wifi: Check whether dev node is accessible or not before opening

wifi framework tries to open dev node WIFI_DRIVER_STATE_CTRL_PARAM
as part of initialization/turn on. But this dev node may not be
present/not accessible by then. So check for the
existence/accessibility of dev node by retrying few times to
avoid possible race condition between creation and accessing
of this node.

Test: manual test
Bug: 72196764
Change-Id: Iff283bf4f8dcf305785891d142e50afd6dc65875

1 files changed, 12 insertions, 0 deletions

diff --git a/libwifi_hal/wifi_hal_common.cpp b/libwifi_hal/wifi_hal_common.cpp
index 14a0b6247..599434f82 100644
--- a/libwifi_hal/wifi_hal_common.cpp
+++ b/libwifi_hal/wifi_hal_common.cpp
@@ -93,8 +93,20 @@ int wifi_change_driver_state(const char *state) {
   int len;
   int fd;
   int ret = 0;
+  int count = 5; /* wait at most 1 second for completion */
 
   if (!state) return -1;
+
+  do {
+    if (access(WIFI_DRIVER_STATE_CTRL_PARAM, R_OK|W_OK) == 0)
+      break;
+    usleep(200000);
+  } while (--count > 0);
+    if (count == 0) {
+      PLOG(ERROR) << "Failed to access driver state control param " << strerror(errno) << ", " << errno;
+      return -1;
+  }
+
   fd = TEMP_FAILURE_RETRY(open(WIFI_DRIVER_STATE_CTRL_PARAM, O_WRONLY));
   if (fd < 0) {
     PLOG(ERROR) << "Failed to open driver state control param";