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    Subject[PATCH tip/core/rcu 4/9] rcu: Remove redundant offline check
    Date
    From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

    Because offline CPUs are propagated up the rcu_node tree's ->qsmaskinit
    bits just before each grace period starts, the ->qsmaskinit bit cannot
    be clear when the corresponding ->qsmask bit is set. Furthermore, this
    condition used to correspond to a CPU that was on its way offline, and
    making RCU's notion of an offline CPU more precise has eliminated this
    situation. This commit therefore removes the now-redundant offline
    check from force_qs_rnp().

    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    ---
    kernel/rcu/tree.c | 2 --
    1 file changed, 2 deletions(-)

    diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
    index 20aeb6f9fe38..1eb1029a5464 100644
    --- a/kernel/rcu/tree.c
    +++ b/kernel/rcu/tree.c
    @@ -2747,8 +2747,6 @@ static void force_qs_rnp(struct rcu_state *rsp,
    bit = 1;
    for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
    if ((rnp->qsmask & bit) != 0) {
    - if ((rnp->qsmaskinit & bit) == 0)
    - *isidle = false; /* Pending hotplug. */
    if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
    mask |= bit;
    }
    --
    1.8.1.5


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