• Li Zhong's avatar
    KVM: PPC: Book 3S: XICS: Don't lock twice when checking for resend · 21acd0e4
    Li Zhong authored
    This patch improves the code that takes lock twice to check the resend flag
    and do the actual resending, by checking the resend flag locklessly, and
    add a boolean parameter check_resend to icp_[rm_]deliver_irq(), so the
    resend flag can be checked in the lock when doing the delivery.
    
    We need make sure when we clear the ics's bit in the icp's resend_map, we
    don't miss the resend flag of the irqs that set the bit. It could be
    ordered through the barrier in test_and_clear_bit(), and a newly added
    wmb between setting irq's resend flag, and icp's resend_map.
    Signed-off-by: default avatarLi Zhong <zhong@linux.vnet.ibm.com>
    Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
    21acd0e4
book3s_hv_rm_xics.c 23.6 KB