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* [PATCH] PCI: Remove WARN_ON(in_interrupt()).
@ 2021-02-08 19:44 Sebastian Andrzej Siewior
  2021-02-10 23:01 ` Bjorn Helgaas
  0 siblings, 1 reply; 2+ messages in thread
From: Sebastian Andrzej Siewior @ 2021-02-08 19:44 UTC (permalink / raw)
  To: linux-pci; +Cc: Bjorn Helgaas, Thomas Gleixner, Sebastian Andrzej Siewior

WARN_ON(in_interrupt()) is used for historic reasons to ensure proper
usage of down_read() and predates might_sleep() and lockdep.

down_read() has might_sleep() which also catches users from preemption
disabled regions while in_interrupt() does not.

Remove WARN_ON(in_interrupt()) because there is better debugging
facility.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/pci/search.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 2061672954ee3..b4c138a6ec025 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -168,7 +168,6 @@ struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
 	struct list_head *n;
 	struct pci_bus *b = NULL;
 
-	WARN_ON(in_interrupt());
 	down_read(&pci_bus_sem);
 	n = from ? from->node.next : pci_root_buses.next;
 	if (n != &pci_root_buses)
@@ -196,7 +195,6 @@ struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn)
 {
 	struct pci_dev *dev;
 
-	WARN_ON(in_interrupt());
 	down_read(&pci_bus_sem);
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
@@ -274,7 +272,6 @@ static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
 	struct device *dev_start = NULL;
 	struct pci_dev *pdev = NULL;
 
-	WARN_ON(in_interrupt());
 	if (from)
 		dev_start = &from->dev;
 	dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
@@ -381,7 +378,6 @@ int pci_dev_present(const struct pci_device_id *ids)
 {
 	struct pci_dev *found = NULL;
 
-	WARN_ON(in_interrupt());
 	while (ids->vendor || ids->subvendor || ids->class_mask) {
 		found = pci_get_dev_by_id(ids, NULL);
 		if (found) {
-- 
2.30.0


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] PCI: Remove WARN_ON(in_interrupt()).
  2021-02-08 19:44 [PATCH] PCI: Remove WARN_ON(in_interrupt()) Sebastian Andrzej Siewior
@ 2021-02-10 23:01 ` Bjorn Helgaas
  0 siblings, 0 replies; 2+ messages in thread
From: Bjorn Helgaas @ 2021-02-10 23:01 UTC (permalink / raw)
  To: Sebastian Andrzej Siewior; +Cc: linux-pci, Bjorn Helgaas, Thomas Gleixner

On Mon, Feb 08, 2021 at 08:44:00PM +0100, Sebastian Andrzej Siewior wrote:
> WARN_ON(in_interrupt()) is used for historic reasons to ensure proper
> usage of down_read() and predates might_sleep() and lockdep.
> 
> down_read() has might_sleep() which also catches users from preemption
> disabled regions while in_interrupt() does not.
> 
> Remove WARN_ON(in_interrupt()) because there is better debugging
> facility.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Applied to pci/misc for v5.12, thanks!

> ---
>  drivers/pci/search.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> index 2061672954ee3..b4c138a6ec025 100644
> --- a/drivers/pci/search.c
> +++ b/drivers/pci/search.c
> @@ -168,7 +168,6 @@ struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
>  	struct list_head *n;
>  	struct pci_bus *b = NULL;
>  
> -	WARN_ON(in_interrupt());
>  	down_read(&pci_bus_sem);
>  	n = from ? from->node.next : pci_root_buses.next;
>  	if (n != &pci_root_buses)
> @@ -196,7 +195,6 @@ struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn)
>  {
>  	struct pci_dev *dev;
>  
> -	WARN_ON(in_interrupt());
>  	down_read(&pci_bus_sem);
>  
>  	list_for_each_entry(dev, &bus->devices, bus_list) {
> @@ -274,7 +272,6 @@ static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
>  	struct device *dev_start = NULL;
>  	struct pci_dev *pdev = NULL;
>  
> -	WARN_ON(in_interrupt());
>  	if (from)
>  		dev_start = &from->dev;
>  	dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
> @@ -381,7 +378,6 @@ int pci_dev_present(const struct pci_device_id *ids)
>  {
>  	struct pci_dev *found = NULL;
>  
> -	WARN_ON(in_interrupt());
>  	while (ids->vendor || ids->subvendor || ids->class_mask) {
>  		found = pci_get_dev_by_id(ids, NULL);
>  		if (found) {
> -- 
> 2.30.0
> 

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2021-02-08 19:44 [PATCH] PCI: Remove WARN_ON(in_interrupt()) Sebastian Andrzej Siewior
2021-02-10 23:01 ` Bjorn Helgaas

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