[PATCH V6 2/5] nvmet: add passthru admin timeout value attr

[Sagi Grimberg]

On 11/4/20 12:37 PM, Chaitanya Kulkarni wrote:
> NVMeOF controller in the passsthru mode is capable of handling wide set
> of admin commands including Vender unique passhtru admin comands (VUAC).
> 
> The VUACs are used to read the large driver logs and can take longer
> than default NVMe commands, that is for passthru requests the timeout
> value may differ from the passthru controller's default timeout values
> (nvme-core:admin_timeout).
> 
> Add a configfs attribute so that user can set the admin timeout values.
> In case if this configfs value is not set nvme_alloc_request() will set
> use the ADMIN_TIMEOUT value.
> 
> This attribute setting is only allowed when ctrl is disable to avoid
> rcu calls in the fast path, in future when needed we can always make it
> fast path friendly using RCU.

What's not safe here? a command will get a single timeout, either the
old one or the new one, not sure what can go wrong here...