Commit graph android_kernel_sony_sdm845/drivers/char/virtio_console.c
Message SHA1
virtio: console: tell host of open ports after resume from s3/s4
If a port was open before going into one of the sleep states, the port
can continue normal operation after restore.  However, the host has to
be told that the guest side of the connection is open to restore
pre-suspend state.

This wasn't noticed so far due to a bug in qemu that was fixed recently
(which marked the guest-side connection as always open).

CC: stable@vger.kernel.org   # Only for 3.3

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Amit Shah   authored and   Michael S. Tsirkin   commited 2012-05-17 12:14:33 +03:00
fa8b66ccd2
simple_open: automatically convert to simple_open()
Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op.  This leads to a
proliferation of the default_open() implementation across the entire
tree.

Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().

This replacement was done with the following semantic patch:

<smpl>
@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i->i_private)
-f->private_data = i->i_private;
|
-f->private_data = i->i_private;
)
-return 0;
-}

@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};
</smpl>

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Stephen Boyd   authored and   Linus Torvalds   commited 2012-04-05 15:25:50 -07:00
234e340582
virtio: console: Disable callbacks for virtqueues at start of S4 freeze
To ensure we don't receive any more interrupts from the host after we
enter the freeze function, disable all vq interrupts.

There wasn't any problem seen due to this in tests, but applying this
patch makes the freeze case more robust.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2012-01-12 15:44:45 +10:30
c743d09dbd
virtio: console: Add freeze and restore handlers to support S4
Remove all vqs and associated buffers in the freeze callback which
prepares us to go into hibernation state.  On restore, re-create all the
vqs and populate the input vqs with buffers to get to the pre-hibernate
state.

Note: Any outstanding unconsumed buffers are discarded; which means
there's a possibility of data loss in case the host or the guest didn't
consume any data already present in the vqs.  This can be addressed in a
later patch series, perhaps in virtio common code.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2012-01-12 15:44:45 +10:30
2b8f41d846
virtio: console: Move vq and vq buf removal into separate functions
This common code will be shared with the PM freeze function.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2012-01-12 15:44:45 +10:30
a0e2dbfc22
virtio: rename virtqueue_add_buf_gfp to virtqueue_add_buf
Remove wrapper functions. This makes the allocation type explicit in
all callers; I used GPF_KERNEL where it seemed obvious, left it at
GFP_ATOMIC otherwise.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Rusty Russell   commited 2012-01-12 15:44:42 +10:30
f96fde41f7
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
  Revert "tracing: Include module.h in define_trace.h"
  irq: don't put module.h into irq.h for tracking irqgen modules.
  bluetooth: macroize two small inlines to avoid module.h
  ip_vs.h: fix implicit use of module_get/module_put from module.h
  nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
  include: replace linux/module.h with "struct module" wherever possible
  include: convert various register fcns to macros to avoid include chaining
  crypto.h: remove unused crypto_tfm_alg_modname() inline
  uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
  pm_runtime.h: explicitly requires notifier.h
  linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
  miscdevice.h: fix up implicit use of lists and types
  stop_machine.h: fix implicit use of smp.h for smp_processor_id
  of: fix implicit use of errno.h in include/linux/of.h
  of_platform.h: delete needless include <linux/module.h>
  acpi: remove module.h include from platform/aclinux.h
  miscdevice.h: delete unnecessary inclusion of module.h
  device_cgroup.h: delete needless include <linux/module.h>
  net: sch_generic remove redundant use of <linux/module.h>
  net: inet_timewait_sock doesnt need <linux/module.h>
  ...

Fix up trivial conflicts (other header files, and  removal of the ab3550 mfd driver) in
 - drivers/media/dvb/frontends/dibx000_common.c
 - drivers/media/video/{mt9m111.c,ov6650.c}
 - drivers/mfd/ab3550-core.c
 - include/linux/dmaengine.h

Linus Torvalds   commited 2011-11-06 19:44:47 -08:00
32aaeffbd4
virtio: console: wait for first console port for early console output
On s390 I have seen some random

"Warning: unable to open an initial console"

boot failure. Turns out that tty_open fails, because the
hvc_alloc was not yet done. In former times this could not happen,
since the probe function automatically called hvc_alloc. With newer
versions (multiport) some host<->guest interaction is required
before hvc_alloc is called. This might be too late, especially if
an initramfs is involved. Lets use a completion if we have
multiport and an early console.

[Amit:
  * Use NULL instead of 0 for pointer comparison
  * Rename 'port_added' to 'early_console_added'
  * Re-format, re-word commit message
  * Rebase patch on top of current queue]

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Acked-by: Chrstian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Christian Borntraeger   authored and   Rusty Russell   commited 2011-11-02 11:41:01 +10:30
5e38483b35
virtio: console: add port stats for bytes received, sent and discarded
This commit adds port-specific stats for the number of bytes received,
sent and discarded.  They're exposed via the debugfs interface.  This
data can be used to check for data loss bugs (or disprove such claims).
It can also be used for accounting, if there's such a need.

The stats remain valid throughout the lifetime of the port.  Unplugging
a port will reset the stats.  The numbers are not reset across port
opens/closes.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:41:01 +10:30
17e5b4f20a
virtio: console: make discard_port_data() use get_inbuf()
discard_port_data() used virtqueue_get_buf() directly instead of using
get_inbuf().  Fix this, so that we get accounting for all received
bytes.  This also simplifies the code a lot.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:41:00 +10:30
2d24cdaa6e
virtio: console: rename variable
'ret' is a misnomer in discard_port_data() since we don't return the
value.  Rename it to 'err'.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:41:00 +10:30
ce072a0cee
virtio: console: make get_inbuf() return port->inbuf if present
Instead of pulling in a buffer from the vq each time it's called,
get_inbuf() now checks if the current active buffer, in port->inbuf is
valid.  If it is, just returns a pointer to it.  This ends up
simplifying a lot of code calling get_inbuf() since the check for
port->inbuf being valid was done by all the callers.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:41:00 +10:30
d25a9ddae9
virtio: console: Fix return type for get_inbuf()
get_inbuf() returns void *.  There's no reason to return void pointers
instead of the correct struct port_buffer *.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:41:00 +10:30
defde66996
virtio: console: Use wait_event_freezable instead of _interruptible
Get ready to support suspend/resume by using the freezable calls so that
blocking read/write syscalls are handled properly across suspend/resume.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:41:00 +10:30
a08fa92d16
virtio: console: Ignore port name update request if name already set
We don't allow port name changes dynamically for a port.  So any
requests by the host to change the name are ignored.

Before this patch, if the hypervisor sent a port name while we had one
set already, we would leak memory equivalent to the size of the old
name.

This scenario wasn't expected so far, but with the suspend-resume
support, we'll send the VIRTIO_CONSOLE_PORT_READY message after restore,
which can get us into this situation.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:40:59 +10:30
291024ef35
virtio: console: Fix indentation
Convert spaces to tabs and fix indentation for an if statement split
into multiple lines.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-11-02 11:40:59 +10:30
286f9a226f
virtio-console: Use virtio_config_val() for retrieving config
This patch modifies virtio-console to use virtio_config_val() instead
of a 'if(virtio_has_feature()) vdev->config->get()' construct to retrieve
optional values from the config space.

Cc: Amit Shah <amit.shah@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Sasha Levin   authored and   Rusty Russell   commited 2011-11-02 11:40:58 +10:30
51c6d61ac5
drivers/char: Add module.h to those who were using it implicitly
A pending cleanup will mean that module.h won't be implicitly
everywhere anymore.  Make sure the modular drivers in char are
actually calling out for <module.h> explicitly in advance.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Paul Gortmaker   commited 2011-10-31 19:31:40 -04:00
c22405c98d
virtio console: don't manually set or finalize VIRTIO_CONSOLE_F_MULTIPORT.
That's already been done by the virtio infrastructure before the probe
function is called.

Reported-by: alexey.kardashevskiy@au1.ibm.com
Acked-by: Amit Shah <amit.shah@redhat.com>
Tested-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Rusty Russell   commited 2011-05-30 11:14:13 +09:30
177dbd9563
virtio: console: Enable call to hvc_remove() on console port remove
This call was disabled as hot-unplugging one virtconsole port led to
another virtconsole port freezing.

Upon testing it again, this now works, so enable it.

In addition, a bug was found in qemu wherein removing a port of one type
caused the guest output from another port to stop working.  I doubt it
was just this bug that caused it (since disabling the hvc_remove() call
did allow other ports to continue working), but since it's all solved
now, we're fine with hot-unplugging of virtconsole ports.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2011-04-21 22:57:00 +09:30
afa2689e19
virtio: console: Don't access vqs if device was unplugged
If a virtio-console device gets unplugged while a port is open, a
subsequent close() call on the port accesses vqs to free up buffers.
This can lead to a crash.

The buffers are already freed up as a result of the call to
unplug_ports() from virtcons_remove().  The fix is to simply not access
vq information if port->portdev is NULL.

Reported-by: juzhang <juzhang@redhat.com>
CC: stable@kernel.org
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Amit Shah   authored and   Linus Torvalds   commited 2011-03-06 10:44:13 -08:00
d7a62cd033
Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6
* 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
  serial: bfin_5xx: split uart RX lock from uart port lock to avoid deadlock
  68360serial: Plumb in rs_360_get_icount()
  n_gsm: copy mtu over when configuring via ioctl interface
  virtio: console: Move file back to drivers/char/

Linus Torvalds   commited 2011-02-10 12:19:58 -08:00
ce86d35d2f
virtio: console: Move file back to drivers/char/
Commit 728674a7e4 moved virtio_console.c
to drivers/tty/hvc/ under the perception of this being an hvc driver.
It was such once, but these days it has generic communication
capabilities as well, so move it to drivers/char/.

In the future, the hvc part from this file can be split off and moved
under drivers/tty/hvc/.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Amit Shah   authored and   Greg Kroah-Hartman   commited 2011-02-03 14:43:12 -08:00
51df0acc3d
tty: move hvc drivers to drivers/tty/hvc/
As requested by Arnd Bergmann, the hvc drivers are now
moved to the drivers/tty/hvc/ directory.  The virtio_console.c driver
was also moved, as it required the hvc_console.h file to be able to be
built, and it really is a hvc driver.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Greg Kroah-Hartman   commited 2011-01-13 12:03:00 -08:00
728674a7e4
Char: virtio_console, fix memory leak
Stanse found that in init_vqs, memory is leaked under certain
circumstanses (the fail path order is incorrect). Fix that by checking
allocations in one turn and free all of them at once if some fails
(some may be NULL, but this is OK).

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Amit Shah <amit.shah@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Jiri Slaby   authored and   Rusty Russell   commited 2010-11-24 15:21:12 +10:30
22e132ff26
virtio: console: Disable lseek(2) for port file operations
The ports are char devices; do not have seeking capabilities.  Calling
nonseekable_open() from the fops_open() call and setting the llseek fops
pointer to no_llseek ensures an lseek() call from userspace returns
-ESPIPE.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:04 +10:30
299fb61c08
virtio: console: Send SIGIO in case of port unplug
If a port has registered for SIGIO signals, let the application
know that the port is getting unplugged.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:04 +10:30
a461e11e7b
virtio: console: Send SIGIO on new data arrival on ports
Send a SIGIO signal when new data arrives on a port. This is sent only
when the process has requested for the signal to be sent using fcntl().

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:04 +10:30
55f6bcce36
virtio: console: Send SIGIO to processes that request it for host events
A process can request for SIGIO on host connect / disconnect events
using the O_ASYNC file flag using fcntl().

If that's requested, and if the guest-side connection for the port is
open, any host-side open/close events for that port will raise a SIGIO.
The process can then use poll() within the signal handler to find out
which port triggered the signal.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:03 +10:30
3eae0adea9
virtio: console: Reference counting portdev structs is not needed
Explain in a comment why there's no need to reference-count the portdev
struct: when a device is yanked out, we can't do anything more with it
anyway so just give up doing anything more with the data or the vqs and
exit cleanly.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:03 +10:30
e062013c7d
virtio: console: Add reference counting for port struct
When a port got hot-unplugged, when a port was open, any file operation
after the unplugging resulted in a crash. This is fixed by ref-counting
the port structure, and releasing it only when the file is closed.

This splits the unplug operation in two parts: first marks the port
as unavailable, removes all the buffers in the vqs and removes the port
from the per-device list of ports. The second stage, invoked when all
references drop to zero, releases the chardev and frees all other memory.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:03 +10:30
b353a6b821
virtio: console: Use cdev_alloc() instead of cdev_init()
This moves to using cdev on the heap instead of it being embedded in the
ports struct. This helps individual refcounting and will allow us to
properly remove cdev structs after hot-unplugs and close operations.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:03 +10:30
d22a69892b
virtio: console: Add a find_port_by_devt() function
To convert to using cdev as a pointer to avoid kref troubles, we have to
use a different method to get to a port from an inode than the current
container_of method.

Add find_port_by_devt() that looks up all portdevs and ports with those
portdevs to find the right port.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:03 +10:30
04950cdf07
virtio: console: Add a list of portdevs that are active
The virtio_console.c driver is capable of handling multiple devices at a
time. Maintain a list of devices for future traversal.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:02 +10:30
6bdf2afd02
virtio: console: open: Use a common path for error handling
Just re-arrange code for future patches.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:02 +10:30
8ad37e83c8
virtio: console: remove_port() should return void
When a port is removed, we have to assume the port is gone. So a
success/failure return value doesn't make sense.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:02 +10:30
7a2853178d
virtio: console: Make write() return -ENODEV on hot-unplug
When a port is hot-unplugged while an app was blocked on a write() call,
the call was unblocked but would not get an error returned.

Return -ENODEV to ensure the app knows the port has gone away.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:01 +10:30
f402811971
virtio: console: Make read() return -ENODEV on hot-unplug
When a port is hot-unplugged while an app was blocked on a read() call,
the call was unblocked but would not get an error returned.

Return -ENODEV to ensure the app knows the port has gone away.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:01 +10:30
b3dddb9e6d
virtio: console: Unblock poll on port hot-unplug
When a port is hot-unplugged while an app is blocked on poll(), unblock
the poll() and return.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:01 +10:30
8529a50427
virtio: console: Un-block reads on chardev close
If a chardev is closed, any blocked read / poll calls should just return
and not attempt to use other state.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:01 +10:30
3709ea7ae7
virtio: console: Check if portdev is valid in send_control_msg()
A portdev may have been hot-unplugged while a port was open()ed.  Skip
sending control messages when the portdev isn't valid.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:44:00 +10:30
84ec06c59a
virtio: console: Remove control vq data only if using multiport support
If a portdev isn't using multiport support, it won't have any control vq
data to remove.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:43:59 +10:30
96eb872b2a
virtio: console: Reset vdev before removing device
The virtqueues should be disabled before attempting to remove the
device.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-10-21 17:43:58 +10:30
0223895994
virtio: console: Don't block entire guest if host doesn't read data
If the host is slow in reading data or doesn't read data at all,
blocking write calls not only blocked the program that called write()
but the entire guest itself.

To overcome this, let's not block till the host signals it has given
back the virtio ring element we passed it.  Instead, send the buffer to
the host and return to userspace.  This operation then becomes similar
to how non-blocking writes work, so let's use the existing code for this
path as well.

This code change also ensures blocking write calls do get blocked if
there's not enough room in the virtio ring as well as they don't return
-EAGAIN to userspace.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
CC: stable@kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Amit Shah   authored and   Linus Torvalds   commited 2010-10-20 13:18:04 -07:00
531295e63b
virtio: console: Prevent userspace from submitting NULL buffers
A userspace could submit a buffer with 0 length to be written to the
host.  Prevent such a situation.

This was not needed previously, but recent changes in the way write()
works exposed this condition to trigger a virtqueue event to the host,
causing a NULL buffer to be sent across.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
CC: stable@kernel.org

Amit Shah   authored and   Rusty Russell   commited 2010-09-21 10:54:01 +09:30
65745422a8
virtio: console: Fix poll blocking even though there is data to read
I found this while working on a Linux agent for spice, the symptom I was
seeing was select blocking on the spice vdagent virtio serial port even
though there were messages queued up there.

virtio_console's port_fops_poll checks port->inbuf != NULL to determine
if read won't block. However if an application reads enough bytes from
inbuf through port_fops_read, to empty the current port->inbuf,
port->inbuf will be NULL even though there may be buffers left in the
virtqueue.

This causes poll() to block even though there is data to be read,
this patch fixes this by using will_read_block(port) instead of the
port->inbuf != NULL check.

Signed-off-By: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org

Hans de Goede   authored and   Rusty Russell   commited 2010-09-21 10:54:01 +09:30
6df7aadcd9
virtio: console: Fix crash when port is unplugged and blocked for write
When a program that has a virtio port opened and blocked for a write
operation, a port hot-unplug event will later led to a crash when
SIGTERM was sent to the program. Fix that.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-06-03 22:39:19 +09:30
60e5e0b840
virtio: console: Fix crash when hot-unplugging a port and read is blocked
When removing a port we don't check if a program was blocked for read.
This leads to a crash when SIGTERM is sent to the program after
hot-unplugging the port.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-06-03 22:39:18 +09:30
0047634d3d
drivers/char: Eliminate use after free
In each case, the first argument to send_control_msg or __send_control_msg,
respectively, has either not been successfully allocated or has been freed
at the point of the call.  In the first case, the first argument, port, is
only used to access the portdev and id fields, in order to call
__send_control_msg.  Thus it seems possible instead to call
__send_control_msg directly.  In the second case, the call to
__send_control_msg is moved up to a place where it seems like the first
argument, portdev, has been initialized sufficiently to make the call to
__send_control_msg meaningful.

This has only been compile tested.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@free@
expression E;
position p;
@@
kfree@p(E)

@@
expression free.E, subE<=free.E, E1;
position free.p;
@@

  kfree@p(E)
  ...
(
  subE = E1
|
* E
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Julia Lawall   authored and   Rusty Russell   commited 2010-05-19 22:15:51 +09:30
0643e4c6e4
virtio: console: Accept console size along with resize control message
The VIRTIO_CONSOLE_RESIZE control message sent to us by the host now
contains the new {rows, cols} values for the console. This ensures each
console port gets its own size, and we don't depend on the config-space
rows and cols values at all now.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Christian Borntraeger <borntraeger@de.ibm.com>
CC: linuxppc-dev@ozlabs.org
CC: Kusanagi Kouichi <slash@ac.auone-net.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Amit Shah   authored and   Rusty Russell   commited 2010-05-19 22:15:51 +09:30
8345adbf96