Hi, Guys:
It was found that the 3.12 kernel tty layer will lose or corrupt data when have a full-duplex communication, especcially in high baudrate, for example 230k for my OMAP5 uart. Eventually I found there is lock missing between copy data to ldisc layer buffer and copy data from the same buffer to user 
space. I believe this issue existed since 3.8 kernel(since this kernel , it start to remove most of the spin-locks) and I didn't find any fix even through 3.17 kernel. This patch was tested to be works great with no any data loss again.


I did try to use the existed lock atomic_read_lock, but it doesn’t work. 



Denis Du