6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
commit 7d4b5d7a37bdd63a5a3371b988744b060d5bb86f upstream.
In preparation for subsequent changes, introduce a specialized variant
of async_schedule_dev() that will not invoke the argument function
synchronously when it cannot be scheduled for asynchronous execution.
The new function, async_schedule_dev_nocall(), will be used for fixing
possible deadlocks in the system-wide power management core code.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@xxxxxxxxxxxxxxx> for the series.
Tested-by: Youngmin Nam <youngmin.nam@xxxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/async.h | 2 ++
kernel/async.c | 29 +++++++++++++++++++++++++++++
2 files changed, 31 insertions(+)
--- a/include/linux/async.h
+++ b/include/linux/async.h
@@ -90,6 +90,8 @@ async_schedule_dev(async_func_t func, st
return async_schedule_node(func, dev, dev_to_node(dev));
}
+bool async_schedule_dev_nocall(async_func_t func, struct device *dev);
+
/**
* async_schedule_dev_domain - A device specific version of async_schedule_domain
* @func: function to execute asynchronously
--- a/kernel/async.c
+++ b/kernel/async.c
@@ -244,6 +244,35 @@ async_cookie_t async_schedule_node(async
EXPORT_SYMBOL_GPL(async_schedule_node);
/**
+ * async_schedule_dev_nocall - A simplified variant of async_schedule_dev()
+ * @func: function to execute asynchronously
+ * @dev: device argument to be passed to function
+ *
+ * @dev is used as both the argument for the function and to provide NUMA
+ * context for where to run the function.
+ *
+ * If the asynchronous execution of @func is scheduled successfully, return
+ * true. Otherwise, do nothing and return false, unlike async_schedule_dev()
+ * that will run the function synchronously then.
+ */
+bool async_schedule_dev_nocall(async_func_t func, struct device *dev)
+{
+ struct async_entry *entry;
+
+ entry = kzalloc(sizeof(struct async_entry), GFP_KERNEL);
+
+ /* Give up if there is no memory or too much work. */
+ if (!entry || atomic_read(&entry_count) > MAX_WORK) {
+ kfree(entry);
+ return false;
+ }
+
+ __async_schedule_node_domain(func, dev, dev_to_node(dev),
+ &async_dfl_domain, entry);
+ return true;
+}
+
+/**
* async_synchronize_full - synchronize all asynchronous function calls
*
* This function waits until all asynchronous function calls have been done.
