Date: Thu, 19 Oct 2017 03:36:20 +0200 From: "Jason A. Donenfeld" <Jason@...c4.com> To: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> Cc: "Tobin C. Harding" <me@...in.cc>, kernel-hardening@...ts.openwall.com, "Theodore Ts'o" <tytso@....edu>, Linus Torvalds <torvalds@...ux-foundation.org>, Kees Cook <keescook@...omium.org>, Paolo Bonzini <pbonzini@...hat.com>, Tycho Andersen <tycho@...ker.com>, "Roberts, William C" <william.c.roberts@...el.com>, Tejun Heo <tj@...nel.org>, Jordan Glover <Golden_Miller83@...tonmail.ch>, Greg KH <gregkh@...uxfoundation.org>, Petr Mladek <pmladek@...e.com>, Joe Perches <joe@...ches.com>, Ian Campbell <ijc@...lion.org.uk>, Sergey Senozhatsky <sergey.senozhatsky@...il.com>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <wilal.deacon@....com>, Steven Rostedt <rostedt@...dmis.org>, Chris Fries <cfries@...gle.com>, Dave Weinstein <olorin@...gle.com>, Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v5] printk: hash addresses printed with %p On Thu, Oct 19, 2017 at 3:31 AM, Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> wrote: > On (10/19/17 03:03), Jason A. Donenfeld wrote: > [..] >> 1) Go back to the spinlock yourself. > > so we ruled out NMI deadlocks? Oh, right. No, I haven't thought through this enough to rule it out. Indeed if that's an issue, the locks in the _once code will also be an issue. So if locking is totally impossible, then a race-free way of doing this is with a tri-state compare and exchange. Things are either: in state 1: no key, state 2: getting key, state 3: have key. If state 1 or 2, print the placeholder token. If state 3, do the hashing.
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.