Hi Rafael,

On Monday, August 05, 2019 17:59, Rafael J. Wysocki wrote:

On Wednesday, July 24, 2019 9:47:20 AM CEST Ran Wang wrote:

quoted

Some user might want to go through all registered wakeup sources and
doing things accordingly. For example, SoC PM driver might need to do
HW programming to prevent powering down specific IP which wakeup
source depending on. So add this API to help walk through all
registered wakeup source objects on that list and return them one by one.

Signed-off-by: Ran Wang <redacted>
---
Change in v5:
	- Update commit message, add decription of walk through all wakeup
	source objects.
	- Add SCU protection in function wakeup_source_get_next().
	- Rename wakeup_source member 'attached_dev' to 'dev' and move it

up

quoted

	(before wakeirq).

Change in v4:
	- None.

Change in v3:
	- Adjust indentation of *attached_dev;.

Change in v2:
	- None.

 drivers/base/power/wakeup.c | 24 ++++++++++++++++++++++++
 include/linux/pm_wakeup.h   |  3 +++
 2 files changed, 27 insertions(+)

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index ee31d4f..2fba891 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c

@@ -14,6 +14,7 @@
 #include <linux/suspend.h>
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
+#include <linux/of_device.h>
 #include <linux/pm_wakeirq.h>
 #include <trace/events/power.h>

@@ -226,6 +227,28 @@ void wakeup_source_unregister(struct

wakeup_source *ws)

quoted

 	}
 }
 EXPORT_SYMBOL_GPL(wakeup_source_unregister);
+/**
+ * wakeup_source_get_next - Get next wakeup source from the list
+ * @ws: Previous wakeup source object, null means caller want first one.
+ */
+struct wakeup_source *wakeup_source_get_next(struct wakeup_source
+*ws) {
+	struct list_head *ws_head = &wakeup_sources;
+	struct wakeup_source *next_ws = NULL;
+	int idx;
+
+	idx = srcu_read_lock(&wakeup_srcu);
+	if (ws)
+		next_ws = list_next_or_null_rcu(ws_head, &ws->entry,
+				struct wakeup_source, entry);
+	else
+		next_ws = list_entry_rcu(ws_head->next,
+				struct wakeup_source, entry);
+	srcu_read_unlock(&wakeup_srcu, idx);
+

This is incorrect.

The SRCU cannot be unlocked until the caller of this is done with the object
returned by it, or that object can be freed while it is still being accessed.

Thanks for the comment. Looks like I was not fully understanding your point on
v4 discussion. So I will implement 3 APIs by referring wakeup_sources_stats_seq_start/next/stop()
 

Besides, this patch conflicts with some general wakeup sources changes in the
works, so it needs to be deferred and rebased on top of those changes.

Could you please tell me which is the right code base I should developing on?
I just tried applying v5 patch on latest git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git branch master (d1abaeb Linux 5.3-rc5)
and no conflict encountered.

Thanks & Regards,
Ran