attribute_container_device_trigger invokes callbacks that may fail for one or more classdev's, for instance, the transport_add_class_device callback, called during transport creation, does memory allocation. This information, though, is not propagated to upper layers, and any driver using the attribute_container_device_trigger API will not know whether any, some, or all callbacks succeeded.
This patch implements a safe version of this dispatcher, to either succeed all the callbacks or revert to the original state. Signed-off-by: Gabriel Krisman Bertazi <[email protected]> --- drivers/base/attribute_container.c | 103 ++++++++++++++++++++++++++++ include/linux/attribute_container.h | 7 ++ 2 files changed, 110 insertions(+) diff --git a/drivers/base/attribute_container.c b/drivers/base/attribute_container.c index 20736aaa0e69..f7bd0f4db13d 100644 --- a/drivers/base/attribute_container.c +++ b/drivers/base/attribute_container.c @@ -236,6 +236,109 @@ attribute_container_remove_device(struct device *dev, mutex_unlock(&attribute_container_mutex); } +static int +do_attribute_container_device_trigger_safe(struct device *dev, + struct attribute_container *cont, + int (*fn)(struct attribute_container *, + struct device *, struct device *), + int (*undo)(struct attribute_container *, + struct device *, struct device *)) +{ + int ret; + struct internal_container *ic, *failed; + struct klist_iter iter; + + if (attribute_container_no_classdevs(cont)) + return fn(cont, dev, NULL); + + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (dev == ic->classdev.parent) { + ret = fn(cont, dev, &ic->classdev); + if (ret) { + failed = ic; + klist_iter_exit(&iter); + goto fail; + } + } + } + return 0; + +fail: + if (!undo) + return ret; + + /* Attempt to undo the work partially done. */ + klist_for_each_entry(ic, &cont->containers, node, &iter) { + if (ic == failed) { + klist_iter_exit(&iter); + break; + } + if (dev == ic->classdev.parent) + undo(cont, dev, &ic->classdev); + } + return ret; +} + +/** + * attribute_container_device_trigger_safe - execute a trigger for each + * matching classdev or fail all of them. + * + * @dev: The generic device to run the trigger for + * @fn the function to execute for each classdev. + * @undo A function to undo the work previously done in case of error + * + * This function is a safe version of + * attribute_container_device_trigger. It stops on the first error and + * undo the partial work that has been done, on previous classdev. It + * is guaranteed that either they all succeeded, or none of them + * succeeded. + */ +int +attribute_container_device_trigger_safe(struct device *dev, + int (*fn)(struct attribute_container *, + struct device *, + struct device *), + int (*undo)(struct attribute_container *, + struct device *, + struct device *)) +{ + struct attribute_container *cont, *failed = NULL; + int ret = 0; + + mutex_lock(&attribute_container_mutex); + + list_for_each_entry(cont, &attribute_container_list, node) { + + if (!cont->match(cont, dev)) + continue; + + ret = do_attribute_container_device_trigger_safe(dev, cont, + fn, undo); + if (ret) { + failed = cont; + break; + } + } + + if (ret && !WARN_ON(!undo)) { + list_for_each_entry(cont, &attribute_container_list, node) { + + if (failed == cont) + break; + + if (!cont->match(cont, dev)) + continue; + + do_attribute_container_device_trigger_safe(dev, cont, + undo, NULL); + } + } + + mutex_unlock(&attribute_container_mutex); + return ret; + +} + /** * attribute_container_device_trigger - execute a trigger for each matching classdev * diff --git a/include/linux/attribute_container.h b/include/linux/attribute_container.h index d12bb2153cd6..e4004d1e6725 100644 --- a/include/linux/attribute_container.h +++ b/include/linux/attribute_container.h @@ -54,6 +54,13 @@ void attribute_container_device_trigger(struct device *dev, int (*fn)(struct attribute_container *, struct device *, struct device *)); +int attribute_container_device_trigger_safe(struct device *dev, + int (*fn)(struct attribute_container *, + struct device *, + struct device *), + int (*undo)(struct attribute_container *, + struct device *, + struct device *)); void attribute_container_trigger(struct device *dev, int (*fn)(struct attribute_container *, struct device *)); -- 2.24.1 -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/open-iscsi/20200106185817.640331-2-krisman%40collabora.com.
