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Date:   Tue, 7 Jan 2020 21:54:50 +0100
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Sargun Dhillon <sargun@sargun.me>
Cc:     linux-kernel@vger.kernel.org,
        containers@lists.linux-foundation.org, linux-api@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, tycho@tycho.ws, jannh@google.com,
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        viro@zeniv.linux.org.uk, gpascutto@mozilla.com,
        ealvarez@mozilla.com, fweimer@redhat.com, jld@mozilla.com,
        arnd@arndb.de
Subject: Re: [PATCH v9 0/4] Add pidfd_getfd syscall
Message-ID: <20200107205449.5dcp7o3hplg7r3fw@wittgenstein>
References: <20200107175927.4558-1-sargun@sargun.me>
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On Tue, Jan 07, 2020 at 09:59:23AM -0800, Sargun Dhillon wrote:
> This patchset introduces a mechanism (pidfd_getfd syscall) to get file
> descriptors from other processes via pidfd. Although this can be achieved
> using SCM_RIGHTS, and parasitic code injection, this offers a more
> straightforward mechanism, with less overhead and complexity. The process
> under manipulation's fd still remains valid, and unmodified by the
> copy operation.
> 
> It introduces a flags field. The flags field is reserved a the moment,
> but the intent is to extend it with the following capabilities:
>  * Close the remote FD when copying it
>  * Drop the cgroup data if it's a fd pointing a socket when copying it
> 
> The syscall numbers were chosen to be one greater than openat2.
> 
> Summary of history:
> This initially started as a ptrace command. It did not require the process
> to be stopped, and felt like kind of an awkward fit for ptrace. After that,
> it moved to an ioctl on the pidfd. Given the core functionality, it made
> sense to make it a syscall which did not require the process to be stopped.
> 
> Previous versions:
>  V8: https://lore.kernel.org/lkml/20200103162928.5271-1-sargun@sargun.me/
>  V7: https://lore.kernel.org/lkml/20191226180227.GA29389@ircssh-2.c.rugged-nimbus-611.internal/
>  V6: https://lore.kernel.org/lkml/20191223210823.GA25083@ircssh-2.c.rugged-nimbus-611.internal/
>  V5: https://lore.kernel.org/lkml/20191220232746.GA20215@ircssh-2.c.rugged-nimbus-611.internal/
>  V4: https://lore.kernel.org/lkml/20191218235310.GA17259@ircssh-2.c.rugged-nimbus-611.internal/
>  V3: https://lore.kernel.org/lkml/20191217005842.GA14379@ircssh-2.c.rugged-nimbus-611.internal/
>  V2: https://lore.kernel.org/lkml/20191209070446.GA32336@ircssh-2.c.rugged-nimbus-611.internal/
>  RFC V1: https://lore.kernel.org/lkml/20191205234450.GA26369@ircssh-2.c.rugged-nimbus-611.internal/

I don't see anything wrong with this series anymore:

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

Other Acked-bys/Reviewed-bys and reviews of course strongly encouraged!
Christian