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From: | Evgeny Yakovlev |
Subject: | Re: [Qemu-devel] [PATCH 2/3] ide: ignore retry_unit check for non-retry operations |
Date: | Wed, 29 Jun 2016 11:35:04 +0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 |
On 28.06.2016 23:56, Paolo Bonzini wrote:
On 24/06/2016 17:06, Denis V. Lunev wrote:When doing DMA request ide/core.c will set s->retry_unit to s->unit in ide_start_dma. When dma completes ide_set_inactive sets retry_unit to -1. After that ide_flush_cache runs and fails thanks to blkdebug. ide_flush_cb calls ide_handle_rw_error which asserts that s->retry_unit == s->unit. But s->retry_unit is still -1 after previous DMA completion and flush does not use anything related to retry.Wouldn't the assertion fail for a PIO read/write too? Perhaps retry_unit should be set to s->unit in ide_transfer_start too.
If PIO follows DMA and fails then yes, it looks like it will trigger an assert. I am not sure about setting retry_unit in ide_transfer_start. It looks like currently only DMA I/O entries touch retry_unit at all. Does that mean that PIO, flush, etc do not support retries by design and we need to add more exceptions to assert check or is it a real bug in how retries are initialized?
Paolo
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