Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 20 Oct 2020 13:30:09 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     Christian Eggers <ceggers@arri.de>, tglx@linutronix.de,
        linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: sched: system doesn't boot since  "sched: Add new
 migrate_disable() implementation"
Message-ID: <20201020113009.GR2628@hirez.programming.kicks-ass.net>
References: <1654655.1jrfHnk7pZ@n95hx1g2>
 <20201019150935.koqbk57dmahhomdc@linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20201019150935.koqbk57dmahhomdc@linutronix.de>
Precedence: bulk

On Mon, Oct 19, 2020 at 05:09:35PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-10-19 12:21:06 [+0200], Christian Eggers wrote:
> > I have problems with the latest 5.9-rt releases on i.MX6ULL (!CONFIG_SMP):
> > 
> …
> > Any hints?
> 
> Thank you for the report. The reason is the migrate_disable()
> implementation for !SMP.

This should fix things I suppose. I'll fold it in.

---
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -378,7 +378,12 @@ static inline void preempt_notifier_init
 extern void migrate_disable(void);
 extern void migrate_enable(void);
 
-#else /* !(CONFIG_SMP && CONFIG_PREEMPT_RT) */
+#elif defined(CONFIG_PREEMPT_RT)
+
+static inline void migrate_disable(void) { }
+static inline void migrate_enable(void { }
+
+#else /* !CONFIG_PREEMPT_RT */
 
 /**
  * migrate_disable - Prevent migration of the current task