commit db76d49cf7740500db4e677046a9175e0b3f173e
author Brandon Kim <brandonkim@google.com> Mon Jun 17 11:53:04 2019 -0700
committer Brandon Kim <brandonkim@google.com> Tue Jun 18 10:27:45 2019 -0700
tree 0e7457c4754ba3302c98f5d5f41c44a1f349072d
parent d0ce7925d77c56c142f64b2c6ae55f0020c06ba8

sensor: Implement RAII object for GPIO unlock and lock

There is a bug where GPIO lock may not be called if there is an
exception after GPIO unlock. Adding an RAII object for GPIO lock
and replacing the current usage of gpioUnlock, gpioLock in
sensor.cpp and mainloop.cpp.

Bug: openbmc/phosphor-hwmon#11
Signed-off-by: Brandon Kim <brandonkim@google.com>
Change-Id: Ica094e716a6ff9dc99165651f83fc496d5ed5a17

sensor.cpp

diff --git a/sensor.cpp b/sensor.cpp
index d45f23a..89f8330 100644
--- a/sensor.cpp
+++ b/sensor.cpp
@@ -146,7 +146,8 @@
     // its status is functional, read the input value.
     if (!statusIface || (statusIface && statusIface->functional()))
     {
-        unlockGpio();
+        // RAII object for GPIO unlock / lock
+        GpioLock gpioLock(getGpio());
 
         // Retry for up to a second if device is busy
         // or has a transient error.
@@ -154,7 +155,6 @@
                               hwmon::entry::cinput, std::get<size_t>(retryIO),
                               std::get<std::chrono::milliseconds>(retryIO));
 
-        lockGpio();
         val = adjustValue(val);
     }
 
@@ -243,7 +243,17 @@
     return iface;
 }
 
-void Sensor::unlockGpio()
+GpioLock::GpioLock(const gpioplus::HandleInterface* handle) : _handle(handle)
+{
+    unlockGpio();
+}
+
+GpioLock::~GpioLock()
+{
+    lockGpio();
+}
+
+void GpioLock::unlockGpio()
 {
     if (_handle)
     {
@@ -252,7 +262,7 @@
     }
 }
 
-void Sensor::lockGpio()
+void GpioLock::lockGpio()
 {
     if (_handle)
     {