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Re: [PATCH v8 08/20] blockjob.h: introduce block_job _locked() APIs
From: |
Emanuele Giuseppe Esposito |
Subject: |
Re: [PATCH v8 08/20] blockjob.h: introduce block_job _locked() APIs |
Date: |
Tue, 5 Jul 2022 10:12:10 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 |
Am 05/07/2022 um 09:58 schrieb Stefan Hajnoczi:
> On Wed, Jun 29, 2022 at 10:15:26AM -0400, Emanuele Giuseppe Esposito wrote:
>> +BlockJob *block_job_next(BlockJob *bjob)
>> {
>> - Job *job = job_get(id);
>> + JOB_LOCK_GUARD();
>> + return block_job_next_locked(bjob);
>> +}
>
> This seems unsafe for the same reason as job_ref(). How can the caller
> be sure bjob is still valid if it doesn't hold the mutex and has no
> reference to it?
>
> Maybe the assumption is that the next()/get()/unref() APIs are
> GLOBAL_STATE_CODE(), so there can be no race between them?
>
Same answer as job_ref. Unfortunately if we want to keep this logic in
this serie that's the price to pay (even though it's just till patch 13).
No assumption I would say.
Emanuele