Retry on ENODATA errors

A particular device in a particular system is known to fail
with an ENODATA errno when another entity is using the same
path to access it.  Add it to the retry list so that
phosphor-hwmon will retry and hopefully be able to get a
clean read.  Even for devices where this contention isn't
the case, the code may as well retry as opposed to trying
once and giving up.

Resolves openbmc/openbmc#2645

Change-Id: Ib7aaaa14be33a33794a8c62d6991f77ab65a2ffa
Signed-off-by: Matt Spinler <spinler@us.ibm.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/sysfs.cpp b/sysfs.cpp
index 369d2e7..8b7ee48 100644
--- a/sysfs.cpp
+++ b/sysfs.cpp
@@ -62,6 +62,14 @@ static constexpr auto retryableErrors = {
      * and kill this process.
      */
     ENODEV,
+
+    /*
+     * Some devices return this when they are busy doing
+     * something else.  Even if being busy isn't the cause,
+     * a retry still gives this app a shot at getting data
+     * as opposed to failing out on the first try.
+     */
+    ENODATA,
 };
 
 static const auto emptyString = ""s;