Hi Yunfei,
Since __alloc_and_insert_iova_range fail will set the current alloc iova size to max32_alloc_size (iovad->max32_alloc_size = size), when the retry is executed into the __alloc_and_insert_iova_range function, the retry action will be blocked by the check condition (size >= iovad->max32_alloc_size) and goto iova32_full directly, causes the action of retry regular alloc iova in __alloc_and_insert_iova_range to not actually be executed.
Based on the above, so need reset max32_alloc_size before retry alloc iova when alloc iova fail, that is set the initial dma_32bit_pfn value of iovad to max32_alloc_size, so that the action of retry alloc iova in __alloc_and_insert_iova_range can be executed.
Have you observed this making any difference in practice?
Given that both free_cpu_cached_iovas() and free_global_cached_iovas() call iova_magazine_free_pfns(), which calls remove_iova(), which calls __cached_rbnode_delete_update(), I'm thinking no...
Robin.
Like Robin pointed out, if some cached iovas are freed by free_global_cached_iovas()/free_cpu_cached_iovas(), the max32_alloc_size should be reset to iovad->dma_32bit_pfn.
If no cached iova is freed, resetting max32_alloc_size before the retry allocation only give us a retry. Is it possible that other users free their iovas during the additional retry?
alloc_iova_fast() retry: alloc_iova() // failed, iovad->max32_alloc_size = size free_cpu_cached_iovas() iova_magazine_free_pfns() remove_iova() __cached_rbnode_delete_update() iovad->max32_alloc_size = iovad->dma_32bit_pfn // reset free_global_cached_iovas() iova_magazine_free_pfns() remove_iova() __cached_rbnode_delete_update() iovad->max32_alloc_size = iovad->dma_32bit_pfn // reset goto retry;
thanks, Miles