp_chr_connect(void *opaque)
>> tcp_chr_read,
>> chr, chr->gcontext);
>>  }
>> +
>> +s->hup_source = qio_channel_create_watch(s->ioc, G_IO_HUP);
>> +g_source_set_callback(s->hup_source, (GSourceFunc)tcp_chr_hup,
>> +  chr, NULL);
>> +g_source_attach(s->hup_source, chr->gcontext);
>> +
>>  qemu_chr_be_event(chr, CHR_EVENT_OPENED);
>>  }
>>  
>>
> 
> Queued, thanks.

 Hi!

I'm currently facing some issues with "make check -j4" (i.e. running the
tests in parallel). Git bisect blames this commit - though I'm not sure
whether this is really the right one ... Starting with this commit, I
saw hangs in test-filter-redirector, but git master rather seems to hang
with vhost-user-test instead.
Stefan also had issues with "make check -j4" today, so it's apparently
not only me ... can somebody else reproduce the problem with the git
master branch?

 Thomas