| Message ID | 20211206210747.708877269@linutronix.de (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | genirq/msi, PCI/MSI: Spring cleaning - Part 3 | expand |
On Mon, Dec 06, 2021 at 11:51:05PM +0100, Thomas Gleixner wrote: > +++ b/kernel/irq/msi.c > @@ -127,12 +127,37 @@ int msi_setup_device_data(struct device > return -ENOMEM; > > INIT_LIST_HEAD(&md->list); > + mutex_init(&md->mutex); > dev->msi.data = md; > devres_add(dev, md); > return 0; > } > > /** > + * msi_lock_descs - Lock the MSI descriptor storage of a device > + * @dev: Device to operate on > + */ > +void msi_lock_descs(struct device *dev) > +{ > + if (WARN_ON_ONCE(!dev->msi.data)) > + return; Is this useful? Other places that call msi_lock_descs will continue on and deref null dev->msi anyhow - is the dump from the WARN_ON that much better than the oops from the null deref here: > + mutex_lock(&dev->msi.data->mutex); ? Honestly, still a bit unclear on what the community consensus is for using WARN_ON. Jason
On Wed, Dec 08 2021 at 20:47, Jason Gunthorpe wrote: > On Mon, Dec 06, 2021 at 11:51:05PM +0100, Thomas Gleixner wrote: >> +++ b/kernel/irq/msi.c >> @@ -127,12 +127,37 @@ int msi_setup_device_data(struct device >> return -ENOMEM; >> >> INIT_LIST_HEAD(&md->list); >> + mutex_init(&md->mutex); >> dev->msi.data = md; >> devres_add(dev, md); >> return 0; >> } >> >> /** >> + * msi_lock_descs - Lock the MSI descriptor storage of a device >> + * @dev: Device to operate on >> + */ >> +void msi_lock_descs(struct device *dev) >> +{ >> + if (WARN_ON_ONCE(!dev->msi.data)) >> + return; > > Is this useful? Other places that call msi_lock_descs will continue on and deref > null dev->msi anyhow - is the dump from the WARN_ON that much better > than the oops from the null deref here: > >> + mutex_lock(&dev->msi.data->mutex); I put it there for paranoia reasons and forgot to revist it later. In that case yes, it's of questionable value. Thanks, tglx
--- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -3,6 +3,7 @@ #define LINUX_MSI_H #include <linux/cpumask.h> +#include <linux/mutex.h> #include <linux/list.h> #include <linux/bits.h> #include <asm/msi.h> @@ -146,12 +147,14 @@ struct msi_desc { * @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 */ 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; }; int msi_setup_device_data(struct device *dev); @@ -173,6 +176,8 @@ static inline void msi_device_set_proper #endif unsigned int msi_get_virq(struct device *dev, unsigned int index); +void msi_lock_descs(struct device *dev); +void msi_unlock_descs(struct device *dev); /* Helpers to hide struct msi_desc implementation details */ #define msi_desc_to_dev(desc) ((desc)->dev) --- a/kernel/irq/msi.c +++ b/kernel/irq/msi.c @@ -127,12 +127,37 @@ int msi_setup_device_data(struct device return -ENOMEM; INIT_LIST_HEAD(&md->list); + mutex_init(&md->mutex); dev->msi.data = md; devres_add(dev, md); return 0; } /** + * msi_lock_descs - Lock the MSI descriptor storage of a device + * @dev: Device to operate on + */ +void msi_lock_descs(struct device *dev) +{ + if (WARN_ON_ONCE(!dev->msi.data)) + return; + mutex_lock(&dev->msi.data->mutex); +} +EXPORT_SYMBOL_GPL(msi_lock_descs); + +/** + * msi_unlock_descs - Unlock the MSI descriptor storage of a device + * @dev: Device to operate on + */ +void msi_unlock_descs(struct device *dev) +{ + if (WARN_ON_ONCE(!dev->msi.data)) + return; + mutex_unlock(&dev->msi.data->mutex); +} +EXPORT_SYMBOL_GPL(msi_unlock_descs); + +/** * msi_get_virq - Return Linux interrupt number of a MSI interrupt * @dev: Device to operate on * @index: MSI interrupt index to look for (0-based)
For upcoming runtime extensions of MSI-X interrupts it's required to protect the MSI descriptor list. Add a mutex to struct msi_device_data and provide lock/unlock functions. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- include/linux/msi.h | 5 +++++ kernel/irq/msi.c | 25 +++++++++++++++++++++++++ 2 files changed, 30 insertions(+)