Message-ID: <3302e349-c2c5-d116-960d-3c0c4e713227@oracle.com>
Date:   Sun, 5 Feb 2023 10:06:04 -0600
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Subject: Re: [PATCH v11 4/8] fork: Add USER_WORKER flag to ignore signals
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     hch@infradead.org, stefanha@redhat.com, jasowang@redhat.com,
        mst@redhat.com, sgarzare@redhat.com,
        virtualization@lists.linux-foundation.org, brauner@kernel.org,
        ebiederm@xmission.com, konrad.wilk@oracle.com,
        linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
References: <20230202232517.8695-1-michael.christie@oracle.com>
 <20230202232517.8695-5-michael.christie@oracle.com>
 <CAHk-=wjF6j264jDFcY3wgzOUA2RL2SpD2oL5BF9JqCkz3A413Q@mail.gmail.com>
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From:   Mike Christie <michael.christie@oracle.com>
In-Reply-To: <CAHk-=wjF6j264jDFcY3wgzOUA2RL2SpD2oL5BF9JqCkz3A413Q@mail.gmail.com>
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On 2/2/23 6:19 PM, Linus Torvalds wrote:
> On Thu, Feb 2, 2023 at 3:25 PM Mike Christie
> <michael.christie@oracle.com> wrote:
>>
>> +       if (args->worker_flags & USER_WORKER_SIG_IGN)
>> +               ignore_signals(p);
> 
> Same comment as for the other case.
> 
> There are real reasons to avoid bitfields:
> 
>  - you can't pass addresses to them around
> 
>  - it's easier to read or assign multiple fields in one go
> 
>  - they are horrible for ABI issues due to the exact bit ordering and
> padding being very subtle
> 
> but none of those issues are relevant here, where it's a kernel-internal ABI.
> 
> All these use-cases seem to actually be testing one bit at a time, and
> the "assignments" are structure initializers for which named bitfields
> are actually perfect and just make the initializer more legible.
> 

Thanks for the comments. I see what you mean and have fixed those instances and
updated kthread as well.