• Paul E. McKenney's avatar
    doc: Add load/store guarantees to Documentation/atomic-ops.txt · 182dd4b2
    Paul E. McKenney authored
    An IRC discussion uncovered many conflicting opinions on what types
    of data may be atomically loaded and stored.  This commit therefore
    calls this out the official set: pointers, longs, ints, and chars (but
    not shorts).  This commit also gives some examples of compiler mischief
    that can thwart atomicity.
    Please note that this discussion is relevant to !SMP kernels if
    CONFIG_PREEMPT=y: preemption can cause almost as much trouble as can SMP.
    Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Richard Henderson <rth@twiddle.net>
    Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
    Cc: Matt Turner <mattst88@gmail.com>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
    Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
    Cc: Mike Frysinger <vapier@gentoo.org>
    Cc: Mikael Starvik <starvik@axis.com>
    Cc: Jesper Nilsson <jesper.nilsson@axis.com>
    Cc: David Howells <dhowells@redhat.com>
    Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
    Cc: Richard Kuo <rkuo@codeaurora.org>
    Cc: Jes Sorensen <jes@sgi.com>
    Cc: Hirokazu Takata <takata@linux-m32r.org>
    Cc: Geert Uytterhoeven <geert@linux-m68k.org>
    Cc: Michal Simek <monstr@monstr.eu>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
    Cc: Jonas Bonn <jonas@southpole.se>
    Cc: Kyle McMartin <kyle@mcmartin.ca>
    Cc: Helge Deller <deller@gmx.de>
    Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    Cc: Chen Liqin <liqin.chen@sunplusct.com>
    Cc: Lennox Wu <lennox.wu@gmail.com>
    Cc: Paul Mundt <lethal@linux-sh.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Chris Metcalf <cmetcalf@tilera.com>
    Cc: Jeff Dike <jdike@addtoit.com>
    Cc: Richard Weinberger <richard@nod.at>
    Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Chris Zankel <chris@zankel.net>
atomic_ops.txt 21.6 KB