rcu: Eliminate signed overflow in synchronize_rcu_expedited()
In the C language, signed overflow is undefined. It is true that twos-complement arithmetic normally comes to the rescue, but if the compiler can subvert this any time it has any information about the values being compared. For example, given "if (a - b > 0)", if the compiler has enough information to realize that (for example) the value of "a" is positive and that of "b" is negative, the compiler is within its rights to optimize to a simple "if (1)", which might not be what you want. This commit therefore converts synchronize_rcu_expedited()'s work-done detection counter from signed to unsigned. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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