linux-kernel - Re: [PATCH 4/5] locking/lockdep: Reuse free chain

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <dab58211-8d31-3b16-c1f1-51badfa8e210@redhat.com>
Date:   Fri, 13 Dec 2019 11:05:12 -0500
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...hat.com>, Will Deacon <will.deacon@....com>,
        linux-kernel@...r.kernel.org, Bart Van Assche <bvanassche@....org>
Subject: Re: [PATCH 4/5] locking/lockdep: Reuse free chain_hlocks entries

On 12/13/19 11:02 AM, Waiman Long wrote:
> That is an interesting idea. It will eliminate the need of a separate
> array to track the free chain_hlocks. However, if there are n chains
> available, it will waste about 3n bytes of storage, on average.
>
> I have a slightly different idea. I will enforce a minimum allocation
> size of 2. For a free block, the first 2 hlocks for each allocation
> block will store a 32-bit integer (hlock[0] << 16)|hlock[1]:
>
> Bit 31: always 1
> Bits 24-30: block size
> Bits 0-23: index to the next free block.
>
> In this way, the wasted space will be k bytes where k is the number of
The wasted space should be 2k bytes. My mistake.
> 1-entry chains. I don't think merging adjacent blocks will be that
> useful at this point. We can always add this capability later on if it
> is found to be useful.

Cheers,
Longman