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Darwish" Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , "Sebastian A. Siewior" , "Paul E. McKenney" , Steven Rostedt , LKML Subject: Re: [PATCH v1 4/5] seqlock: seqcount_LOCKTYPE_t: Introduce PREEMPT_RT support Message-ID: <20200828085938.GS1362448@hirez.programming.kicks-ass.net> References: <20200519214547.352050-1-a.darwish@linutronix.de> <20200828010710.5407-1-a.darwish@linutronix.de> <20200828010710.5407-5-a.darwish@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200828010710.5407-5-a.darwish@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 28, 2020 at 03:07:09AM +0200, Ahmed S. Darwish wrote: > +#define __SEQ_RT IS_ENABLED(CONFIG_PREEMPT_RT) > + > +SEQCOUNT_LOCKTYPE(raw_spinlock, raw_spinlock_t, false, s->lock, raw_spin, raw_spin_lock(s->lock)) > +SEQCOUNT_LOCKTYPE(spinlock, spinlock_t, __SEQ_RT, s->lock, spin, spin_lock(s->lock)) > +SEQCOUNT_LOCKTYPE(rwlock, rwlock_t, __SEQ_RT, s->lock, read, read_lock(s->lock)) > +SEQCOUNT_LOCKTYPE(mutex, struct mutex, true, s->lock, mutex, mutex_lock(s->lock)) > +SEQCOUNT_LOCKTYPE(ww_mutex, struct ww_mutex, true, &s->lock->base, ww_mutex, ww_mutex_lock(s->lock, NULL)) Ooh, reading is hard, but ^^^^ you already have that. > +/* > + * Automatically disable preemption for seqcount_LOCKTYPE_t writers, if the > + * associated lock does not implicitly disable preemption. > + * > + * Don't do it for PREEMPT_RT. Check __SEQ_LOCK(). > + */ > +#define __seq_enforce_preemption_protection(s) \ > + (!IS_ENABLED(CONFIG_PREEMPT_RT) && __seqcount_lock_preemptible(s)) Then what is this doing ?!? I'm confused now.