ahci: Do not receive interrupts sent by dummy ports

PATCH In review Alexander Gordeev 3 participants 5 messages Apr 17, 2014 – Apr 18, 2014 libata

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Alexander Gordeev

author

2014-04-17 17:04 UTC #0 lore raw

cover ahci: Do not receive interrupts sent by dummy ports

Tejun, David,

I would expect handle_bad_irq()->print_irq_desc() gets called if dummy port interrupt arrived. Could be a spurious interrupt complain as well.

Cc Tejun Heo <[email protected]>

Cc David Milburn <[email protected]>

Cc [email protected]

Alexander Gordeev (1):
ahci: Do not receive interrupts sent by dummy ports

 drivers/ata/ahci.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

Signature · 1 line

1.7.7.6

Alexander Gordeev

author

2014-04-17 17:04 UTC #1 lore raw

PATCH 1/1 ahci: Do not receive interrupts sent by dummy ports

In multiple MSI mode all AHCI ports (including dummy) get assigned separate MSI vectors and (as result of execution pci_enable_msi_exact() function) separate IRQ numbers, (mapped to the MSI vectors).

Therefore, although interrupts from dummy ports are not desired they are still enabled. We do not request IRQs for dummy ports, but that only means we do not assign AHCI-specific ISRs to corresponding IRQ numbers.

As result, dummy port interrupts still could come and traverse all the way from the PCI device to the kernel, causing unnecessary overhead.

This update disables IRQs for dummy ports and prevents the described issue.

Signed-off-by Alexander Gordeev <[email protected]>

Cc Tejun Heo <[email protected]>

Cc David Milburn <[email protected]>

Cc [email protected]

---
 drivers/ata/ahci.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

drivers/ata/ahci.c +10 -6

index 44d40c7..71e15b7 100644
@@ -1241,12 +1241,16 @@ int ahci_host_activate(struct ata_host *host, int irq, unsigned int n_msis)
 	for (i = 0; i < host->n_ports; i++) {
 		struct ahci_port_priv *pp = host->ports[i]->private_data;
 
-		/* pp is NULL for dummy ports */
-		if (pp)
-			rc = devm_request_threaded_irq(host->dev,
-						       irq + i, ahci_hw_interrupt,
-						       ahci_thread_fn, IRQF_SHARED,
-						       pp->irq_desc, host->ports[i]);
+		/* Do not receive interrupts sent by dummy ports */
+		if (!pp) {
+			disable_irq(irq + i);
+			continue;
+		}
+
+		rc = devm_request_threaded_irq(host->dev, irq + i,
+					       ahci_hw_interrupt,
+					       ahci_thread_fn, IRQF_SHARED,
+					       pp->irq_desc, host->ports[i]);
 		if (rc)
 			goto out_free_irqs;
 	}

Signature · 1 line

1.7.7.6

Tejun Heo

2014-04-17 17:06 UTC #2 lore raw

Quoted 14 lines · Alexander Gordeev

In multiple MSI mode all AHCI ports (including dummy) get assigned separate MSI vectors and (as result of execution pci_enable_msi_exact() function) separate IRQ numbers, (mapped to the MSI vectors).
Therefore, although interrupts from dummy ports are not desired they are still enabled. We do not request IRQs for dummy ports, but that only means we do not assign AHCI-specific ISRs to corresponding IRQ numbers.
As result, dummy port interrupts still could come and traverse all the way from the PCI device to the kernel, causing unnecessary overhead.

Quoted 7 lines

This update disables IRQs for dummy ports and prevents the described issue.
Signed-off-by Alexander Gordeev <[email protected]>
Cc Tejun Heo <[email protected]>
Cc David Milburn <[email protected]>
Cc [email protected]

David, can you please test the patch?

Thanks.

Signature · 1 line

tejun

David Milburn

2014-04-17 17:51 UTC #3 lore raw

Quoted 18 lines · Tejun Heo

Quoted 17 lines · Alexander Gordeev
In multiple MSI mode all AHCI ports (including dummy) get assigned separate MSI vectors and (as result of execution pci_enable_msi_exact() function) separate IRQ numbers, (mapped to the MSI vectors).
Therefore, although interrupts from dummy ports are not desired they are still enabled. We do not request IRQs for dummy ports, but that only means we do not assign AHCI-specific ISRs to corresponding IRQ numbers.
As result, dummy port interrupts still could come and traverse all the way from the PCI device to the kernel, causing unnecessary overhead.
This update disables IRQs for dummy ports and prevents the described issue.

Quoted 7 lines

Quoted 4 lines
Signed-off-by Alexander Gordeev <[email protected]>
Cc Tejun Heo <[email protected]>
Cc David Milburn <[email protected]>
Cc [email protected]
David, can you please test the patch?

Hi,

I have re-tested successfully, this patch prevents the crash when using kdump, and I boot tested a system that boots off ahci and has dummy ports present, no problems seen.

Thanks,
David

Tejun Heo

2014-04-18 19:56 UTC #4 lore raw

In reply to Alexander Gordeev

Quoted 14 lines · Alexander Gordeev

In multiple MSI mode all AHCI ports (including dummy) get assigned separate MSI vectors and (as result of execution pci_enable_msi_exact() function) separate IRQ numbers, (mapped to the MSI vectors).
Therefore, although interrupts from dummy ports are not desired they are still enabled. We do not request IRQs for dummy ports, but that only means we do not assign AHCI-specific ISRs to corresponding IRQ numbers.
As result, dummy port interrupts still could come and traverse all the way from the PCI device to the kernel, causing unnecessary overhead.

Quoted 7 lines

This update disables IRQs for dummy ports and prevents the described issue.
Signed-off-by Alexander Gordeev <[email protected]>
Cc Tejun Heo <[email protected]>
Cc David Milburn <[email protected]>
Cc [email protected]

Applied to libata/for-3.15-fixes w/ David's tested-by added.

Thanks.

Signature · 1 line

tejun