RE: [PATCH] cifs: Remove locking in smb2_verify_signature() when calculating SMB2/SMB3 signature on receiving packets

[Long Li]

>Subject: Re: [PATCH] cifs: Remove locking in smb2_verify_signature() when
>calculating SMB2/SMB3 signature on receiving packets
>
>longli@xxxxxxxxxxxxxxxxx writes:
>> On the sending and receiving paths, CIFS uses the same cypto data
>> structures to calculate SMB2/SMB3 packet signatures. A lock on the
>> receiving path is necessary to control shared access to crypto data
>> structures. This lock degrades performance because it races with the
>sending path.
>>
>> Define separate crypto data structures for sending and receiving paths
>> and remove this lock.
>
>Something I've often wondered: why do we keep crypto state in the server
>structure instead of creating it as needed in the caller stack (thus avoiding the
>need for locks). AFAIK there's no state that need to be kept between
>signing/encrypting calls beside the access to keys. Is it that expensive to
>create/release?

My guess is that crypto_alloc_shash() is a heavy call?

>
>Cheers,
>--
>AurÃlien Aptel / SUSE Labs Samba Team
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