[PATCH v2] cxl: Prevent IRQ storm

[PATCH v2] cxl: Prevent IRQ storm

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In some situations, a faulty AFU slice may create an interrupt storm,
rendering the machine unusable. Since these interrupts are informational
only, present the interrupt once, then mask it off to prevent it from
being retriggered until the card is reset.

Changelog:
v2
	Rebase against linux-next

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/cxl/native.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 194c58e..95a776a 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -1205,7 +1205,7 @@ static irqreturn_t native_slice_irq_err(int irq, void *data)
 {
 	struct cxl_afu *afu = data;
 	u64 errstat, serr, afu_error, dsisr;
-	u64 fir_slice, afu_debug;
+	u64 fir_slice, afu_debug, irq_mask;
 
 	/*
 	 * slice err interrupt is only used with full PSL (no XSL)
@@ -1226,6 +1226,10 @@ static irqreturn_t native_slice_irq_err(int irq, void *data)
 	dev_crit(&afu->dev, "AFU_ERR_An: 0x%.16llx\n", afu_error);
 	dev_crit(&afu->dev, "PSL_DSISR_An: 0x%.16llx\n", dsisr);
 
+	/* mask off the IRQ so it won't retrigger until the card is reset */
+	irq_mask = (serr & 0xff80000000000000ULL) >> 32;
+	serr |= irq_mask;
+
 	cxl_p1n_write(afu, CXL_PSL_SERR_An, serr);
 
 	return IRQ_HANDLED;
-- 
2.9.3

Re: [PATCH v2] cxl: Prevent IRQ storm

[Andrew Donnellan]

On 27/04/17 11:37, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
>
> In some situations, a faulty AFU slice may create an interrupt storm,
> rendering the machine unusable. Since these interrupts are informational
> only, present the interrupt once, then mask it off to prevent it from
> being retriggered until the card is reset.
>
> Changelog:
> v2
> 	Rebase against linux-next

The patch changelog shouldn't be part of the commit message - it should 
go under a "---" line after the sign-off so it doesn't get included in 
the final commit.

Also now that I've taken a second look, I think the summary line of the 
commit message could be more descriptive, something like:

"cxl: mask slice error interrupt after first occurrence"

or something to that effect?


Andrew

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2] cxl: Prevent IRQ storm

[Alastair D'Silva]

On Thu, 2017-04-27 at 14:41 +1000, Andrew Donnellan wrote:
On 27/04/17 11:37, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > In some situations, a faulty AFU slice may create an interrupt
> > storm,
> > rendering the machine unusable. Since these interrupts are
> > informational
> > only, present the interrupt once, then mask it off to prevent it
> > from
> > being retriggered until the card is reset.
> > 
> > Changelog:
> > v2
> > 	Rebase against linux-next
> 
> The patch changelog shouldn't be part of the commit message - it
> should 
> go under a "---" line after the sign-off so it doesn't get included
> in 
> the final commit.
> 
> Also now that I've taken a second look, I think the summary line of
> the 
> commit message could be more descriptive, something like:
> 
> "cxl: mask slice error interrupt after first occurrence"
> 
> or something to that effect?
> 

Ok

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

Re: [PATCH v2] cxl: Prevent IRQ storm

[Michael Ellerman]

Andrew Donnellan <andrew.donnellan@au1.ibm.com> writes:

> On 27/04/17 11:37, Alastair D'Silva wrote:
>> From: Alastair D'Silva <alastair@d-silva.org>
>>
>> In some situations, a faulty AFU slice may create an interrupt storm,
>> rendering the machine unusable. Since these interrupts are informational
>> only, present the interrupt once, then mask it off to prevent it from
>> being retriggered until the card is reset.
>>
>> Changelog:
>> v2
>> 	Rebase against linux-next
>
> The patch changelog shouldn't be part of the commit message - it should 
> go under a "---" line after the sign-off so it doesn't get included in 
> the final commit.
>
> Also now that I've taken a second look, I think the summary line of the 
> commit message could be more descriptive, something like:
>
> "cxl: mask slice error interrupt after first occurrence"
        ^
        M

:D

cheers