From bbc780f8bab52fef1784151d3c4982cb1143edd2 Mon Sep 17 00:00:00 2001 From: David Herrmann Date: Thu, 21 Nov 2013 20:15:48 +0100 Subject: driver core: fix device_create() error path We call put_device() in the error path, which is fine for dev==NULL. However, in case kobject_set_name_vargs() fails, we have dev!=NULL but device_initialized() wasn't called, yet. Fix this by splitting device_register() into explicit calls to device_add() and an early call to device_initialize(). Signed-off-by: David Herrmann Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index 67b180d855b2..aab43fbb8336 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1603,6 +1603,7 @@ device_create_groups_vargs(struct class *class, struct device *parent, goto error; } + device_initialize(dev); dev->devt = devt; dev->class = class; dev->parent = parent; @@ -1614,7 +1615,7 @@ device_create_groups_vargs(struct class *class, struct device *parent, if (retval) goto error; - retval = device_register(dev); + retval = device_add(dev); if (retval) goto error; -- cgit v1.2.3 From ecfbf6fd9c03be7dfe3eafc3846641b9d463607b Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 12 Dec 2013 06:11:02 +0100 Subject: Driver core: Fix device_add_attrs() error code path If the addition of dev_attr_online fails, device_add_attrs() should remove device attribute groups as well as type and class attribute groups before returning an error code. Make that happen. Signed-off-by: Rafael J. Wysocki Acked-by: Toshi Kani Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index aab43fbb8336..2b567177ef78 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -491,11 +491,13 @@ static int device_add_attrs(struct device *dev) if (device_supports_offline(dev) && !dev->offline_disabled) { error = device_create_file(dev, &dev_attr_online); if (error) - goto err_remove_type_groups; + goto err_remove_dev_groups; } return 0; + err_remove_dev_groups: + device_remove_groups(dev, dev->groups); err_remove_type_groups: if (type) device_remove_groups(dev, type->groups); -- cgit v1.2.3 From 1ae06819c77cff1ea2833c94f8c093fe8a5c79db Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 10 Jan 2014 08:57:27 -0500 Subject: kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref and deactivates using __kernfs_deactivate_self(), removes the self node, and restores active ref to the dead node using __kernfs_reactivate_self() so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: Updated to use __kernfs_{de|re}activate_self(). Signed-off-by: Tejun Heo Cc: Alan Stern Cc: kbuild test robot Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index 2b567177ef78..9db57afcf81f 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -570,6 +570,23 @@ void device_remove_file(struct device *dev, } EXPORT_SYMBOL_GPL(device_remove_file); +/** + * device_remove_file_self - remove sysfs attribute file from its own method. + * @dev: device. + * @attr: device attribute descriptor. + * + * See kernfs_remove_self() for details. + */ +bool device_remove_file_self(struct device *dev, + const struct device_attribute *attr) +{ + if (dev) + return sysfs_remove_file_self(&dev->kobj, &attr->attr); + else + return false; +} +EXPORT_SYMBOL_GPL(device_remove_file_self); + /** * device_create_bin_file - create sysfs binary attribute file for device. * @dev: device. -- cgit v1.2.3 From d1ba277e79889085a2faec3b68b91ce89c63f888 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 10 Jan 2014 08:57:31 -0500 Subject: sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner() All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 33 --------------------------------- 1 file changed, 33 deletions(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index 9db57afcf81f..4195364f9fdd 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -615,39 +615,6 @@ void device_remove_bin_file(struct device *dev, } EXPORT_SYMBOL_GPL(device_remove_bin_file); -/** - * device_schedule_callback_owner - helper to schedule a callback for a device - * @dev: device. - * @func: callback function to invoke later. - * @owner: module owning the callback routine - * - * Attribute methods must not unregister themselves or their parent device - * (which would amount to the same thing). Attempts to do so will deadlock, - * since unregistration is mutually exclusive with driver callbacks. - * - * Instead methods can call this routine, which will attempt to allocate - * and schedule a workqueue request to call back @func with @dev as its - * argument in the workqueue's process context. @dev will be pinned until - * @func returns. - * - * This routine is usually called via the inline device_schedule_callback(), - * which automatically sets @owner to THIS_MODULE. - * - * Returns 0 if the request was submitted, -ENOMEM if storage could not - * be allocated, -ENODEV if a reference to @owner isn't available. - * - * NOTE: This routine won't work if CONFIG_SYSFS isn't set! It uses an - * underlying sysfs routine (since it is intended for use by attribute - * methods), and if sysfs isn't available you'll get nothing but -ENOSYS. - */ -int device_schedule_callback_owner(struct device *dev, - void (*func)(struct device *), struct module *owner) -{ - return sysfs_schedule_callback(&dev->kobj, - (void (*)(void *)) func, dev, owner); -} -EXPORT_SYMBOL_GPL(device_schedule_callback_owner); - static void klist_children_get(struct klist_node *n) { struct device_private *p = to_device_private_parent(n); -- cgit v1.2.3 From a30f82b7ebc87cdec3ef48303278f02970086118 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 13 Jan 2014 13:51:36 -0800 Subject: Revert "sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index 4195364f9fdd..9db57afcf81f 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -615,6 +615,39 @@ void device_remove_bin_file(struct device *dev, } EXPORT_SYMBOL_GPL(device_remove_bin_file); +/** + * device_schedule_callback_owner - helper to schedule a callback for a device + * @dev: device. + * @func: callback function to invoke later. + * @owner: module owning the callback routine + * + * Attribute methods must not unregister themselves or their parent device + * (which would amount to the same thing). Attempts to do so will deadlock, + * since unregistration is mutually exclusive with driver callbacks. + * + * Instead methods can call this routine, which will attempt to allocate + * and schedule a workqueue request to call back @func with @dev as its + * argument in the workqueue's process context. @dev will be pinned until + * @func returns. + * + * This routine is usually called via the inline device_schedule_callback(), + * which automatically sets @owner to THIS_MODULE. + * + * Returns 0 if the request was submitted, -ENOMEM if storage could not + * be allocated, -ENODEV if a reference to @owner isn't available. + * + * NOTE: This routine won't work if CONFIG_SYSFS isn't set! It uses an + * underlying sysfs routine (since it is intended for use by attribute + * methods), and if sysfs isn't available you'll get nothing but -ENOSYS. + */ +int device_schedule_callback_owner(struct device *dev, + void (*func)(struct device *), struct module *owner) +{ + return sysfs_schedule_callback(&dev->kobj, + (void (*)(void *)) func, dev, owner); +} +EXPORT_SYMBOL_GPL(device_schedule_callback_owner); + static void klist_children_get(struct klist_node *n) { struct device_private *p = to_device_private_parent(n); -- cgit v1.2.3 From a9f138b0e537de55933335d580ebd38c2bc53c47 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 13 Jan 2014 14:05:13 -0800 Subject: Revert "kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers" This reverts commit 1ae06819c77cff1ea2833c94f8c093fe8a5c79db. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo Cc: Alan Stern Cc: kbuild test robot Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 17 ----------------- 1 file changed, 17 deletions(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index 9db57afcf81f..2b567177ef78 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -570,23 +570,6 @@ void device_remove_file(struct device *dev, } EXPORT_SYMBOL_GPL(device_remove_file); -/** - * device_remove_file_self - remove sysfs attribute file from its own method. - * @dev: device. - * @attr: device attribute descriptor. - * - * See kernfs_remove_self() for details. - */ -bool device_remove_file_self(struct device *dev, - const struct device_attribute *attr) -{ - if (dev) - return sysfs_remove_file_self(&dev->kobj, &attr->attr); - else - return false; -} -EXPORT_SYMBOL_GPL(device_remove_file_self); - /** * device_create_bin_file - create sysfs binary attribute file for device. * @dev: device. -- cgit v1.2.3