kernel.git/drivers/char/virtio_console.c, branch linux-2.6.37.y

virtio: console: Don't access vqs if device was unplugged

2011-03-14T21:17:31Z

commit d7a62cd0332115d4c7c4689abea0d889a30d8349 upstream. 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 Signed-off-by: Amit Shah Signed-off-by: Rusty Russell Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

virtio: console: Wake up outvq on host notifications

2011-02-17T23:14:31Z

commit 2770c5ea501be69989a7acf54ec4cb3554c47191 upstream. The outvq needs to be woken up on host notifications so that buffers consumed by the host can be reclaimed, outvq freed, and application writes may proceed again. The need for this is now finally noticed when I have qemu patches ready to use nonblocking IO and flow control. CC: Hans de Goede Signed-off-by: Amit Shah Signed-off-by: Rusty Russell Acked-by: Hans de Goede Signed-off-by: Greg Kroah-Hartman

Char: virtio_console, fix memory leak

2010-11-24T04:51:12Z

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

2010-10-21T07:14:04Z

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

2010-10-21T07:14:04Z

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

2010-10-21T07:14:04Z

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

2010-10-21T07:14:03Z

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

2010-10-21T07:14:03Z

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

2010-10-21T07:14:03Z

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()

2010-10-21T07:14:03Z

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