Add an additional bit flag to the device struct named "dead". This additional flag provides a guarantee that when a device_del is executed on a given interface an async worker will not attempt to attach the driver following the earlier device_del call. Previously this guarantee was not present and could result in the device_del call attempting to remove a driver from an interface only to have the async worker attempt to probe the driver later when it finally completes the asynchronous probe call.
One additional change added was that I pulled the check for dev->driver out of the __device_attach_driver call and instead placed it in the __device_attach_async_helper call. This was motivated by the fact that the only other caller of this, __device_attach, had already taken the device_lock() and checked for dev->driver. Instead of testing for this twice in this path it makes more sense to just consolidate the dev->dead and dev->driver checks together into one set of checks. Reviewed-by: Dan Williams <[email protected]> Signed-off-by: Alexander Duyck <[email protected]> --- drivers/base/core.c | 11 +++++++++++ drivers/base/dd.c | 22 +++++++++++----------- include/linux/device.h | 5 +++++ 3 files changed, 27 insertions(+), 11 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 0073b09bb99f..950e25495726 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2080,6 +2080,17 @@ void device_del(struct device *dev) struct kobject *glue_dir = NULL; struct class_interface *class_intf; + /* + * Hold the device lock and set the "dead" flag to guarantee that + * the update behavior is consistent with the other bitfields near + * it and that we cannot have an asynchronous probe routine trying + * to run while we are tearing out the bus/class/sysfs from + * underneath the device. + */ + device_lock(dev); + dev->dead = true; + device_unlock(dev); + /* Notify clients of device removal. This call must come * before dpm_sysfs_remove(). */ diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 88713f182086..74c194ac99df 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -731,15 +731,6 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) bool async_allowed; int ret; - /* - * Check if device has already been claimed. This may - * happen with driver loading, device discovery/registration, - * and deferred probe processing happens all at once with - * multiple threads. - */ - if (dev->driver) - return -EBUSY; - ret = driver_match_device(drv, dev); if (ret == 0) { /* no match */ @@ -774,6 +765,15 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) device_lock(dev); + /* + * Check if device has already been removed or claimed. This may + * happen with driver loading, device discovery/registration, + * and deferred probe processing happens all at once with + * multiple threads. + */ + if (dev->dead || dev->driver) + goto out_unlock; + if (dev->parent) pm_runtime_get_sync(dev->parent); @@ -784,7 +784,7 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) if (dev->parent) pm_runtime_put(dev->parent); - +out_unlock: device_unlock(dev); put_device(dev); @@ -897,7 +897,7 @@ static int __driver_attach(struct device *dev, void *data) if (dev->parent && dev->bus->need_parent_lock) device_lock(dev->parent); device_lock(dev); - if (!dev->driver) + if (!dev->dead && !dev->driver) driver_probe_device(drv, dev); device_unlock(dev); if (dev->parent && dev->bus->need_parent_lock) diff --git a/include/linux/device.h b/include/linux/device.h index 1b25c7a43f4c..f73dad81e811 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -957,6 +957,10 @@ struct dev_links_info { * device. * @dma_coherent: this particular device is dma coherent, even if the * architecture supports non-coherent devices. + * @dead: This device is currently either in the process of or has + * been removed from the system. Any asynchronous events + * scheduled for this device should exit without taking any + * action. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information @@ -1051,6 +1055,7 @@ struct device { defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) bool dma_coherent:1; #endif + bool dead:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj)
