From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Colascione Subject: Re: [RFC PATCH for 4.18 00/14] Restartable Sequences Date: Thu, 03 May 2018 16:22:00 +0000 Message-ID: References: <20180430224433.17407-1-mathieu.desnoyers@efficios.com> <660904075.9201.1525276988842.JavaMail.zimbra@efficios.com> <1718748931.10084.1525363941807.JavaMail.zimbra@efficios.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <1718748931.10084.1525363941807.JavaMail.zimbra@efficios.com> Sender: linux-kernel-owner@vger.kernel.org To: Mathieu Desnoyers Cc: Peter Zijlstra , Paul McKenney , boqun.feng@gmail.com, luto@amacapital.net, davejwatson@fb.com, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Paul Turner , Andrew Morton , linux@arm.linux.org.uk, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, Andrew Hunter , andi@firstfloor.org, cl@linux.com, bmaurer@fb.com, rostedt@goodmis.org, josh@joshtriplett.org, torvalds@linux-foundation.org, catalin.marinas@arm.com, will.deacon@arm.com, Michael Kerrisk-manpages , Joel Fernandes List-Id: linux-api@vger.kernel.org On Thu, May 3, 2018 at 9:12 AM Mathieu Desnoyers < mathieu.desnoyers@efficios.com> wrote: > By the way, if we eventually find a way to enhance user-space mutexes in the > fashion you describe here, it would belong to another TLS area, and would > be registered by another system call than rseq. I proposed a more generic > "TLS area registration" system call a few years ago, but Linus told me he > wanted a system call that was specific to rseq. If we need to implement > other use-cases in a TLS area shared between kernel and user-space in a > similar fashion, the plan is to do it in a distinct system call. If we proliferate TLS areas; we'd have to register each one upon thread creation, adding to the overall thread creation path. There's already a provision for versioning the TLS area. What's the benefit of splitting the registration over multiple system calls?