linux-kernel - [PATCH RT] Revert "cpumask: Disable CONFIG_CPUMASK

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Date:   Wed, 18 Dec 2019 18:41:59 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     linux-rt-users <linux-rt-users@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH RT] Revert "cpumask: Disable CONFIG_CPUMASK_OFFSTACK for RT"

The one x86 case we had was fixed in commit
	832df3d47badc ("x86/smp: Enhance native_send_call_func_ipi()")

I didn't find another in-IRQ user. Most callers use GFP_KERNEL and the
ATOMIC users are allocating the mask while holding a spinlock_t.

Allow to use CPUMASK_OFFSTACK becauase it no longer is a problem on RT.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 arch/x86/Kconfig | 2 +-
 lib/Kconfig      | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7f359aacf8148..4b77b3273051e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -967,7 +967,7 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT
 config MAXSMP
 	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
 	depends on X86_64 && SMP && DEBUG_KERNEL
-	select CPUMASK_OFFSTACK if !PREEMPT_RT
+	select CPUMASK_OFFSTACK
 	---help---
 	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
 	  If unsure, say N.
diff --git a/lib/Kconfig b/lib/Kconfig
index 298b41298e487..3321d04dfa5a5 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -468,7 +468,6 @@ config CHECK_SIGNATURE
 
 config CPUMASK_OFFSTACK
 	bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
-	depends on !PREEMPT_RT
 	help
 	  Use dynamic allocation for cpumask_var_t, instead of putting
 	  them on the stack.  This is a bit more expensive, but avoids
-- 
2.24.0