linux.git/drivers/char/virtio_console.c, branch v2.6.37

Char: virtio_console, fix memory leak

2010-11-24T04:51:12+00:00

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 
Cc: Amit Shah 
Cc: virtualization@lists.linux-foundation.org
Cc: Greg Kroah-Hartman 
Signed-off-by: Rusty Russell

virtio: console: Disable lseek(2) for port file operations

2010-10-21T07:14:04+00:00

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 
CC: Arnd Bergmann 
Signed-off-by: Rusty Russell

virtio: console: Send SIGIO in case of port unplug

2010-10-21T07:14:04+00:00

If a port has registered for SIGIO signals, let the application
know that the port is getting unplugged.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: console: Send SIGIO on new data arrival on ports

2010-10-21T07:14:04+00:00

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 
Signed-off-by: Rusty Russell

virtio: console: Send SIGIO to processes that request it for host events

2010-10-21T07:14:03+00:00

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 
Signed-off-by: Rusty Russell

virtio: console: Reference counting portdev structs is not needed

2010-10-21T07:14:03+00:00

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 
Signed-off-by: Rusty Russell

virtio: console: Add reference counting for port struct

2010-10-21T07:14:03+00:00

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 
Signed-off-by: Rusty Russell

virtio: console: Use cdev_alloc() instead of cdev_init()

2010-10-21T07:14:03+00:00

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 
Signed-off-by: Rusty Russell

virtio: console: Add a find_port_by_devt() function

2010-10-21T07:14:03+00:00

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 
Signed-off-by: Rusty Russell

virtio: console: Add a list of portdevs that are active

2010-10-21T07:14:02+00:00

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 
Signed-off-by: Rusty Russell