Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

From: Tadeusz Struk
Date: Fri Aug 10 2018 - 14:56:50 EST

On 08/10/2018 11:48 AM, James Bottomley wrote:
> On Fri, 2018-08-10 at 11:21 -0700, Tadeusz Struk wrote:
>> and the feedback I got from Jason was:
>> "I wonder if it is worth creating this when the first file is
>> opened.. Lots of systems have TPMs but few use the userspace.."
>> so I changed this to allocate the WQ on first open. I think it makes
>> sense, but I leave it to you to decide.
> If the reason is to not create a wq unless it's needed, shouldn't the
> condition actually be first open with flag O_NONBLOCK?

Not really because one can do:

int fd = open("/dev/tpm0", O_RDWR);
fcntl(fd, F_SETFL, O_NONBLOCK);