From 88ec11b0f82b517b4f1c13f57096db5c8872fccb Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Thu, 13 Nov 2014 15:47:46 +0530 Subject: ARC: document memory clobber in irq control macros Signed-off-by: Vineet Gupta diff --git a/arch/arc/include/asm/irqflags.h b/arch/arc/include/asm/irqflags.h index 742816f..27ecc69 100644 --- a/arch/arc/include/asm/irqflags.h +++ b/arch/arc/include/asm/irqflags.h @@ -41,6 +41,15 @@ /****************************************************************** * IRQ Control Macros + * + * All of them have "memory" clobber (compiler barrier) which is needed to + * ensure that LD/ST requiring irq safetly (R-M-W when LLSC is not available) + * are redone after IRQs are re-enabled (and gcc doesn't reuse stale register) + * + * Noted at the time of Abilis Timer List corruption + * Orig Bug + Rejected solution : https://lkml.org/lkml/2013/3/29/67 + * Reasoning : https://lkml.org/lkml/2013/4/8/15 + * ******************************************************************/ /* -- cgit v0.10.2