254e4e5b77
When a DMA request using bounce pages completes, a swi is triggered to schedule pending DMA requests using the just-freed bounce pages. For a long time this bus_dma swi has been tied to a "virtual memory" swi (swi_vm). However, all of the swi_vm implementations are the same and consist of checking a flag (busdma_swi_pending) which is always true and if set calling busdma_swi. I suspect this dates back to the pre-SMPng days and that the intention was for swi_vm to serve as a mux. However, in the current scheme there's no need for the mux. Instead, remove swi_vm and vm_ih. Each bus_dma implementation that uses bounce pages is responsible for creating its own swi (busdma_ih) which it now schedules directly. This swi invokes busdma_swi directly removing the need for busdma_swi_pending. One consequence is that the swi now works on RISC-V which had previously failed to invoke busdma_swi from swi_vm. Reviewed by: imp, kib Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D33447 |
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