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Message-ID: <20130224040556.GA15339@core.coreip.homeip.net>
Date: Sat, 23 Feb 2013 20:05:57 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Tejun Heo <tj@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org
Subject: [RFC/PATCH] devres: allow adding custom actions to the stack
Sometimes drivers need to execute one-off actions in their error handling
or device teardown paths. An example would be toggling a GPIO line to
reset the controlled device into predefined state.
To allow performing such actions when using managed resources let's allow
adding them to stack/group of devres resources.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
drivers/base/devres.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/device.h | 4 +++
2 files changed, 78 insertions(+)
diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 6683906..507379e 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -671,6 +671,80 @@ int devres_release_group(struct device *dev, void *id)
EXPORT_SYMBOL_GPL(devres_release_group);
/*
+ * Custom devres actions allow inserting a simple function call
+ * into the teadown sequence.
+ */
+
+struct action_devres {
+ void *data;
+ void (*action)(void *);
+};
+
+static int devm_action_match(struct device *dev, void *res, void *p)
+{
+ struct action_devres *devres = res;
+ struct action_devres *target = p;
+
+ return devres->action == target->action &&
+ devres->data == target->data;
+}
+
+static void devm_action_release(struct device *dev, void *res)
+{
+ struct action_devres *devres = res;
+
+ devres->action(devres->data);
+}
+
+/**
+ * devm_add_action() - add a custom action to list of managed resources
+ * @dev: Device that owns the action
+ * @action: Function that should be called
+ * @data: Pointer to data passed to @action implementation
+ *
+ * This adds a custom action to the list of managed resources so that
+ * it gets executed as part of standard resource unwinding.
+ */
+int devm_add_action(struct device *dev, void (*action)(void *), void *data)
+{
+ struct action_devres *devres;
+
+ devres = devres_alloc(devm_action_release,
+ sizeof(struct action_devres), GFP_KERNEL);
+ if (!devres)
+ return -ENOMEM;
+
+ devres->data = data;
+ devres->action = action;
+
+ devres_add(dev, devres);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devm_add_action);
+
+/**
+ * devm_remove_action() - removes previously added custom action
+ * @dev: Device that owns the action
+ * @action: Function implementing the action
+ * @data: Pointer to data passed to @action implementation
+ *
+ * Removes instance of @action previously added by devm_add_action().
+ * Both action and data should match one of the existing entries.
+ */
+void devm_remove_action(struct device *dev, void (*action)(void *), void *data)
+{
+ struct action_devres devres = {
+ .data = data,
+ .action = action,
+ };
+
+ WARN_ON(devres_destroy(dev, devm_action_release, devm_action_match,
+ &devres));
+
+}
+EXPORT_SYMBOL_GPL(devm_remove_action);
+
+/*
* Managed kzalloc/kfree
*/
static void devm_kzalloc_release(struct device *dev, void *res)
diff --git a/include/linux/device.h b/include/linux/device.h
index 2fbf088..ba7c802 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -578,6 +578,10 @@ extern void devm_kfree(struct device *dev, void *p);
void __iomem *devm_request_and_ioremap(struct device *dev,
struct resource *res);
+/* allows to add/remove a custom action to devres stack */
+int devm_add_action(struct device *dev, void (*action)(void *), void *data);
+void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
+
struct device_dma_parameters {
/*
* a low level driver may set these to teach IOMMU code about
--
1.7.11.7
--
Dmitry
--
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