[PATCH 4.9 07/48] PM: wakeup: simplify the output logic of pm_show_wakelocks()

Greg Kroah-Hartman
2022-02-07T11:13:57Z

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit c9d967b2ce40d71e968eb839f36c936b8a9cf1ea upstream.

The buffer handling in pm_show_wakelocks() is tricky, and hopefully
correct. Ensure it really is correct by using sysfs_emit_at() which
handles all of the tricky string handling logic in a PAGE_SIZE buffer
for us automatically as this is a sysfs file being read from.

Reviewed-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/power/wakelock.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

--- a/kernel/power/wakelock.c
+++ b/kernel/power/wakelock.c
@@ -38,23 +38,19 @@ ssize_t pm_show_wakelocks(char *buf, boo
{
struct rb_node *node;
struct wakelock *wl;
- char *str = buf;
- char *end = buf + PAGE_SIZE;
+ int len = 0;

mutex_lock(&wakelocks_lock);

for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
wl = rb_entry(node, struct wakelock, node);
if (wl->ws.active == show_active)
- str += scnprintf(str, end - str, "%s ", wl->name);
+ len += sysfs_emit_at(buf, len, "%s ", wl->name);
}
- if (str > buf)
- str--;
-
- str += scnprintf(str, end - str, "\n");
+ len += sysfs_emit_at(buf, len, "\n");

mutex_unlock(&wakelocks_lock);
- return (str - buf);
+ return len;
}

#if CONFIG_PM_WAKELOCKS_LIMIT > 0