Incorrect deletion of PID file, duplicate background processes?

[Jaak Ristioja]

Hi,

It appears that wpa_priv deletes the PID file of an existing background 
process. This may lead to multiple wpa_priv background processes being 
spawned:

# grep -H ^ /run/wpa_priv.pid; wpa_priv -B -P /run/wpa_priv.pid 
nl80211:wlan0; grep -H ^ /run/wpa_priv.pid; pgrep wpa_priv
grep: /run/wpa_priv.pid: No such file or directory
/run/wpa_priv.pid:24534
24534
# grep -H ^ /run/wpa_priv.pid; wpa_priv -B -P /run/wpa_priv.pid 
nl80211:wlan0; grep -H ^ /run/wpa_priv.pid; pgrep wpa_priv
/run/wpa_priv.pid:24534
Socket exists and seems to be in use - cannot override it
Delete '/var/run/wpa_priv/wlan0' manually if it is not used anymore
grep: /run/wpa_priv.pid: No such file or directory
24534
# grep -H ^ /run/wpa_priv.pid; wpa_priv -B -P /run/wpa_priv.pid 
nl80211:wlan0; grep -H ^ /run/wpa_priv.pid; pgrep wpa_priv
grep: /run/wpa_priv.pid: No such file or directory
/run/wpa_priv.pid:24543
24534
24543

After a quick look at the source code, it seems that wpa_supplicant and 
possibly other programs may be also have similar behavior.


Best regards,
Jaak Ristioja