s390/tty3270: convert lines during output
The length of the screen line is variable with the 3270 protocol. For each attribute (foreground, background color, highlighting etc) we need 3 bytes: the set attribute order, the attribute number, and the value of the attribute. This means that depending on screen content, we might end up 3*3 bytes addtional data for a single character. Allocating the maximum possible amount of memory is quite a lot, and we cannot easily extend the lines by allocating memory because we might get called from atomic context. Failing to extend the memory would also be bad as that would mean that we could miss kernel messages in oom conditions. Therefore move the conversion to a 3270 datastream to tty3270_update(), and use only single line buffer. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> Tested-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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