A CXL driver fix making its way upstream[1], makes a repeat write of an endpoint decoder to the region targetN attribute that already holds it succeed without changing the region. Without the fix, that write fails, leaves the region half detached from the endpoint's ports, and a later write can crash the kernel.
Add a test case to backstop that fix. Write target0 twice on a partially populated region and check that the second write succeeds and leaves the region's decoders attached. [1] https://lore.kernel.org/linux-cxl/920d80735a449f93a1f17a8bca4c25e4b302cb42.1792989098.git.alison.schofi...@intel.com/ Signed-off-by: Alison Schofield <[email protected]> --- Changes since v1: - Expect a repeat write to succeed, as the v2 kernel fix makes it a no-op test/cxl-region-sysfs.sh | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/test/cxl-region-sysfs.sh b/test/cxl-region-sysfs.sh index db1a163efb30..cb5e6ba53e71 100644 --- a/test/cxl-region-sysfs.sh +++ b/test/cxl-region-sysfs.sh @@ -87,9 +87,19 @@ do select(.mode == \"pmem\") | .decoder") done -# attach all endpoint decoders to the region -pos=0 -for i in ${endpoint[@]} +# a repeat write of an attached endpoint decoder must succeed and leave +# every decoder between it and the root attached +echo "${endpoint[0]}" > "/sys/bus/cxl/devices/$region/target0" +nr_attached=$(cat /sys/bus/cxl/devices/decoder*/region | grep -cx "$region") +if ! echo "${endpoint[0]}" > "/sys/bus/cxl/devices/$region/target0"; then + err "$LINENO: repeat write of ${endpoint[0]} to target0 failed" +fi +nr=$(cat /sys/bus/cxl/devices/decoder*/region | grep -cx "$region") +[ "$nr" -ne "$nr_attached" ] && err "$LINENO: $nr of $nr_attached decoders still attached" + +# attach the remaining endpoint decoders to the region +pos=1 +for i in ${endpoint[@]:1} do echo $i > /sys/bus/cxl/devices/$region/target$pos pos=$((pos+1)) -- 2.37.3
