linux-kernel - [PATCH v2] x86: UV uv_flush_tlb_others WARN

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Message-Id: <E1LfjVI-0006v9-MG@eag09.americas.sgi.com>
Date:	Fri, 06 Mar 2009 17:30:56 -0600
From:	Cliff Wickman <cpw@....com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, tj@...nel.org
Subject: [PATCH v2] x86: UV uv_flush_tlb_others WARN_ON



From: Cliff Wickman <cpw@....com>

The problem WARN_ON remains in Ingo's tree, and linux-next.
It should be dropped.

uv_flush_tlb_others() (arch/x86/kernel/tlb_uv.c)
The "WARN_ON(!in_atomic())" fails if CONFIG_PREEMPT is not enabled.
And CONFIG_PREEMPT is not enabled by default in the distribution that
most UV owners will use.

We could #ifdef CONFIG_PREEMPT the warning, but that is not good form.
And there seems to be no suitable fix to in_atomic() when CONFIG_PREMPT
is not on.
  As you commented, Ingo:
  > and we have no proper primitive to test for atomicity. (mainly
  > because we dont know about atomicity on a non-preempt kernel)

I propose that we drop the WARN_ON.

Diffed against 2.6.29-rc2

Signed-off-by: Cliff Wickman <cpw@....com>
---
 arch/x86/kernel/tlb_uv.c |    2 --
 1 file changed, 2 deletions(-)

Index: linux/arch/x86/kernel/tlb_uv.c
===================================================================
--- linux.orig/arch/x86/kernel/tlb_uv.c
+++ linux/arch/x86/kernel/tlb_uv.c
@@ -316,8 +316,6 @@ const struct cpumask *uv_flush_tlb_other
 	int locals = 0;
 	struct bau_desc *bau_desc;
 
-	WARN_ON(!in_atomic());
-
 	cpumask_andnot(flush_mask, cpumask, cpumask_of(cpu));
 
 	uv_cpu = uv_blade_processor_id();
--
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