From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6CD355CDE6; Tue, 20 Feb 2024 08:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708418093; cv=none; b=AQS3M2/XfQUyXKMQ4UUYhhQrSLaPCByQ6LkzzCkjFBaHMV0M/zWXpxC/W4EyT99He4uAPWs2dUw9r+nwWte4u8LMw458E3wYyNH2qSmyrz7R6cQBdKntrTrGxm5+6vE1rKO0tIQ7kgS/jxXwTi5ynUYwjgcMiqFSM5Twge4lQWU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708418093; c=relaxed/simple; bh=ekyugrnvGjdr5kW4xHy9sxtpj+T8GN9Tmf1QbVkJvwI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=V7d/OrWGoE5CVD8GgU7LLAAIjdXUf0FqkhltKDbwWoOeaSCmHWdjPGCzU1QRn0sUsomGgDzQiGyr0E+dwKU2OZxJId95RRoxtUKo4+c4vPHs2GQ2NW7X0dg7eY4k/7nhl7JsNFiWa0pxl4wiHQC5ZCHdqSTGerSATLtB8LaXjCs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ubspOjZb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ubspOjZb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59755C433F1; Tue, 20 Feb 2024 08:34:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708418093; bh=ekyugrnvGjdr5kW4xHy9sxtpj+T8GN9Tmf1QbVkJvwI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ubspOjZbQnGu1lgLvawYR/iL/NjCHWmfEW62LVEyZEScQwgnVdB3ujquhJpEnqmMF 96UBa3qT+dunw7GfoSnrQDjL7mmGVrX739w/XLJYy92L7ku3rrCzBlGDsiAJpa6bE0 v6O1akrG6y8phga0urA7FNb0Dm8yIdLONWl7kz9PlUd4uR4g3HhgxpmcADzRRlkEos ub1sglxL6z/Ulns06k9GVezdcp7PUNTUdKRGatdf2l7jFYjGKcDwoTZ49KHBdlDkY9 91nxDCvzphzI70JOF0kgQMm1gm5ApdmbgzxgbZaiwz0c4aq9VIS9xeCjMVs1AbINqT umyw+02eH/5tQ== Date: Tue, 20 Feb 2024 09:34:49 +0100 From: Christian Brauner To: Oleg Nesterov Cc: Andy Lutomirski , "Eric W. Biederman" , Tycho Andersen , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] pidfd: change pidfd_send_signal() to respect PIDFD_THREAD Message-ID: <20240220-einwurf-depesche-d8682be0370c@brauner> References: <20240210123033.GA27557@redhat.com> <20240210-dackel-getan-619c70fefa62@brauner> <20240210131518.GC27557@redhat.com> <20240210-chihuahua-hinzog-3945b6abd44a@brauner> <20240210165133.GD27557@redhat.com> <20240214123655.GB16265@redhat.com> <20240216-albern-aufwiegen-1de327c7dafd@brauner> <20240216130625.GA8723@redhat.com> <20240216-ohnedies-improvisieren-58edcc102b6a@brauner> <20240216181214.GA10393@redhat.com> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240216181214.GA10393@redhat.com> On Fri, Feb 16, 2024 at 07:12:14PM +0100, Oleg Nesterov wrote: > On 02/16, Christian Brauner wrote: > > > > > SI_USER means that the target can trust the values of si_pid/si_uid > > > in siginfo. > > > > Bah, what an annoying nonsense. I see that this can be used to emulate > > stuff like SI_TIMER and SI_ASYNCIO. But I very much doubt the value of > > e.g., emulating SI_DETHREAD. Maybe I'm missing something very obvious. > > I don't understand... My question was what the purpose of being able to to set si_code to e.g., SI_DETHREAD is and then to send a signal to yourself? Because it looks like that's what rt_{tg}sigqueueinfo() and pidfd_send_signal() allows the caller to do. I'm just trying to understand use-cases for this.