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authorVineet Gupta <vgupta@synopsys.com>2014-11-13 15:47:46 +0530
committerVineet Gupta <vgupta@synopsys.com>2014-12-12 16:02:46 +0530
commit88ec11b0f82b517b4f1c13f57096db5c8872fccb (patch)
treef119899229726c594668a6ac4c50df6a79cbcaca /arch/arc
parent9fb92eb1160d7e967f233cdfe2b718acff325b6e (diff)
downloadlinux-stericsson-88ec11b0f82b517b4f1c13f57096db5c8872fccb.tar.gz
ARC: document memory clobber in irq control macros
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/include/asm/irqflags.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arc/include/asm/irqflags.h b/arch/arc/include/asm/irqflags.h
index 742816f1b210..27ecc6975a58 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
+ *
******************************************************************/
/*