From: Paul E. McKenney Date: Thu, 13 Feb 2014 04:19:47 +0000 (-0800) Subject: Documentation/memory-barriers.txt: Need barriers() for some control dependencies X-Git-Tag: v3.15-rc1~183^2~1^2~4 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9b2b3bf53124dca4ac815bd2fca53a31e5e262bd;p=pandora-kernel.git Documentation/memory-barriers.txt: Need barriers() for some control dependencies Current compilers can "speculate" stores in the case where both legs of the "if" statement start with identical stores. Because the stores are identical, the compiler knows that the store will unconditionally execute regardless of the "if" condition, and so the compiler is within its rights to hoist the store to precede the condition. Such hoisting destroys the control-dependency ordering. This ordering can be restored by placing a barrier() at the beginning of each leg of the "if" statement. This commit adds this requirement to the control-dependencies section. Signed-off-by: Paul E. McKenney --- Reading git-diff-tree failed