[LTP] [PATCH] runtest/fs: Don't read files in /dev indiscriminately

Punit Agrawal punit.agrawal@arm.com
Fri May 11 19:31:56 CEST 2018

read_all_dev attempts to read 1024 bytes from all devices in /dev. As
nodes in /dev represent devices, any access can have side-effects -
sometimes fatally so, e.g., accessing /dev/port on Juno R2 and AMD
Seattle lead to synchronous external abort or SError (system error)
interrupt depending on the access pattern.

There isn't much the kernel can do about the aborts other than panic
the system.

The side-effects problem is also highlighted by the recent exclusion
added for watchdog devices. See commit 4a41aa6b48c134e ("runtest/fs:
filter /dev/watchdog* for read_all_dev by default").

It would be better to replace indiscriminate reading of /dev files
with tests targeting specific files in /dev which have defined known
behaviour, e.g., /dev/null, /dev/urandom, etc.

In the meanwhile, drop the indiscriminate reading of files in /dev.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: xuyang.jy@cn.fujitsu.com
Cc: naresh.kamboju@linaro.org
Cc: rpalethorpe@suse.com
Cc: chrubis@suse.cz
Cc: james.morse@arm.com

The test leads to panic during nightly ltp runs on internal
systems. Looking at the crash report from Naresh[0], it looks likely
that he's facing the same problem.

Please consider including in upcoming release.


[0] http://lists.linux.it/pipermail/ltp/2018-May/007954.html
 runtest/fs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/runtest/fs b/runtest/fs
index 42a9bfcbf..c7ed64fbf 100644
--- a/runtest/fs
+++ b/runtest/fs
@@ -69,7 +69,6 @@ fs_di fs_di -d $TMPDIR
 # Was not sure why it should reside in runtest/crashme and won´t get tested ever
 proc01 proc01 -m 128
-read_all_dev read_all -d /dev -e '/dev/watchdog?(0)' -q -r 10
 read_all_proc read_all -d /proc -q -r 10
 read_all_sys read_all -d /sys -q -r 10

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