Commit 8f62819a authored by Bartosz Golaszewski's avatar Bartosz Golaszewski Committed by Bjorn Helgaas
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PCI/pwrctl: Rescan bus on a separate thread 

If we trigger the bus rescan from sysfs, we'll try to lock the PCI rescan
mutex recursively and deadlock - the platform device will be populated and
probed on the same thread that handles the sysfs write.

Add a workqueue to the pwrctl code on which we schedule the rescan for
controlled PCI devices. While at it: add a new interface for initializing
the pwrctl context where we'd now assign the parent device address and
initialize the workqueue.

Link: https://lore.kernel.org/r/20240823093323.33450-3-brgl@bgdev.pl


Fixes: 4565d265 ("PCI/pwrctl: Add PCI power control core code")
Reported-by: default avatarKonrad Dybcio <konradybcio@kernel.org>
Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
parent f1536585

drivers/pci/pwrctl/core.c

+23 −3
Original line number Diff line number Diff line
@@ -48,6 +48,28 @@ static int pci_pwrctl_notify(struct notifier_block *nb, unsigned long action, 
	return NOTIFY_DONE;

}



static void rescan_work_func(struct work_struct *work)

{

	struct pci_pwrctl *pwrctl = container_of(work, struct pci_pwrctl, work);



	pci_lock_rescan_remove();

	pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus);

	pci_unlock_rescan_remove();

}



/**

 * pci_pwrctl_init() - Initialize the PCI power control context struct

 *

 * @pwrctl: PCI power control data

 * @dev: Parent device

 */

void pci_pwrctl_init(struct pci_pwrctl *pwrctl, struct device *dev)

{

	pwrctl->dev = dev;

	INIT_WORK(&pwrctl->work, rescan_work_func);

}

EXPORT_SYMBOL_GPL(pci_pwrctl_init);



/**

 * pci_pwrctl_device_set_ready() - Notify the pwrctl subsystem that the PCI

 * device is powered-up and ready to be detected.
@@ -74,9 +96,7 @@ int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl) 
	if (ret)

		return ret;



	pci_lock_rescan_remove();

	pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus);

	pci_unlock_rescan_remove();

	schedule_work(&pwrctl->work);



	return 0;

}

drivers/pci/pwrctl/pci-pwrctl-pwrseq.c

+1 −1
Original line number Diff line number Diff line
@@ -50,7 +50,7 @@ static int pci_pwrctl_pwrseq_probe(struct platform_device *pdev) 
	if (ret)

		return ret;



	data->ctx.dev = dev;

	pci_pwrctl_init(&data->ctx, dev);



	ret = devm_pci_pwrctl_device_set_ready(dev, &data->ctx);

	if (ret)

include/linux/pci-pwrctl.h

+3 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#define __PCI_PWRCTL_H__



#include <linux/notifier.h>

#include <linux/workqueue.h>



struct device;

struct device_link;
@@ -41,8 +42,10 @@ struct pci_pwrctl { 
	/* Private: don't use. */

	struct notifier_block nb;

	struct device_link *link;

	struct work_struct work;

};



void pci_pwrctl_init(struct pci_pwrctl *pwrctl, struct device *dev);

int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl);

void pci_pwrctl_device_unset_ready(struct pci_pwrctl *pwrctl);

int devm_pci_pwrctl_device_set_ready(struct device *dev,