This reverts commit 15124e1420. It breaks
debuggability of qemu and is no longer needed as the problem has
now been addressed in a different way.
Instead we provide a comment about why these signals must be
handled asynchronously.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
[PMM: added comment]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Add the termination signals SIGINT, SIGHUP and SIGTERM to the
list of signals which we handle synchronously via a signalfd.
This avoids a race condition where if we took the SIGTERM
in the middle of qemu_shutdown_requested:
int r = shutdown_requested;
[SIGTERM here...]
shutdown_requested = 0;
then the setting of the shutdown_requested flag by
termsig_handler() would be lost and QEMU would fail to
shut down. This was causing 'make check' to hang occasionally.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1411660269-11081-1-git-send-email-peter.maydell@linaro.org
Cc: qemu-stable@nongnu.org
On a system with a low limit of open files the initialization
of the event notifier could fail and QEMU exits without printing any
error information to the user.
The problem can be easily reproduced by enforcing a low limit of open
files and start QEMU with enough I/O threads to hit this limit.
The same problem raises, without the creation of I/O threads, while
QEMU initializes the main event loop by enforcing an even lower limit of
open files.
This commit adds an error message on failure:
# qemu [...] -object iothread,id=iothread0 -object iothread,id=iothread1
qemu: Failed to initialize event notifier: Too many open files in system
Signed-off-by: Chrysostomos Nanakos <cnanakos@grnet.gr>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The main AioContext should be accessed explicitly via qemu_get_aio_context().
Most of the time, using it is not the right thing to do.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When running under qtest we don't actually have any vcpu threads
to be starved, so the warning about the I/O thread spinning isn't
relevant, and the way qtest manipulates the simulated clock means
the warning is produced a lot as a false positive. Suppress it if
qtest_enabled(), so 'make check' output is less noisy.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
If slirp needs to emulate tcp timeout, then the timeout value
for mainloop should be more precise, which is determined by
slirp's fasttimo or slowtimo. Achieve this by swap the logic
sequence of slirp_pollfds_fill and slirp_update_timeout.
Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Rearrange timer.h so it is in order by function type.
Make legacy functions call non-legacy functions rather than vice-versa.
Convert cpus.c to use new API.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Remove alarm timers from qemu-timers.c now we use g_poll / ppoll
instead.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Convert mainloop to use timeout from default timerlist group
(i.e. the current 3 static timers)
main-loop.c produces a (possibly spurious) warning about
multiple iterations. Adapt the way this works for a signed
timeout and make the warning a bit safer.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The .io_flush() handler no longer exists and has no users. Drop the
io_flush argument to aio_set_fd_handler() and related functions.
The AioFlushEventNotifierHandler and AioFlushHandler typedefs are no
longer used and are dropped too.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The header slirp/slirp.h is an internal header for slirp, and
main-loop.c does not use internals from there. Instead, it uses
public functions (slirp_update_timeout(), slirp_pollfds_fill()
etc) which are declared in slirp/libslirp.h.
Including slirp/slirp.h is somewhat dangerous since it redefines
errno on WIN32, so any file including it may misbehave wrt errno.
Unfortunately libslirp isn't self-contained, it needs declaration
of struct in_addr, which is provided by qemu/sockets.h. Maybe
instead of #including qemu/sockets.h before libslirp.h, it is
better to make the latter self-contained.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
pollfds_fill() and pollfds_poll() translate GPollFD to rfds/wfds/xfds
for sockets on win32. select(2) is the underlying system call which is
used to monitor sockets for activity.
Currently file descriptors that monitor G_IO_ERR will be included in
both rfds and wfds. As a result, select(2) will report writability on
file descriptors where we only really wanted to monitor readability
(with errors).
slirp_pollfds_poll() hit this issue: UDP sockets are blocking sockets so
we hang in sorecvfrom() when G_IO_ERR is set due to the socket being
writable (we only wanted to check for readability).
This patch fixes the slirp_pollfds_poll() hang.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1368718561-7816-2-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The char-flow refactoring introduced a busy-wait that depended on
an action from the VCPU thread. However, the VCPU thread could
never take that action because the busy-wait starved the VCPU thread
of the BQL because it never dropped the mutex while running select.
Paolo doesn't want to drop this optimization for fear that we will
stop detecting these busy waits. I'm afraid to keep this optimization
even with the busy-wait fixed because I think a similar problem can
occur just with heavy I/O thread load manifesting itself as VCPU pauses.
As a compromise, introduce an artificial timeout after a thousand
iterations but print a rate limited warning when this happens. This
let's us still detect when this condition occurs without it being
a fatal error.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Message-id: 1365169560-11012-1-git-send-email-aliguori@us.ibm.com
It is very useful to get the main loop AioContext, which is a static
variable in main-loop.c.
I'm not sure whether qemu_get_aio_context() will be necessary in the
future once devices focus on using their own AioContext instead of the
main loop AioContext, but for now it allows us to refactor code to
support multiple AioContext while actually passing the main loop
AioContext.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Slirp uses rfds/wfds/xfds more extensively than other QEMU components.
The rarely-used out-of-band TCP data feature is used. That means we
need the full table of select(2) to g_poll(3) events:
rfds -> G_IO_IN | G_IO_HUP | G_IO_ERR
wfds -> G_IO_OUT | G_IO_ERR
xfds -> G_IO_PRI
I came up with this table by looking at Linux fs/select.c which maps
select(2) to poll(2) internally.
Another detail to watch out for are the global variables that reference
rfds/wfds/xfds during slirp_select_poll(). sofcantrcvmore() and
sofcantsendmore() use these globals to clear fd_set bits. When
sofcantrcvmore() is called, the wfds bit is cleared so that the write
handler will no longer be run for this iteration of the event loop.
This actually seems buggy to me since TCP connections can be half-closed
and we'd still want to handle data in half-duplex fashion. I think the
real intention is to avoid running the read/write handler when the
socket has been fully closed. This is indicated with the SS_NOFDREF
state bit so we now check for it before invoking the TCP write handler.
Note that UDP/ICMP code paths don't care because they are
connectionless.
Note that slirp/ has a lot of tabs and sometimes mixed tabs with spaces.
I followed the style of the surrounding code.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 1361356113-11049-6-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Use g_poll(3) instead of select(2). Well, this is kind of a cheat.
It's true that we're now using g_poll(3) on POSIX hosts but the *_fill()
and *_poll() functions are still using rfds/wfds/xfds.
We've set the scene to start converting *_fill() and *_poll() functions
step-by-step until no more rfds/wfds/xfds users remain. Then we'll drop
the temporary gpollfds_from_select() and gpollfds_to_select() functions
and be left with native g_poll(2).
On Windows things are a little crazy: convert from rfds/wfds/xfds to
GPollFDs, back to rfds/wfds/xfds, call select(2), rfds/wfds/xfds back to
GPollFDs, and finally back to rfds/wfds/xfds again. This is only
temporary and keeps the Windows build working through the following
patches. We'll drop this excessive conversion later and be left with a
single GPollFDs -> select(2) -> GPollFDs sequence that allows Windows to
use select(2) while the rest of QEMU only knows about GPollFD.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 1361356113-11049-3-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The current implementation of os_host_main_loop_wait() on Windows,
returns 1 only when a g_poll() event occurs because the return value of
select() is overridden. This is wrong as we may skip a socket event, as
shown in this example:
1. select() returns 0
2. g_poll() returns 1 (socket event occurs)
3. os_host_main_loop_wait() returns 1
4. qemu_iohandler_poll() sees no socket event because select() has
return before the event occurs
5. select() returns 1
6. g_poll() returns 0 (g_poll overrides select's return value)
7. os_host_main_loop_wait() returns 0
8. qemu_iohandler_poll() doesn't check for socket events because the
return value of os_host_main_loop_wait() is zero.
9. goto 5
This patch use one variable for each of these return values, so we don't
miss a select() event anymore.
Also move the call to select() after g_poll(), this will improve latency
as we don't have to go through two os_host_main_loop_wait() calls to
detect a socket event.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
