selftests/powerpc: Squash spurious errors due to device removal

For drivers that don't have the error handling callbacks we implement
recovery by removing the device and re-probing it. This causes the sysfs
directory for the PCI device to be removed which causes the following
spurious error to be printed when checking the PE state:

Breaking 0005:03:00.0...
./eeh-basic.sh: line 13: can't open /sys/bus/pci/devices/0005:03:00.0/eeh_pe_state: no such file
0005:03:00.0, waited 0/60
0005:03:00.0, waited 1/60
0005:03:00.0, waited 2/60
0005:03:00.0, waited 3/60
0005:03:00.0, waited 4/60
0005:03:00.0, waited 5/60
0005:03:00.0, waited 6/60
0005:03:00.0, waited 7/60
0005:03:00.0, Recovered after 8 seconds

We currently try to avoid this by checking if the PE state file exists
before reading from it. This is however inherently racy so re-work the
state checking so that we only read from the file once, and we squash any
errors that occur while reading.

Fixes: 85d86c8aa52e ("selftests/powerpc: Add basic EEH selftest")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200727010127.23698-1-oohall@gmail.com

diff --git a/tools/testing/selftests/powerpc/eeh/eeh-functions.sh b/tools/testing/selftests/powerpc/eeh/eeh-functions.sh
index f52ed92..00dc32c 100755 (executable)
--- a/tools/testing/selftests/powerpc/eeh/eeh-functions.sh
+++ b/tools/testing/selftests/powerpc/eeh/eeh-functions.sh
@@ -5,12 +5,17 @@ pe_ok() {
        local dev="$1"
        local path="/sys/bus/pci/devices/$dev/eeh_pe_state"
 
-       if ! [ -e "$path" ] ; then
+       # if a driver doesn't support the error handling callbacks then the
+       # device is recovered by removing and re-probing it. This causes the
+       # sysfs directory to disappear so read the PE state once and squash
+       # any potential error messages
+       local eeh_state="$(cat $path 2>/dev/null)"
+       if [ -z "$eeh_state" ]; then
                return 1;
        fi
 
-       local fw_state="$(cut -d' ' -f1 < $path)"
-       local sw_state="$(cut -d' ' -f2 < $path)"
+       local fw_state="$(echo $eeh_state | cut -d' ' -f1)"
+       local sw_state="$(echo $eeh_state | cut -d' ' -f2)"
 
        # If EEH_PE_ISOLATED or EEH_PE_RECOVERING are set then the PE is in an
        # error state or being recovered. Either way, not ok.