On 12/10/2014 01:50 PM, Jiri Slaby wrote: > On 12/10/2014, 07:38 PM, Denis Du wrote: >> >> Hi, Guys: > > Hi, are you sending this using some robot? I think I have seen like ten > copies of this patch already. > >> It was found that the 3.12 kernel tty layer will lose or corrupt data >> when have a full-duplex communication, especially in high baud rate, 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 on 3.12 kernel. >> >> This patch was built for the latest kernel, but I cannot test it. >> Somebody may give a test. >> >> I did try to use the existed lock atomic_read_lock, but it doesn’t work. > > Anyway, adding Peter Hurley to CC who was working on eliminating locks > from this code lately. More precisely since 3.12 we have no locks there, > which would explain why are you seeing it starting 3.12.
Yeah, sorry. A new version of gcc for ARM exposed the lack of barriers for the head pointer in raw mode. I got tied up on something else, but this is my #1 priority now. I hope to have something testable in the next day or two. Sorry for the delay. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
