Re: [PATCH] raid5: panic() on dma_wait_for_async_tx() error
From: Dan Williams <hidden>
Date: 2012-11-19 05:22:39
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On 11/18/12 5:06 PM, "NeilBrown" [off-list ref] wrote:
Hi Dan, could you comment on this please? Would it make sense to arrange for errors to propagate up? Or should we arrange to do a software-fallback in the dma engine is a problem? What sort of things can cause error here anyway?
Propagating up is missing reliable "dma abort" operation. In these cases the engine failed to complete due to hardware hang / driver bug, or has hit a memory error (uncorrectable even with software fallback). This originally should have been using async_tx_quiesce() which also does the panic. The engines that I have worked with have either lacked support for aborting, or were otherwise unable to recover from a hardware hang. However, for engines that do support error recovery they should be able to hide the failure from the upper layers. -- Dan