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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Tyrel Datwyler <tyreld@linux.ibm.com>
Cc:     benh@kernel.crashing.org, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/pseries: Add shutdown() to vio_driver and vio_bus
In-Reply-To: <f326def4-0db0-f924-1700-dd7be3154153@linux.ibm.com>
References: <20210402001325.939668-1-tyreld@linux.ibm.com>
 <f326def4-0db0-f924-1700-dd7be3154153@linux.ibm.com>
Date:   Sat, 17 Apr 2021 22:30:14 +1000
Message-ID: <87im4ldrft.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
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Precedence: bulk

Tyrel Datwyler <tyreld@linux.ibm.com> writes:
> On 4/1/21 5:13 PM, Tyrel Datwyler wrote:
>> Currently, neither the vio_bus or vio_driver structures provide support
>> for a shutdown() routine.
>> 
>> Add support for shutdown() by allowing drivers to provide a
>> implementation via function pointer in their vio_driver struct and
>> provide a proper implementation in the driver template for the vio_bus
>> that calls a vio drivers shutdown() if defined.
>> 
>> In the case that no shutdown() is defined by a vio driver and a kexec is
>> in progress we implement a big hammer that calls remove() to ensure no
>> further DMA for the devices is possible.
>> 
>> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
>> ---
>
> Ping... any comments, problems with this approach?

The kexec part seems like a bit of a hack.

It also doesn't help for kdump, when none of the shutdown code is run.

How many drivers do we have? Can we just implement a proper shutdown for
them?

cheers