| H A D | vnc.c | diff 537848ee62195fc06c328b1cd64f4218f404a7f1 Fri Feb 03 03:52:29 CST 2017 Michael Tokarev <mjt@tls.msk.ru> vnc: do not disconnect on EAGAIN
When qemu vnc server is trying to send large update to clients,
there might be a situation when system responds with something
like EAGAIN, indicating that there's no system memory to send
that much data (depending on the network speed, client and server
and what is happening). In this case, something like this happens
on qemu side (from strace):
sendmsg(16, {msg_name(0)=NULL,
msg_iov(1)=[{"\244\"..., 729186}],
msg_controllen=0, msg_flags=0}, 0) = 103950
sendmsg(16, {msg_name(0)=NULL,
msg_iov(1)=[{"lz\346"..., 1559618}],
msg_controllen=0, msg_flags=0}, 0) = -1 EAGAIN
sendmsg(-1, {msg_name(0)=NULL,
msg_iov(1)=[{"lz\346"..., 1559618}],
msg_controllen=0, msg_flags=0}, 0) = -1 EBADF
qemu closes the socket before the retry, and obviously it gets EBADF
when trying to send to -1.
This is because there WAS a special handling for EAGAIN, but now it doesn't
work anymore, after commit 04d2529da27db512dcbd5e99d0e26d333f16efcc, because
now in all error-like cases we initiate vnc disconnect.
This change were introduced in qemu 2.6, and caused numerous grief for many
people, resulting in their vnc clients reporting sporadic random disconnects
from vnc server.
Fix that by doing the disconnect only when necessary, i.e. omitting this
very case of EAGAIN.
Hopefully the existing condition (comparing with QIO_CHANNEL_ERR_BLOCK)
is sufficient, as the original code (before the above commit) were
checking for other errno values too.
Apparently there's another (semi?)bug exist somewhere here, since the
code tries to write to fd# -1, it probably should check if the connection
is open before. But this isn't important.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1486115549-9398-1-git-send-email-mjt@msgid.tls.msk.ru
Fixes: 04d2529da27db512dcbd5e99d0e26d333f16efcc
Cc: Daniel P. Berrange <berrange@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff 537848ee62195fc06c328b1cd64f4218f404a7f1 Fri Feb 03 03:52:29 CST 2017 Michael Tokarev <mjt@tls.msk.ru> vnc: do not disconnect on EAGAIN
When qemu vnc server is trying to send large update to clients,
there might be a situation when system responds with something
like EAGAIN, indicating that there's no system memory to send
that much data (depending on the network speed, client and server
and what is happening). In this case, something like this happens
on qemu side (from strace):
sendmsg(16, {msg_name(0)=NULL,
msg_iov(1)=[{"\244\"..., 729186}],
msg_controllen=0, msg_flags=0}, 0) = 103950
sendmsg(16, {msg_name(0)=NULL,
msg_iov(1)=[{"lz\346"..., 1559618}],
msg_controllen=0, msg_flags=0}, 0) = -1 EAGAIN
sendmsg(-1, {msg_name(0)=NULL,
msg_iov(1)=[{"lz\346"..., 1559618}],
msg_controllen=0, msg_flags=0}, 0) = -1 EBADF
qemu closes the socket before the retry, and obviously it gets EBADF
when trying to send to -1.
This is because there WAS a special handling for EAGAIN, but now it doesn't
work anymore, after commit 04d2529da27db512dcbd5e99d0e26d333f16efcc, because
now in all error-like cases we initiate vnc disconnect.
This change were introduced in qemu 2.6, and caused numerous grief for many
people, resulting in their vnc clients reporting sporadic random disconnects
from vnc server.
Fix that by doing the disconnect only when necessary, i.e. omitting this
very case of EAGAIN.
Hopefully the existing condition (comparing with QIO_CHANNEL_ERR_BLOCK)
is sufficient, as the original code (before the above commit) were
checking for other errno values too.
Apparently there's another (semi?)bug exist somewhere here, since the
code tries to write to fd# -1, it probably should check if the connection
is open before. But this isn't important.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1486115549-9398-1-git-send-email-mjt@msgid.tls.msk.ru
Fixes: 04d2529da27db512dcbd5e99d0e26d333f16efcc
Cc: Daniel P. Berrange <berrange@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff 624cdd46d7f67fa2d23e87ffe0a36a569edde11a Tue Aug 02 05:45:24 CDT 2016 Daniel P. Berrange <berrange@redhat.com> vnc: don't crash getting server info if lsock is NULL
When VNC is started with '-vnc none' there will be no
listener socket present. When we try to populate the
VncServerInfo we'll crash accessing a NULL 'lsock'
field.
#0 qio_channel_socket_get_local_address (ioc=0x0, errp=errp@entry=0x7ffd5b8aa0f0) at io/channel-socket.c:33
#1 0x00007f4b9a297d6f in vnc_init_basic_info_from_server_addr (errp=0x7ffd5b8aa0f0, info=0x7f4b9d425460, ioc=<optimized out>) at ui/vnc.c:146
#2 vnc_server_info_get (vd=0x7f4b9e858000) at ui/vnc.c:223
#3 0x00007f4b9a29d318 in vnc_qmp_event (vs=0x7f4b9ef82000, vs=0x7f4b9ef82000, event=QAPI_EVENT_VNC_CONNECTED) at ui/vnc.c:279
#4 vnc_connect (vd=vd@entry=0x7f4b9e858000, sioc=sioc@entry=0x7f4b9e8b3a20, skipauth=skipauth@entry=true, websocket=websocket @entry=false) at ui/vnc.c:2994
#5 0x00007f4b9a29e8c8 in vnc_display_add_client (id=<optimized out>, csock=<optimized out>, skipauth=<optimized out>) at ui/v nc.c:3825
#6 0x00007f4b9a18d8a1 in qmp_marshal_add_client (args=<optimized out>, ret=<optimized out>, errp=0x7ffd5b8aa230) at qmp-marsh al.c:123
#7 0x00007f4b9a0b53f5 in handle_qmp_command (parser=<optimized out>, tokens=<optimized out>) at /usr/src/debug/qemu-2.6.0/mon itor.c:3922
#8 0x00007f4b9a348580 in json_message_process_token (lexer=0x7f4b9c78dfe8, input=0x7f4b9c7350e0, type=JSON_RCURLY, x=111, y=5 9) at qobject/json-streamer.c:94
#9 0x00007f4b9a35cfeb in json_lexer_feed_char (lexer=lexer@entry=0x7f4b9c78dfe8, ch=125 '}', flush=flush@entry=false) at qobj ect/json-lexer.c:310
#10 0x00007f4b9a35d0ae in json_lexer_feed (lexer=0x7f4b9c78dfe8, buffer=<optimized out>, size=<optimized out>) at qobject/json -lexer.c:360
#11 0x00007f4b9a348679 in json_message_parser_feed (parser=<optimized out>, buffer=<optimized out>, size=<optimized out>) at q object/json-streamer.c:114
#12 0x00007f4b9a0b3a1b in monitor_qmp_read (opaque=<optimized out>, buf=<optimized out>, size=<optimized out>) at /usr/src/deb ug/qemu-2.6.0/monitor.c:3938
#13 0x00007f4b9a186751 in tcp_chr_read (chan=<optimized out>, cond=<optimized out>, opaque=0x7f4b9c7add40) at qemu-char.c:2895
#14 0x00007f4b92b5c79a in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#15 0x00007f4b9a2bb0c0 in glib_pollfds_poll () at main-loop.c:213
#16 os_host_main_loop_wait (timeout=<optimized out>) at main-loop.c:258
#17 main_loop_wait (nonblocking=<optimized out>) at main-loop.c:506
#18 0x00007f4b9a0835cf in main_loop () at vl.c:1934
#19 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:4667
Do an upfront check for a NULL lsock and report an error to
the caller, which matches behaviour from before
commit 04d2529da27db512dcbd5e99d0e26d333f16efcc
Author: Daniel P. Berrange <berrange@redhat.com>
Date: Fri Feb 27 16:20:57 2015 +0000
ui: convert VNC server to use QIOChannelSocket
where getsockname() would be given a FD value -1 and thus report
an error to the caller.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1470134726-15697-2-git-send-email-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff 83cf07b0b577bde1afe1329d25bbcc762966e637 Wed Jun 08 05:42:56 CDT 2016 Daniel P. Berrange <berrange@redhat.com> ui: fix regression in printing VNC host/port on startup
If VNC is chosen as the compile time default display backend,
QEMU will print the host/port it listens on at startup.
Previously this would look like
VNC server running on '::1:5900'
but in 04d2529da27db512dcbd5e99d0e26d333f16efcc the ':' was
accidentally replaced with a ';'. This the ':' back.
Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1465382576-25552-1-git-send-email-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff 04d2529da27db512dcbd5e99d0e26d333f16efcc Fri Feb 27 10:20:57 CST 2015 Daniel P. Berrange <berrange@redhat.com> ui: convert VNC server to use QIOChannelSocket
The minimal first step conversion to use QIOChannelSocket
classes instead of directly using POSIX sockets API. This
will later be extended to also cover the TLS, SASL and
websockets code.
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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