Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <87blobnq02.fsf@x220.int.ebiederm.org> <CAHk-=wgYCUbEmwieOBzVNZbSAM9wCZA8Z0665onpNnEcC-UpDg@mail.gmail.com>
 <AM6PR03MB5170B606F9AC663225EC9609E4C60@AM6PR03MB5170.eurprd03.prod.outlook.com>
 <CAHk-=whM3r7zrm8mSi7HJhuZbYiXx9PFU5VQYeKm6Low=r15eQ@mail.gmail.com>
 <AM6PR03MB517003D5965F48AC5FE7283DE4C60@AM6PR03MB5170.eurprd03.prod.outlook.com>
 <CAHk-=wg5LvjumW9PVQiF7jB8yig98K8XTk4tHo9W-sYmxzW+9g@mail.gmail.com>
 <87lfnda3w3.fsf@x220.int.ebiederm.org> <CAHk-=wjxyGCj9675mf31uhoJCyHn74ON_+O6SjSqBSSvqWxC1Q@mail.gmail.com>
 <328f5ad3-f8b3-09b9-f2f7-b6dae0137542@redhat.com>
In-Reply-To: <328f5ad3-f8b3-09b9-f2f7-b6dae0137542@redhat.com>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 3 Apr 2020 13:59:08 -0700
Message-ID: <CAHk-=wgww8LFqUenUtNV7hzYSxAemjbOVYfZMXqOxK7DGRrZaw@mail.gmail.com>
Subject: Re: [GIT PULL] Please pull proc and exec work for 5.7-rc1
To:     Waiman Long <longman@redhat.com>
Cc:     "Eric W. Biederman" <ebiederm@xmission.com>,
        Ingo Molnar <mingo@kernel.org>, Will Deacon <will@kernel.org>,
        Bernd Edlinger <bernd.edlinger@hotmail.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alexey Gladkov <gladkov.alexey@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Apr 3, 2020 at 1:41 PM Waiman Long <longman@redhat.com> wrote:
>
> Another alternative is to add new functions like down_read_unfair() that
> perform unfair read locking for its callers. That will require less code
> change, but the calling functions have to make the right choice.

I'd prefer the static choice model - and I'd hide this in some
"task_cred_read_lock()" function anyway rather than have the users do
"mutex_lock_killable(&task->signal->cred_guard_mutex)" like they do
now.

How nasty would it be to add the "upgrade" op? I took a quick look,
but that just made me go "Waiman would know" ;)

             Linus