Add wiphy_delayed_work_pending() to check if any delayed work timer is
pending, that can be used to be sure that wiphy_delayed_work_queue()
won't postpone an already pending delayed work.
Signed-off-by: Remi Pommarel <repk@xxxxxxxxxxxx>
---
include/net/cfg80211.h | 44 ++++++++++++++++++++++++++++++++++++++++++
net/wireless/core.c | 7 +++++++
2 files changed, 51 insertions(+)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 192d72c8b465..01697b624095 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -6129,6 +6129,50 @@ void wiphy_delayed_work_cancel(struct wiphy *wiphy,
void wiphy_delayed_work_flush(struct wiphy *wiphy,
struct wiphy_delayed_work *dwork);
+/**
+ * wiphy_delayed_work_pending - Find out whether a wiphy delayable
+ * work item is currently pending.
+ *
+ * @wiphy: the wiphy, for debug purposes
+ * @dwork: the delayed work in question
+ *
+ * return value: true if timer is pending, false otherwise
+ *
+ * How wiphy_delayed_work_queue() works is by setting a timer which
+ * when it expires calls wiphy_work_queue() to queue the wiphy work.
+ * Because wiphy_delayed_work_queue() uses mod_timer(), if it is
+ * called twice and the second call happens before the first call
+ * deadline, the work will rescheduled for the second deadline and
+ * won't run before that.
+ *
+ * wiphy_delayed_work_pending() can be used to detect if calling
+ * wiphy_work_delayed_work_queue() would start a new work schedule
+ * or delayed a previous one. As seen below it cannot be used to
+ * detect precisely if the work has finished to execute nor if it
+ * is currently executing.
+ *
+ * CPU0 CPU1
+ * wiphy_delayed_work_queue(wk)
+ * mod_timer(wk->timer)
+ * wiphy_delayed_work_pending(wk) -> true
+ *
+ * [...]
+ * expire_timers(wk->timer)
+ * detach_timer(wk->timer)
+ * wiphy_delayed_work_pending(wk) -> false
+ * wk->timer->function() |
+ * wiphy_work_queue(wk) | delayed work pending
+ * list_add_tail() | returns false but
+ * queue_work(cfg80211_wiphy_work) | wk->func() has not
+ * | been run yet
+ * [...] |
+ * cfg80211_wiphy_work() |
+ * wk->func() V
+ *
+ */
+bool wiphy_delayed_work_pending(struct wiphy *wiphy,
+ struct wiphy_delayed_work *dwork);
+
/**
* enum ieee80211_ap_reg_power - regulatory power for an Access Point
*
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 4d5d351bd0b5..c9a1158dbdd1 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1704,6 +1704,13 @@ void wiphy_delayed_work_flush(struct wiphy *wiphy,
}
EXPORT_SYMBOL_GPL(wiphy_delayed_work_flush);
+bool wiphy_delayed_work_pending(struct wiphy *wiphy,
+ struct wiphy_delayed_work *dwork)
+{
+ return timer_pending(&dwork->timer);
+}
+EXPORT_SYMBOL_GPL(wiphy_delayed_work_pending);
+
static int __init cfg80211_init(void)
{
int err;
--
2.46.0
