linux-kernel - Re: [PATCH] tpm: add support for partial reads

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Message-ID: <ee0f0ccf-f757-a7d4-bf55-316f81fb490b@intel.com>
Date:   Mon, 23 Jul 2018 16:42:38 -0700
From:   Tadeusz Struk <tadeusz.struk@...el.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     James Bottomley <James.Bottomley@...senPartnership.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: add support for partial reads

On 07/23/2018 03:08 PM, Jason Gunthorpe wrote:
> On Mon, Jul 23, 2018 at 03:00:20PM -0700, Tadeusz Struk wrote:
>> On 07/23/2018 02:56 PM, Jason Gunthorpe wrote:
>>> The proposed patch doesn't clear the data_pending if the entire buffer
>>> is not consumed, so of course it is ABI breaking, that really isn't OK.
>> The data_pending will be cleared by the timeout handler if the user doesn't
>> read the response fully before the timeout expires. The is the same situation
>> if the user would not read the response at all.
> That causes write() to fail with EBUSY
> 
> NAK from me on breaking the ABI like this

What if we introduce this new behavior only for the non-blocking mode
as James suggested? Or do you have some other suggestions?

Thanks,
-- 
Tadeusz