linux.git/drivers/char/virtio_console.c, branch v5.8

virtio: virtio_console: add missing MODULE_DEVICE_TABLE() for rproc serial

2020-07-10T13:12:48+00:00

rproc_serial_id_table lacks an exposure to module devicetable, so
when remoteproc firmware requests VIRTIO_ID_RPROC_SERIAL, no uevent
is generated and no module autoloading occurs.
Add missing MODULE_DEVICE_TABLE() annotation and move the existing
one for VIRTIO_ID_CONSOLE right to the table itself.

Fixes: 1b6370463e88 ("virtio_console: Add support for remoteproc serial")
Cc:  # v3.8+
Signed-off-by: Alexander Lobakin 
Reviewed-by: Amit Shah 
Link: https://lore.kernel.org/r/x7C_CbeJtoGMy258nwAXASYz3xgFMFpyzmUvOyZzRnQrgWCREBjaqBOpAUS7ol4NnZYvSVwmTsCG0Ohyfvta-ygw6HMHcoeKK0C3QFiAO_Q=@pm.me
Signed-off-by: Greg Kroah-Hartman

fs: rename pipe_buf ->steal to ->try_steal

2020-05-20T16:14:10+00:00

And replace the arcane return value convention with a simple bool
where true means success and false means failure.

[AV: braino fix folded in]

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

char: virtio: Replace zero-length array with flexible-array member

2020-02-14T17:16:01+00:00

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva 
Link: https://lore.kernel.org/r/20200211222941.GA7657@embeddedor
Signed-off-by: Greg Kroah-Hartman

Merge tag 'notifications-pipe-prep-20191115' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

2019-11-30T22:12:13+00:00

Pull pipe rework from David Howells:
"This is my set of preparatory patches for building a general
notification queue on top of pipes. It makes a number of significant
changes:

- It removes the nr_exclusive argument from __wake_up_sync_key() as
this is always 1. This prepares for the next step:

- Adds wake_up_interruptible_sync_poll_locked() so that poll can be
woken up from a function that's holding the poll waitqueue
spinlock.

- Change the pipe buffer ring to be managed in terms of unbounded
head and tail indices rather than bounded index and length. This
means that reading the pipe only needs to modify one index, not
two.

- A selection of helper functions are provided to query the state of
the pipe buffer, plus a couple to apply updates to the pipe
indices.

- The pipe ring is allowed to have kernel-reserved slots. This allows
many notification messages to be spliced in by the kernel without
allowing userspace to pin too many pages if it writes to the same
pipe.

- Advance the head and tail indices inside the pipe waitqueue lock
and use wake_up_interruptible_sync_poll_locked() to poke poll
without having to take the lock twice.

- Rearrange pipe_write() to preallocate the buffer it is going to
write into and then drop the spinlock. This allows kernel
notifications to then be added the ring whilst it is filling the
buffer it allocated. The read side is stalled because the pipe
mutex is still held.

- Don't wake up readers on a pipe if there was already data in it
when we added more.

- Don't wake up writers on a pipe if the ring wasn't full before we
removed a buffer"

* tag 'notifications-pipe-prep-20191115' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
pipe: Remove sync on wake_ups
pipe: Increase the writer-wakeup threshold to reduce context-switch count
pipe: Check for ring full inside of the spinlock in pipe_write()
pipe: Remove redundant wakeup from pipe_write()
pipe: Rearrange sequence in pipe_write() to preallocate slot
pipe: Conditionalise wakeup in pipe_read()
pipe: Advance tail pointer inside of wait spinlock in pipe_read()
pipe: Allow pipes to have kernel-reserved slots
pipe: Use head and tail pointers for the ring, not cursor and length
Add wake_up_interruptible_sync_poll_locked()
Remove the nr_exclusive argument from __wake_up_sync_key()
pipe: Reduce #inclusion of pipe_fs_i.h

virtio_console: allocate inbufs in add_port() only if it is needed

2019-11-19T10:13:49+00:00

When we hot unplug a virtserialport and then try to hot plug again,
it fails:

(qemu) chardev-add socket,id=serial0,path=/tmp/serial0,server,nowait
(qemu) device_add virtserialport,bus=virtio-serial0.0,nr=2,\
                  chardev=serial0,id=serial0,name=serial0
(qemu) device_del serial0
(qemu) device_add virtserialport,bus=virtio-serial0.0,nr=2,\
                  chardev=serial0,id=serial0,name=serial0
kernel error:
  virtio-ports vport2p2: Error allocating inbufs
qemu error:
  virtio-serial-bus: Guest failure in adding port 2 for device \
                     virtio-serial0.0

This happens because buffers for the in_vq are allocated when the port is
added but are not released when the port is unplugged.

They are only released when virtconsole is removed (see a7a69ec0d8e4)

To avoid the problem and to be symmetric, we could allocate all the buffers
in init_vqs() as they are released in remove_vqs(), but it sounds like
a waste of memory.

Rather than that, this patch changes add_port() logic to ignore ENOSPC
error in fill_queue(), which means queue has already been filled.

Fixes: a7a69ec0d8e4 ("virtio_console: free buffers after reset")
Cc: mst@redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Laurent Vivier 
Signed-off-by: Michael S. Tsirkin

pipe: Use head and tail pointers for the ring, not cursor and length

2019-10-31T15:12:34+00:00

Convert pipes to use head and tail pointers for the buffer ring rather than
pointer and length as the latter requires two atomic ops to update (or a
combined op) whereas the former only requires one.

 (1) The head pointer is the point at which production occurs and points to
     the slot in which the next buffer will be placed.  This is equivalent
     to pipe->curbuf + pipe->nrbufs.

     The head pointer belongs to the write-side.

 (2) The tail pointer is the point at which consumption occurs.  It points
     to the next slot to be consumed.  This is equivalent to pipe->curbuf.

     The tail pointer belongs to the read-side.

 (3) head and tail are allowed to run to UINT_MAX and wrap naturally.  They
     are only masked off when the array is being accessed, e.g.:

	pipe->bufs[head & mask]

     This means that it is not necessary to have a dead slot in the ring as
     head == tail isn't ambiguous.

 (4) The ring is empty if "head == tail".

     A helper, pipe_empty(), is provided for this.

 (5) The occupancy of the ring is "head - tail".

     A helper, pipe_occupancy(), is provided for this.

 (6) The number of free slots in the ring is "pipe->ring_size - occupancy".

     A helper, pipe_space_for_user() is provided to indicate how many slots
     userspace may use.

 (7) The ring is full if "head - tail >= pipe->ring_size".

     A helper, pipe_full(), is provided for this.

Signed-off-by: David Howells

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details you
  should have received a copy of the gnu general public license along
  with this program if not write to the free software foundation inc
  59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Richard Fontana 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman

virtio_console: initialize vtermno value for ports

2019-03-27T16:28:24+00:00

For regular serial ports we do not initialize value of vtermno
variable. A garbage value is assigned for non console ports.
The value can be observed as a random integer with [1].

[1] vim /sys/kernel/debug/virtio-ports/vport*p*

This patch initialize the value of vtermno for console serial
ports to '1' and regular serial ports are initiaized to '0'.

Reported-by: siliu@redhat.com
Signed-off-by: Pankaj Gupta 
Signed-off-by: Greg Kroah-Hartman

char: virtio: Change to use DEFINE_SHOW_ATTRIBUTE macro

2018-12-06T14:42:18+00:00

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Yangtao Li 
Signed-off-by: Greg Kroah-Hartman

virtio: virtconsole: Use seq_file for debugfs operations

2018-07-16T10:03:53+00:00

Simplifies the code and is more conventional to what's used in the rest
of the kernel for debugfs ops.

Signed-off-by: Tuomas Tynkkynen 
Reviewed-by: Amit Shah 
Signed-off-by: Greg Kroah-Hartman