[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [Bug 1686390] Re: vnc server closed socket after arrow "dow
[Qemu-devel] [Bug 1686390] Re: vnc server closed socket after arrow "down" keyevent
Thu, 27 Apr 2017 14:10:46 -0000
> Wrote wire 0x5579e6bd2c60 51480 -> -2
That is QIO_CHANNEL_ERR_BLOCK, aka EAGAIN.
This is fixed in the 2.9.0 release with
Author: Michael Tokarev <address@hidden>
Date: Fri Feb 3 12:52:29 2017 +0300
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):
msg_controllen=0, msg_flags=0}, 0) = 103950
msg_controllen=0, msg_flags=0}, 0) = -1 EAGAIN
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 <address@hidden>
Reviewed-by: Daniel P. Berrange <address@hidden>
Cc: Daniel P. Berrange <address@hidden>
Cc: Gerd Hoffmann <address@hidden>
Signed-off-by: Gerd Hoffmann <address@hidden>
** Changed in: qemu
Status: New => Fix Released
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
vnc server closed socket after arrow "down" keyevent
Status in QEMU:
This is a rewrite for https://bugs.launchpad.net/qemu/+bug/1670377
QEMU 2.6 or later
Once get into grub boot interface(choose boot os, or recovery mode),
keep holding press arrow down button for a while(no release), qemu
will close the connection, vnc used zrle mode.
1. when stopped at grub interface, only arrow up and down key could trigger
2. only in zrle or tight mode, could work well in raw mode
2. it only triggered by remote connection, not happen if local vncviewer and
A trace is attached.
To manage notifications about this bug go to: