Whenever serial_xmit fails to transmit a byte it adds a watch that would
call it again when the "line" becomes ready. This results in a retry
chain:
serial_xmit -> add_watch -> serial_xmit
Each chain is able to transmit one character, and for every character
passed to serial by the guest driver a new chain is spawned.
The problem lays with the fact that a new chain is spawned even when
there is one already waiting on the watch. So there can be several retry
chains waiting concurrently on one "line". Every chain tries to transmit
current character, so character order is not messed up. But also every
chain increases retry counter (tsr_retry). If there are enough
concurrent chains this counter will hit MAX_XMIT_RETRY value and
the character will be dropped.
To reproduce this bug you need to feed serial output to some program
consuming it slowly enough. A python script from bug #1335444
description is an example of such program.
This commit changes retry logic in the following way to avoid
concurrency: instead of spawning a new chain for each character being
transmitted spawn only one and make it transmit characters until FIFO is
empty.
The change consists of two parts:
- add a do {} while () loop in serial_xmit (diff is a bit erratic
for this part, diff -w will show actual change),
- do not call serial_xmit from serial_ioport_write if there is one
waiting on the watch already.
This should fix another issue causing bug #1335444.
Signed-off-by: Kirill Batuzov <batuzovk@ispras.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
On FreeBSD polling a master pty while the other end is not connected
with G_IO_OUT only results in an endless wait. This is different from
the Linux behaviour, that returns immediately. In order to demonstrate
this, I have the following example code:
http://xenbits.xen.org/people/royger/test_poll.c
When executed on Linux:
$ ./test_poll
In callback
On FreeBSD instead, the callback never gets called:
$ ./test_poll
So, in order to workaround this, poll the source with G_IO_HUP (which
makes the code behave the same way on both Linux and FreeBSD).
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: Michael Tokarev <mjt@tls.msk.ru>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: xen-devel@lists.xenproject.org
[Add hw/char/cadence_uart.c too. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After previous Peter patch, they are redundant. This way we don't
assign them except when needed. Once there, there were lots of case
where the ".fields" indentation was wrong:
.fields = (VMStateField []) {
and
.fields = (VMStateField []) {
Change all the combinations to:
.fields = (VMStateField[]){
The biggest problem (appart from aesthetics) was that checkpatch complained
when we copy&pasted the code from one place to another.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Acked-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
The commit 88c1ee73d3
char/serial: Fix emptyness check
Still causes extra NULL byte(s) to be sent.
So if the fifo is empty, do not send an extra NULL byte.
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Don Slutz <dslutz@verizon.com>
Message-id: 1395160174-16006-1-git-send-email-dslutz@verizon.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This was guarding against a full fifo rather than an empty fifo when
popping. Fix.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
# By Alex Bligh (32) and others
# Via Stefan Hajnoczi
* stefanha/block: (42 commits)
win32-aio: drop win32_aio_flush_cb()
aio-win32: replace incorrect AioHandler->opaque usage with ->e
aio / timers: remove dummy_io_handler_flush from tests/test-aio.c
aio / timers: Remove legacy interface
aio / timers: Switch entire codebase to the new timer API
aio / timers: Add scripts/switch-timer-api
aio / timers: Add test harness for AioContext timers
aio / timers: convert block_job_sleep_ns and co_sleep_ns to new API
aio / timers: Convert rtc_clock to be a QEMUClockType
aio / timers: Remove main_loop_timerlist
aio / timers: Rearrange timer.h & make legacy functions call non-legacy
aio / timers: Add qemu_clock_get_ms and qemu_clock_get_ms
aio / timers: Remove legacy qemu_clock_deadline & qemu_timerlist_deadline
aio / timers: Remove alarm timers
aio / timers: Add documentation and new format calls
aio / timers: Use all timerlists in icount warp calculations
aio / timers: Introduce new API timer_new and friends
aio / timers: On timer modification, qemu_notify or aio_notify
aio / timers: Convert mainloop to use timeout
aio / timers: Convert aio_poll to use AioContext timers' deadline
...
Message-id: 1377202298-22896-1-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <anthony@codemonkey.ws>
This is an autogenerated patch using scripts/switch-timer-api.
Switch the entire code base to using the new timer API.
Note this patch may introduce some line length issues.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Convert stderr messages calling error_get_pretty()
to error_report().
Timestamp is prepended by -msg timstamp option with it.
Per Markus's comment below, A conversion from fprintf() to
error_report() is always an improvement, regardless of
error_get_pretty().
http://marc.info/?l=qemu-devel&m=137513283408601&w=2
But, it is not reasonable to convert them at one time
because fprintf() is used everwhere in qemu.
So, it should be done step by step with avoiding regression.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Copy&paste error in serial.c causes a crash when attempting
to read from UART (if there is no data to be read)
Signed-off-by: Vladimir Senkov <hangup@gmail.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
* 'realize-isa.v2' of git://github.com/afaerber/qemu-cpu:
qdev: Drop FROM_QBUS() macro
isa: QOM'ify ISADevice
isa: QOM'ify ISABus
i8259: Convert PICCommonState to use QOM realizefn
kvm/i8259: QOM'ify some more
i8259: QOM'ify some more
i8254: Convert PITCommonState to QOM realizefn
kvm/i8254: QOM'ify some more
i8254: QOM'ify some more
isa: Use realizefn for ISADevice
cs4231a: QOM'ify some more
gus: QOM'ify some more
These three lines are common to both FIFO and regular mode. Just factor
them out to outside the if rather than replicate the same lines inside
both if and else.
Cc: qemu-trivial@nongnu.org
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Use the generic Fifo8 helper provided by QEMU, rather than re-implement
privately.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Some cosmetic fixes to char/serial fixing some checkpatch errors.
Cc: qemu-trivial@nongnu.org
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Drop ISADeviceClass::init and the resulting no-op initfn and let
children implement their own realizefn. Adapt error handling.
Split off an instance_init where sensible.
Signed-off-by: Andreas Färber <afaerber@suse.de>
