blktests nvme/039 failure

[Shin'ichiro Kawasaki]

Hello Alan,

I noticed that recently nvme/039 fails on my system occasionally (around 40%).
The failure messages are as follows:

nvme/039 => nvme0n1 (test error logging)                     [failed]
    runtime  0.176s  ...  0.167s
    --- tests/nvme/039.out      2023-04-06 10:11:07.925670528 +0900
    +++ /home/shin/Blktests/blktests/results/nvme0n1/nvme/039.out.bad   2023-04-10 20:15:07.679538017 +0900
    @@ -1,5 +1,2 @@
     Running nvme/039
    - Read(0x2) @ LBA 0, 1 blocks, Unrecovered Read Error (sct 0x2 / sc 0x81) DNR
    - Read(0x2) @ LBA 0, 1 blocks, Unknown (sct 0x3 / sc 0x75) DNR
    - Write(0x1) @ LBA 0, 1 blocks, Write Fault (sct 0x2 / sc 0x80) DNR
     Test complete

nvme/039 => nvme0n1 (test error logging)                     [failed]
    runtime  0.167s  ...  0.199s
    --- tests/nvme/039.out      2023-04-06 10:11:07.925670528 +0900
    +++ /home/shin/Blktests/blktests/results/nvme0n1/nvme/039.out.bad   2023-04-10 20:15:09.114539650 +0900
    @@ -1,5 +1,4 @@
     Running nvme/039
    - Read(0x2) @ LBA 0, 1 blocks, Unrecovered Read Error (sct 0x2 / sc 0x81) DNR
      Read(0x2) @ LBA 0, 1 blocks, Unknown (sct 0x3 / sc 0x75) DNR
      Write(0x1) @ LBA 0, 1 blocks, Write Fault (sct 0x2 / sc 0x80) DNR
     Test complete

It looks that expected error messages were not reported.

I suspect that the time duration is too short between error injection enable
and I/O to trigger the error. With the one line change below to add wait after
the error injection enable, the failures disappear. Do you think such wait is
the valid fix?

 tests/nvme/rc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/nvme/rc b/tests/nvme/rc
index 210a82a..7043c23 100644
--- a/tests/nvme/rc
+++ b/tests/nvme/rc
@@ -652,6 +652,7 @@ _nvme_enable_err_inject()
         echo "$4" > /sys/kernel/debug/"$1"/fault_inject/dont_retry
         echo "$5" > /sys/kernel/debug/"$1"/fault_inject/status
         echo "$6" > /sys/kernel/debug/"$1"/fault_inject/times
+	sleep 0.1
 }
 
 _nvme_disable_err_inject()
-- 
2.39.2