openwall / openwall/john

Review OpenCL format's non-calling of init() in loader when using --fork

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maintenance/cleanup RFC / discussion
Dominant language
C
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Description

https://github.com/openwall/john/issues/4426#issuecomment-720702598

How/why do we get away with not calling fmt_init when options.acc_devices->count && options.fork && strstr(alt->params.label, "-opencl"), or in plain english "running soon-to-be-forked with a GPU format" (a.k.a poor man's multi-GPU support)?

Is it just post-poned? Are we relying on some undocumented (non-)property of all current OpenCL formats? What property? I think many formats don't actually require an init() but we should document what we are relying on here.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked issue 4426 comment, then trace the loader condition involving options.acc_devices, options.fork, the OpenCL label, and fmt_init. Compare the relevant OpenCL formats to determine the assumed initialization property; done means the behavior and its rationale are documented or the missing initialization is addressed.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
backend, hpc
Issue type
Documentation
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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