Re: [syzbot] Re: [wireless?] INFO: task hung in cfg80211_event_work (4)

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Subject: Re: [wireless?] INFO: task hung in cfg80211_event_work (4)
Author: lizhi.xu@xxxxxxxxxxxxx

When hwsim and regulatory are used simultaneously, a race occurs for the
lock "wiphy.mtx", it cause hung in cfg80211_event_work.
The hwsim is a developer testing tool, so maybe using mutex_trylock
insead of mutex_lock is more reasonable.

#syz test

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 661adfc77644..4e8a6c76b12d 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -331,7 +331,8 @@ static void cfg80211_event_work(struct work_struct *work)
 	rdev = container_of(work, struct cfg80211_registered_device,
 			    event_work);
 
-	wiphy_lock(&rdev->wiphy);
+	if (!mutex_trylock(&rdev->wiphy.mtx))
+		return;
 	cfg80211_process_rdev_events(rdev);
 	wiphy_unlock(&rdev->wiphy);
 }