linux-stable.git/drivers/tty/vt, branch v5.1.2

vt: fix cursor when clearing the screen

2019-04-17T12:45:15+00:00

The patch a6dbe4427559 ("vt: perform safe console erase in the right
order") introduced a bug. The conditional do_update_region() was
replaced by a call to update_region() that does contain the conditional
already, but with unwanted extra side effects such as restoring the cursor
drawing.

In order to reproduce the bug:
- use framebuffer console with the AMDGPU driver
- type "links" to start the console www browser
- press 'q' and space to exit links

Now the cursor will be permanently visible in the center of the
screen. It will stay there until something overwrites it.

The bug goes away if we change update_region() back to the conditional
do_update_region().

[ nico: reworded changelog ]

Signed-off-by: Mikulas Patocka 
Reviewed-by: Nicolas Pitre 
Cc: stable@vger.kernel.org
Fixes: a6dbe4427559 ("vt: perform safe console erase in the right order")
Signed-off-by: Greg Kroah-Hartman

vt: perform safe console erase in the right order

2019-02-12T09:46:11+00:00

Commit 4b4ecd9cb853 ("vt: Perform safe console erase only once") removed
what appeared to be an extra call to scr_memsetw(). This missed the fact
that set_origin() must be called before clearing the screen otherwise
old screen content gets restored on the screen when using vgacon. Let's
fix that by moving all the scrollback handling to flush_scrollback()
where it logically belongs, and invoking it before the actual screen
clearing in csi_J(), making the code simpler in the end.

Reported-by: Matthew Whitehead 
Signed-off-by: Nicolas Pitre 
Tested-by: Matthew Whitehead 
Fixes: 4b4ecd9cb853 ("vt: Perform safe console erase only once")
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

Merge 5.0-rc4 into tty-next

2019-01-28T07:22:00+00:00

We need the tty and serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman

vt: ignore sequences that contain ':' in parameters.

2019-01-18T12:57:27+00:00

csi sequences can contain subparameters delimited by ':' characters. For
now just ignore the whole sequence in this case. Such sequences are used by
more capable terminal implementations with T.416 high color modes or
extended underline rendition attributes.

Also ignore sequences with private use characters '?', '>', '='
and '>' that are not at the initial position.

Signed-off-by: Martin Hostettler 
Signed-off-by: Greg Kroah-Hartman

vt: ignore csi sequences with intermediate characters.

2019-01-18T12:57:27+00:00

Various csi sequences contain intermediate characters between the
parameters and the final character. Introduce a additional state that
cleanly ignores these sequences.

This allows the vt to ignore these sequences used by more capable
terminal implementations such as "request mode", etc.

Signed-off-by: Martin Hostettler 
Signed-off-by: Greg Kroah-Hartman

vt: Implement parsing for >, =, < private sequences.

2019-01-18T12:56:41+00:00

Private sequences can start with '>', '=' and (in theory) '<'.
Implement correct parsing for these. The newly parsable sequences are
cleanly ignored as it is customary with terminal emulators.

This allows the vt to ignore various sequences used by more capable
terminal implementations such as "Secondary Device Attributes",
"Tertiary Device Attributes" and various advanced configuration commands
that don't have dedicated terminfo entries.

Signed-off-by: Martin Hostettler 
Signed-off-by: Greg Kroah-Hartman

vt: refactor vc_ques to allow of other private sequences.

2019-01-18T12:52:41+00:00

The vc_ques keeps track if a csi sequence is a private DEC control
function beginning with '?'. Nowadays some private control functions
begin with '>' and '='. Switch the code to instead use a new 3-bit
vc_priv that allows for all private use parameter prefixes.

Signed-off-by: Martin Hostettler 
Signed-off-by: Greg Kroah-Hartman

vt: annotate implicit fall throughs

2019-01-18T12:48:52+00:00

There is a plan to build the kernel with -Wimplicit-fallthrough and
these places in the code produced warnings (W=1). Fix them up.

This commit remove the following warning:

  drivers/tty/vt/vt.c:2112:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
  drivers/tty/vt/vt.c:2237:6: warning: this statement may fall through [-Wimplicit-fallthrough=]

Signed-off-by: Mathieu Malaterre 
Acked-by: Gustavo A. R. Silva 
Signed-off-by: Greg Kroah-Hartman

vcs: restore and document initial POLLPRI event

2019-01-18T12:48:52+00:00

Restore and document the forced initial POLLPRI event reporting when
poll() is used for the first time. This used to be the implemented
behavior before recent changes. Because of the way poll() is implemented,
this prevents losing an event happening between the last read() and the
first poll() invocation.

Since poll() for /dev/vcs* was not always supported, user space probes
for its availability as follows:

	int fd = open("/dev/vcsa", O_RDONLY);
	struct pollfd p = { .fd = fd, .events = POLLPRI };
	available = (poll(&p, 1, 0) == 1);

Semantically, it makes sense to signal the first event as such even if
it might be spurious. The screen could be modified, and modified back
to its initial state before we get to read it, so users must be prepared
for that anyway.

Signed-off-by: Nicolas Pitre 
Signed-off-by: Greg Kroah-Hartman

vcs: fasync(): make it consistent with poll()

2019-01-18T12:47:55+00:00

We use POLLPRI not POLLIN to wait for data with poll() as there is
never any incoming data stream per se. Let's use the same semantic
with fasync() for consistency, including the fact that a vt may go away.

No known user space ever relied on the SIGIO reason so far, let alone
FASYNC, so the risk of breakage is pretty much nonexistent.

Signed-off-by: Nicolas Pitre 
Signed-off-by: Greg Kroah-Hartman