On Wed, Oct 17, 2018 at 01:32:51PM +0900, Sergey Senozhatsky wrote: > This probably will be a bit more hairy. logbuf is written to by many > sources and is read from by many sides, including user-space [both read() > and write()]. So we will need more flags/magic around memcpy(). A simple, > "grab the logbuf entry, set the proper offset to point to the next available > logbuf record and then do memcpy()" won't suffice. We need a flag for > "memcpy() complete, we can read this entry". Otherwise: Sure, but lockless buffers mostly have reserve and commit stages anyway. Exactly to avoid that problem. > All right. OK. So we are on the same page here: > - Have more opinions on this. People please speak out. > - Have clear "let's do it" from Cc-ed people. > > > If we are really doing this, then let's split it and have > incremental changes. Namely, what I suggest is: I'd start by replacing logbuf with the lockless buffer and ripping out the current nmi/safe/etc.. bollocks. There is absolutely no point what so ever in doing anything until that is sorted. After that, move the console output to a kthread, but keep earlycon (if set) synchronous. Also avoid the whole panic/warn special case when earlycon is set, no point in doing dodgy crap when you know you have a good option already.
