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	genirq/msi: Simplify sysfs handling
The sysfs handling for MSI is a convoluted maze and it is in the way of
supporting dynamic expansion of the MSI-X vectors because it only supports
a one off bulk population/free of the sysfs entries.
Change it to do:
   1) Creating an empty sysfs attribute group when msi_device_data is
      allocated
   2) Populate the entries when the MSI descriptor is initialized
   3) Free the entries when a MSI descriptor is detached from a Linux
      interrupt.
   4) Provide functions for the legacy non-irqdomain fallback code to
      do a bulk population/free. This code won't support dynamic
      expansion.
This makes the code simpler and reduces the number of allocations as the
empty attribute group can be shared.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211206210749.224917330@linutronix.de
			
			
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					 2 changed files with 107 additions and 122 deletions
				
			
		|  | @ -71,7 +71,7 @@ struct irq_data; | |||
| struct msi_desc; | ||||
| struct pci_dev; | ||||
| struct platform_msi_priv_data; | ||||
| struct attribute_group; | ||||
| struct device_attribute; | ||||
| 
 | ||||
| void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg); | ||||
| #ifdef CONFIG_GENERIC_MSI_IRQ | ||||
|  | @ -129,6 +129,7 @@ struct pci_msi_desc { | |||
|  * @dev:	Pointer to the device which uses this descriptor | ||||
|  * @msg:	The last set MSI message cached for reuse | ||||
|  * @affinity:	Optional pointer to a cpu affinity mask for this descriptor | ||||
|  * @sysfs_attr:	Pointer to sysfs device attribute | ||||
|  * | ||||
|  * @write_msi_msg:	Callback that may be called when the MSI message | ||||
|  *			address or data changes | ||||
|  | @ -148,6 +149,9 @@ struct msi_desc { | |||
| #ifdef CONFIG_IRQ_MSI_IOMMU | ||||
| 	const void			*iommu_cookie; | ||||
| #endif | ||||
| #ifdef CONFIG_SYSFS | ||||
| 	struct device_attribute		*sysfs_attrs; | ||||
| #endif | ||||
| 
 | ||||
| 	void (*write_msi_msg)(struct msi_desc *entry, void *data); | ||||
| 	void *write_msi_msg_data; | ||||
|  | @ -171,7 +175,6 @@ enum msi_desc_filter { | |||
| /**
 | ||||
|  * msi_device_data - MSI per device data | ||||
|  * @properties:		MSI properties which are interesting to drivers | ||||
|  * @attrs:		Pointer to the sysfs attribute group | ||||
|  * @platform_data:	Platform-MSI specific data | ||||
|  * @list:		List of MSI descriptors associated to the device | ||||
|  * @mutex:		Mutex protecting the MSI list | ||||
|  | @ -179,7 +182,6 @@ enum msi_desc_filter { | |||
|  */ | ||||
| struct msi_device_data { | ||||
| 	unsigned long			properties; | ||||
| 	const struct attribute_group    **attrs; | ||||
| 	struct platform_msi_priv_data	*platform_data; | ||||
| 	struct list_head		list; | ||||
| 	struct mutex			mutex; | ||||
|  | @ -264,14 +266,6 @@ void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg); | |||
| void pci_msi_mask_irq(struct irq_data *data); | ||||
| void pci_msi_unmask_irq(struct irq_data *data); | ||||
| 
 | ||||
| #ifdef CONFIG_SYSFS | ||||
| int msi_device_populate_sysfs(struct device *dev); | ||||
| void msi_device_destroy_sysfs(struct device *dev); | ||||
| #else /* CONFIG_SYSFS */ | ||||
| static inline int msi_device_populate_sysfs(struct device *dev) { return 0; } | ||||
| static inline void msi_device_destroy_sysfs(struct device *dev) { } | ||||
| #endif /* !CONFIG_SYSFS */ | ||||
| 
 | ||||
| /*
 | ||||
|  * The arch hooks to setup up msi irqs. Default functions are implemented | ||||
|  * as weak symbols so that they /can/ be overriden by architecture specific | ||||
|  | @ -285,6 +279,13 @@ int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc); | |||
| void arch_teardown_msi_irq(unsigned int irq); | ||||
| int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type); | ||||
| void arch_teardown_msi_irqs(struct pci_dev *dev); | ||||
| #ifdef CONFIG_SYSFS | ||||
| int msi_device_populate_sysfs(struct device *dev); | ||||
| void msi_device_destroy_sysfs(struct device *dev); | ||||
| #else /* CONFIG_SYSFS */ | ||||
| static inline int msi_device_populate_sysfs(struct device *dev) { return 0; } | ||||
| static inline void msi_device_destroy_sysfs(struct device *dev) { } | ||||
| #endif /* !CONFIG_SYSFS */ | ||||
| #endif /* CONFIG_PCI_MSI_ARCH_FALLBACKS */ | ||||
| 
 | ||||
| /*
 | ||||
|  |  | |||
							
								
								
									
										204
									
								
								kernel/irq/msi.c
									
									
									
									
									
								
							
							
						
						
									
										204
									
								
								kernel/irq/msi.c
									
									
									
									
									
								
							|  | @ -19,6 +19,7 @@ | |||
| 
 | ||||
| #include "internals.h" | ||||
| 
 | ||||
| static inline int msi_sysfs_create_group(struct device *dev); | ||||
| #define dev_to_msi_list(dev)	(&(dev)->msi.data->list) | ||||
| 
 | ||||
| /**
 | ||||
|  | @ -178,6 +179,7 @@ static void msi_device_data_release(struct device *dev, void *res) | |||
| int msi_setup_device_data(struct device *dev) | ||||
| { | ||||
| 	struct msi_device_data *md; | ||||
| 	int ret; | ||||
| 
 | ||||
| 	if (dev->msi.data) | ||||
| 		return 0; | ||||
|  | @ -186,6 +188,12 @@ int msi_setup_device_data(struct device *dev) | |||
| 	if (!md) | ||||
| 		return -ENOMEM; | ||||
| 
 | ||||
| 	ret = msi_sysfs_create_group(dev); | ||||
| 	if (ret) { | ||||
| 		devres_free(md); | ||||
| 		return ret; | ||||
| 	} | ||||
| 
 | ||||
| 	INIT_LIST_HEAD(&md->list); | ||||
| 	mutex_init(&md->mutex); | ||||
| 	dev->msi.data = md; | ||||
|  | @ -351,6 +359,20 @@ unsigned int msi_get_virq(struct device *dev, unsigned int index) | |||
| EXPORT_SYMBOL_GPL(msi_get_virq); | ||||
| 
 | ||||
| #ifdef CONFIG_SYSFS | ||||
| static struct attribute *msi_dev_attrs[] = { | ||||
| 	NULL | ||||
| }; | ||||
| 
 | ||||
| static const struct attribute_group msi_irqs_group = { | ||||
| 	.name	= "msi_irqs", | ||||
| 	.attrs	= msi_dev_attrs, | ||||
| }; | ||||
| 
 | ||||
| static inline int msi_sysfs_create_group(struct device *dev) | ||||
| { | ||||
| 	return devm_device_add_group(dev, &msi_irqs_group); | ||||
| } | ||||
| 
 | ||||
| static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr, | ||||
| 			     char *buf) | ||||
| { | ||||
|  | @ -360,97 +382,74 @@ static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr, | |||
| 	return sysfs_emit(buf, "%s\n", is_msix ? "msix" : "msi"); | ||||
| } | ||||
| 
 | ||||
| /**
 | ||||
|  * msi_populate_sysfs - Populate msi_irqs sysfs entries for devices | ||||
|  * @dev:	The device(PCI, platform etc) who will get sysfs entries | ||||
|  */ | ||||
| static const struct attribute_group **msi_populate_sysfs(struct device *dev) | ||||
| static void msi_sysfs_remove_desc(struct device *dev, struct msi_desc *desc) | ||||
| { | ||||
| 	const struct attribute_group **msi_irq_groups; | ||||
| 	struct attribute **msi_attrs, *msi_attr; | ||||
| 	struct device_attribute *msi_dev_attr; | ||||
| 	struct attribute_group *msi_irq_group; | ||||
| 	struct msi_desc *entry; | ||||
| 	int ret = -ENOMEM; | ||||
| 	int num_msi = 0; | ||||
| 	int count = 0; | ||||
| 	struct device_attribute *attrs = desc->sysfs_attrs; | ||||
| 	int i; | ||||
| 
 | ||||
| 	/* Determine how many msi entries we have */ | ||||
| 	msi_for_each_desc(entry, dev, MSI_DESC_ALL) | ||||
| 		num_msi += entry->nvec_used; | ||||
| 	if (!num_msi) | ||||
| 		return NULL; | ||||
| 	if (!attrs) | ||||
| 		return; | ||||
| 
 | ||||
| 	/* Dynamically create the MSI attributes for the device */ | ||||
| 	msi_attrs = kcalloc(num_msi + 1, sizeof(void *), GFP_KERNEL); | ||||
| 	if (!msi_attrs) | ||||
| 		return ERR_PTR(-ENOMEM); | ||||
| 
 | ||||
| 	msi_for_each_desc(entry, dev, MSI_DESC_ALL) { | ||||
| 		for (i = 0; i < entry->nvec_used; i++) { | ||||
| 			msi_dev_attr = kzalloc(sizeof(*msi_dev_attr), GFP_KERNEL); | ||||
| 			if (!msi_dev_attr) | ||||
| 				goto error_attrs; | ||||
| 			msi_attrs[count] = &msi_dev_attr->attr; | ||||
| 
 | ||||
| 			sysfs_attr_init(&msi_dev_attr->attr); | ||||
| 			msi_dev_attr->attr.name = kasprintf(GFP_KERNEL, "%d", | ||||
| 							    entry->irq + i); | ||||
| 			if (!msi_dev_attr->attr.name) | ||||
| 				goto error_attrs; | ||||
| 			msi_dev_attr->attr.mode = 0444; | ||||
| 			msi_dev_attr->show = msi_mode_show; | ||||
| 			++count; | ||||
| 	desc->sysfs_attrs = NULL; | ||||
| 	for (i = 0; i < desc->nvec_used; i++) { | ||||
| 		if (attrs[i].show) | ||||
| 			sysfs_remove_file_from_group(&dev->kobj, &attrs[i].attr, msi_irqs_group.name); | ||||
| 		kfree(attrs[i].attr.name); | ||||
| 	} | ||||
| 	} | ||||
| 
 | ||||
| 	msi_irq_group = kzalloc(sizeof(*msi_irq_group), GFP_KERNEL); | ||||
| 	if (!msi_irq_group) | ||||
| 		goto error_attrs; | ||||
| 	msi_irq_group->name = "msi_irqs"; | ||||
| 	msi_irq_group->attrs = msi_attrs; | ||||
| 
 | ||||
| 	msi_irq_groups = kcalloc(2, sizeof(void *), GFP_KERNEL); | ||||
| 	if (!msi_irq_groups) | ||||
| 		goto error_irq_group; | ||||
| 	msi_irq_groups[0] = msi_irq_group; | ||||
| 
 | ||||
| 	ret = sysfs_create_groups(&dev->kobj, msi_irq_groups); | ||||
| 	if (ret) | ||||
| 		goto error_irq_groups; | ||||
| 
 | ||||
| 	return msi_irq_groups; | ||||
| 
 | ||||
| error_irq_groups: | ||||
| 	kfree(msi_irq_groups); | ||||
| error_irq_group: | ||||
| 	kfree(msi_irq_group); | ||||
| error_attrs: | ||||
| 	count = 0; | ||||
| 	msi_attr = msi_attrs[count]; | ||||
| 	while (msi_attr) { | ||||
| 		msi_dev_attr = container_of(msi_attr, struct device_attribute, attr); | ||||
| 		kfree(msi_attr->name); | ||||
| 		kfree(msi_dev_attr); | ||||
| 		++count; | ||||
| 		msi_attr = msi_attrs[count]; | ||||
| 	} | ||||
| 	kfree(msi_attrs); | ||||
| 	return ERR_PTR(ret); | ||||
| 	kfree(attrs); | ||||
| } | ||||
| 
 | ||||
| static int msi_sysfs_populate_desc(struct device *dev, struct msi_desc *desc) | ||||
| { | ||||
| 	struct device_attribute *attrs; | ||||
| 	int ret, i; | ||||
| 
 | ||||
| 	attrs = kcalloc(desc->nvec_used, sizeof(*attrs), GFP_KERNEL); | ||||
| 	if (!attrs) | ||||
| 		return -ENOMEM; | ||||
| 
 | ||||
| 	desc->sysfs_attrs = attrs; | ||||
| 	for (i = 0; i < desc->nvec_used; i++) { | ||||
| 		sysfs_attr_init(&attrs[i].attr); | ||||
| 		attrs[i].attr.name = kasprintf(GFP_KERNEL, "%d", desc->irq + i); | ||||
| 		if (!attrs[i].attr.name) { | ||||
| 			ret = -ENOMEM; | ||||
| 			goto fail; | ||||
| 		} | ||||
| 
 | ||||
| 		attrs[i].attr.mode = 0444; | ||||
| 		attrs[i].show = msi_mode_show; | ||||
| 
 | ||||
| 		ret = sysfs_add_file_to_group(&dev->kobj, &attrs[i].attr, msi_irqs_group.name); | ||||
| 		if (ret) { | ||||
| 			attrs[i].show = NULL; | ||||
| 			goto fail; | ||||
| 		} | ||||
| 	} | ||||
| 	return 0; | ||||
| 
 | ||||
| fail: | ||||
| 	msi_sysfs_remove_desc(dev, desc); | ||||
| 	return ret; | ||||
| } | ||||
| 
 | ||||
| #ifdef CONFIG_PCI_MSI_ARCH_FALLBACKS | ||||
| /**
 | ||||
|  * msi_device_populate_sysfs - Populate msi_irqs sysfs entries for a device | ||||
|  * @dev:	The device (PCI, platform etc) which will get sysfs entries | ||||
|  */ | ||||
| int msi_device_populate_sysfs(struct device *dev) | ||||
| { | ||||
| 	const struct attribute_group **group = msi_populate_sysfs(dev); | ||||
| 	struct msi_desc *desc; | ||||
| 	int ret; | ||||
| 
 | ||||
| 	if (IS_ERR(group)) | ||||
| 		return PTR_ERR(group); | ||||
| 	dev->msi.data->attrs = group; | ||||
| 	msi_for_each_desc(desc, dev, MSI_DESC_ASSOCIATED) { | ||||
| 		if (desc->sysfs_attrs) | ||||
| 			continue; | ||||
| 		ret = msi_sysfs_populate_desc(dev, desc); | ||||
| 		if (ret) | ||||
| 			return ret; | ||||
| 	} | ||||
| 	return 0; | ||||
| } | ||||
| 
 | ||||
|  | @ -461,28 +460,17 @@ int msi_device_populate_sysfs(struct device *dev) | |||
|  */ | ||||
| void msi_device_destroy_sysfs(struct device *dev) | ||||
| { | ||||
| 	const struct attribute_group **msi_irq_groups = dev->msi.data->attrs; | ||||
| 	struct device_attribute *dev_attr; | ||||
| 	struct attribute **msi_attrs; | ||||
| 	int count = 0; | ||||
| 	struct msi_desc *desc; | ||||
| 
 | ||||
| 	dev->msi.data->attrs = NULL; | ||||
| 	if (!msi_irq_groups) | ||||
| 		return; | ||||
| 
 | ||||
| 	sysfs_remove_groups(&dev->kobj, msi_irq_groups); | ||||
| 	msi_attrs = msi_irq_groups[0]->attrs; | ||||
| 	while (msi_attrs[count]) { | ||||
| 		dev_attr = container_of(msi_attrs[count], struct device_attribute, attr); | ||||
| 		kfree(dev_attr->attr.name); | ||||
| 		kfree(dev_attr); | ||||
| 		++count; | ||||
| 	} | ||||
| 	kfree(msi_attrs); | ||||
| 	kfree(msi_irq_groups[0]); | ||||
| 	kfree(msi_irq_groups); | ||||
| 	msi_for_each_desc(desc, dev, MSI_DESC_ALL) | ||||
| 		msi_sysfs_remove_desc(dev, desc); | ||||
| } | ||||
| #endif | ||||
| #endif /* CONFIG_PCI_MSI_ARCH_FALLBACK */ | ||||
| #else /* CONFIG_SYSFS */ | ||||
| static inline int msi_sysfs_create_group(struct device *dev) { return 0; } | ||||
| static inline int msi_sysfs_populate_desc(struct device *dev, struct msi_desc *desc) { return 0; } | ||||
| static inline void msi_sysfs_remove_desc(struct device *dev, struct msi_desc *desc) { } | ||||
| #endif /* !CONFIG_SYSFS */ | ||||
| 
 | ||||
| #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN | ||||
| static inline void irq_chip_write_msi_msg(struct irq_data *data, | ||||
|  | @ -914,6 +902,12 @@ int __msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev, | |||
| 			ret = msi_init_virq(domain, virq + i, vflags); | ||||
| 			if (ret) | ||||
| 				return ret; | ||||
| 
 | ||||
| 			if (info->flags & MSI_FLAG_DEV_SYSFS) { | ||||
| 				ret = msi_sysfs_populate_desc(dev, desc); | ||||
| 				if (ret) | ||||
| 					return ret; | ||||
| 			} | ||||
| 		} | ||||
| 		allocated++; | ||||
| 	} | ||||
|  | @ -958,17 +952,6 @@ int msi_domain_alloc_irqs_descs_locked(struct irq_domain *domain, struct device | |||
| 
 | ||||
| 	ret = ops->domain_alloc_irqs(domain, dev, nvec); | ||||
| 	if (ret) | ||||
| 		goto cleanup; | ||||
| 
 | ||||
| 	if (!(info->flags & MSI_FLAG_DEV_SYSFS)) | ||||
| 		return 0; | ||||
| 
 | ||||
| 	ret = msi_device_populate_sysfs(dev); | ||||
| 	if (ret) | ||||
| 		goto cleanup; | ||||
| 	return 0; | ||||
| 
 | ||||
| cleanup: | ||||
| 		msi_domain_free_irqs_descs_locked(domain, dev); | ||||
| 	return ret; | ||||
| } | ||||
|  | @ -994,6 +977,7 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev, int nve | |||
| 
 | ||||
| void __msi_domain_free_irqs(struct irq_domain *domain, struct device *dev) | ||||
| { | ||||
| 	struct msi_domain_info *info = domain->host_data; | ||||
| 	struct irq_data *irqd; | ||||
| 	struct msi_desc *desc; | ||||
| 	int i; | ||||
|  | @ -1008,6 +992,8 @@ void __msi_domain_free_irqs(struct irq_domain *domain, struct device *dev) | |||
| 		} | ||||
| 
 | ||||
| 		irq_domain_free_irqs(desc->irq, desc->nvec_used); | ||||
| 		if (info->flags & MSI_FLAG_DEV_SYSFS) | ||||
| 			msi_sysfs_remove_desc(dev, desc); | ||||
| 		desc->irq = 0; | ||||
| 	} | ||||
| } | ||||
|  | @ -1036,8 +1022,6 @@ void msi_domain_free_irqs_descs_locked(struct irq_domain *domain, struct device | |||
| 
 | ||||
| 	lockdep_assert_held(&dev->msi.data->mutex); | ||||
| 
 | ||||
| 	if (info->flags & MSI_FLAG_DEV_SYSFS) | ||||
| 		msi_device_destroy_sysfs(dev); | ||||
| 	ops->domain_free_irqs(domain, dev); | ||||
| 	msi_domain_free_msi_descs(info, dev); | ||||
| } | ||||
|  |  | |||
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	 Thomas Gleixner
						Thomas Gleixner