[Skiboot] [PATCH v2 12/52] libflash/ipmi-hiomap: Overhaul event handling

[Vasant Hegde]

On 02/21/2019 11:58 AM, Andrew Jeffery wrote:
> Reworking the event handling was inspired by a bug report by Vasant
> where the host would get wedged on multiple flash access attempts in the
> face of a persistent error state on the BMC-side. The cause of this bug
> was the early-exit based on ctx->update, which erronously assumed that
> all events had been completely handled in prior calls to
> ipmi_hiomap_handle_events(). This is not true if e.g.
> HIOMAP_E_DAEMON_READY is clear in the prior calls.
> 
> Regardless, there were other correctness and efficiency problems with
> the handling strategy:
> 
> * Ack-able event state was not restored in the face of errors in the
>    process of re-establishing protocol state
> 
> * It forced needless window restoration with respect to the context in
>    which ipmi_hiomap_handle_events() was called.
> 
> * Tests for HIOMAP_E_DAEMON_READY and HIOMAP_E_FLASH_LOST were redundant
>    with the overhauled error handling introduced in the previous patch
> 
> Fix all of the above issues and add comments to explain the event
> handling flow.
> 
> Tests for correctness follow later in the series.
> 
> Cc: stable
> Cc: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>

Looks like your mail client did not like me.  I was not CCed.


> Signed-off-by: Andrew Jeffery <andrew at aj.id.au>

I have reviewed/tested this patch. Looks good. This will help to reduce the the 
hard lockup issue.

-Vasant