On Sat, Dec 10, 2016 at 04:16:43PM +0800, Herbert Xu wrote: > Why did you drop me from the CC list when you were replying to > my email? > Sorry --- this thread is Cc'ed to the kernel-hardening mailing list (which was somewhat recently revived), and I replied to the email that reached me from there. It looks like it currently behaves a little differently from the vger mailing lists, in that it replaces "Reply-To" with the address of the mailing list itself rather than the sender. So that's how you got dropped. It also seems to add a prefix to the subject... I > >> Are you sure? Any instance of *_ON_STACK must only be used with > >> sync algorithms and most drivers under drivers/crypto declare > >> themselves as async. > > > > Why exactly is that? Obviously, it wouldn't work if you returned from the stack > > frame before the request completed, but does anything stop someone from using an > > *_ON_STACK() request and then waiting for the request to complete before > > returning from the stack frame? > > The *_ON_STACK variants (except SHASH of course) were simply hacks > to help legacy crypto API users to cope with the new async interface. > In general we should avoid using the sync interface when possible. > > It's a bad idea for the obvious reason that most of our async > algorithms want to DMA and that doesn't work very well when you're > using memory from the stack. Sure, I just feel that the idea of "is this algorithm asynchronous?" is being conflated with the idea of "does this algorithm operate on physical memory?". Also, if *_ON_STACK are really not allowed with asynchronous algorithms can there at least be a comment or a WARN_ON() to express this? Thanks, Eric -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>