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Wi-Fi HAL: fix supplicant start failed issue

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init.svc.*(hostapd, p2p_supplicant) properties are set when starting
STA or uAP via Wi-Fi HAL, after sending ctrl.start command to
property_service, thread called wifi_start_supplicant will yield cpu
for android init process to get scheduled, then init.svc.* status
is read to check if supplicant status is running

there is a chance that after scheld_yield returned, init is not
scheduled, serial value is not updated, __system_property_read got
the "stopped" status, then init is scheduled to update service status
after that back to this loop in Wi-Fi HAL, serial is updated, but
status is not reread, still used "stopped", then Wi-Fi HAL will
report supplicant start failed

as the following schedule sequence:

process A(WifiStateMachine)           process B(init)
1. ctl.start
2. scheld_yield
3. __system_proerty_read
   /*serial1, value1*/
                                      4. __system_property_update
                                         /*serial2, value2*/
5. serial1 != serial2
6. value1 == "stopped"

So after sched_yield, first check if serial is updated, then read
service status

Change-Id: I5181e0d4504c525832c033b9a35bd58ec63e1de8
Signed-off-by: jiaguo <jiaguo@marvell.com>
This commit is contained in:
jiaguo 2014-03-13 18:49:14 +08:00
parent c32be36fd0
commit 4431a1c34d
1 changed files with 10 additions and 6 deletions
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16
wifi/wifi.c
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@ -556,12 +556,16 @@ int wifi_start_supplicant(int p2p_supported)
pi = __system_property_find(supplicant_prop_name);
}
if (pi != NULL) {
__system_property_read(pi, NULL, supp_status);
if (strcmp(supp_status, "running") == 0) {
return 0;
} else if (__system_property_serial(pi) != serial &&
strcmp(supp_status, "stopped") == 0) {
return -1;
/*
* property serial updated means that init process is scheduled
* after we sched_yield, further property status checking is based on this */
if (__system_property_serial(pi) != serial) {
__system_property_read(pi, NULL, supp_status);
if (strcmp(supp_status, "running") == 0) {
return 0;
} else if (strcmp(supp_status, "stopped") == 0) {
return -1;
}
}
}
#else