[PATCH v2] x86: UV uv_flush_tlb_others WARN_ON

[PATCH v2] x86: UV uv_flush_tlb_others WARN_ON

[Cliff Wickman]

From: Cliff Wickman <cpw@sgi.com>

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@sgi.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();

Re: [PATCH v2] x86: UV uv_flush_tlb_others WARN_ON

[Tejun Heo]

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

Heh.. I included it in the first two merges but forgot it in the final
round.  Applying to tj-percpu.

Thanks.

-- 
tejun

[PATCH v2] x86: UV uv_flush_tlb_others WARN_ON

[Cliff Wickman]

From: Cliff Wickman <cpw@sgi.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@sgi.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();

Re: [PATCH v2] x86: UV uv_flush_tlb_others WARN_ON

[Tejun Heo]

Cliff Wickman wrote:
> From: Cliff Wickman <cpw@sgi.com>
> 
> The problem WARN_ON remains in Ingo's tree, and linux-next.
> It should be dropped.

Sorry, I must have lost it while tinkering with branches.  Added to
#tj-percpu.  Ingo, the patch is on top of the locking granuality
patchset.  Pulling #tj-percpu will include this one too.

Thanks.

-- 
tejun