mirror of https://gitee.com/openkylin/linux.git
73a6fdc48b
When unlocking a spinlock, we use the sev instruction to signal other CPUs waiting on the lock. Since sev is not a memory access instruction, we require a dsb in order to ensure that the sev is not issued ahead of the store placing the lock in an unlocked state. However, as sev is only concerned with other processors in a multiprocessor system, we can restrict the scope of the preceding dsb to the inner-shareable domain. Furthermore, we can restrict the scope to consider only stores, since there are no independent loads on the unlock path. A side-effect of this change is that a spin_unlock operation no longer forces completion of pending TLB invalidation, something which we rely on when unlocking runqueues to ensure that CPU migration during TLB maintenance routines doesn't cause us to continue before the operation has completed. This patch adds the -ishst suffix to the ARMv7 definition of dsb_sev() and adds an inner-shareable dsb to the context-switch path when running a preemptible, SMP, v7 kernel. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> |
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