[PATCH net-next] selftests: drv-net: hds: restore hds settings

[Jakub Kicinski <kuba@kernel.org>]

The test currently modifies the HDS settings and doesn't restore them.
This may cause subsequent tests to fail (or pass when they should not).
Add defer()ed reset handling.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 tools/testing/selftests/drivers/net/hds.py | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/hds.py b/tools/testing/selftests/drivers/net/hds.py
index 7c90a040ce45..abad81a88ba9 100755
--- a/tools/testing/selftests/drivers/net/hds.py
+++ b/tools/testing/selftests/drivers/net/hds.py
@@ -58,7 +58,39 @@ from lib.py import defer, ethtool, ip, random
     if 'hds-thresh' not in rings:
         raise KsftSkipEx('hds-thresh not supported by device')
 
+
+def _hds_reset(cfg, netnl, rings) -> None:
+    cur = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
+
+    arg = {'header': {'dev-index': cfg.ifindex}}
+    if cur.get('tcp-data-split') != rings.get('tcp-data-split'):
+        # Try to reset to "unknown" first, we don't know if the setting
+        # was the default or user chose it. Default seems more likely.
+        arg['tcp-data-split'] = "unknown"
+        netnl.rings_set(arg)
+        cur = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
+        if cur['tcp-data-split'] == rings['tcp-data-split']:
+            del arg['tcp-data-split']
+        else:
+            # Try the explicit setting
+            arg['tcp-data-split'] = rings['tcp-data-split']
+    if cur.get('hds-thresh') != rings.get('hds-thresh'):
+        arg['hds-thresh'] = rings['hds-thresh']
+    if len(arg) > 1:
+        netnl.rings_set(arg)
+
+
+def _defer_reset_hds(cfg, netnl) -> dict | None:
+    try:
+        rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
+        if 'hds-thresh' in rings or 'tcp-data-split' in rings:
+            defer(_hds_reset, cfg, netnl, rings)
+    except NlError as e:
+        pass
+
+
 def set_hds_enable(cfg, netnl) -> None:
+    _defer_reset_hds(cfg, netnl)
     try:
         netnl.rings_set({'header': {'dev-index': cfg.ifindex}, 'tcp-data-split': 'enabled'})
     except NlError as e:
@@ -76,6 +108,7 @@ from lib.py import defer, ethtool, ip, random
     ksft_eq('enabled', rings['tcp-data-split'])
 
 def set_hds_disable(cfg, netnl) -> None:
+    _defer_reset_hds(cfg, netnl)
     try:
         netnl.rings_set({'header': {'dev-index': cfg.ifindex}, 'tcp-data-split': 'disabled'})
     except NlError as e:
@@ -93,6 +126,7 @@ from lib.py import defer, ethtool, ip, random
     ksft_eq('disabled', rings['tcp-data-split'])
 
 def set_hds_thresh_zero(cfg, netnl) -> None:
+    _defer_reset_hds(cfg, netnl)
     try:
         netnl.rings_set({'header': {'dev-index': cfg.ifindex}, 'hds-thresh': 0})
     except NlError as e:
@@ -110,6 +144,7 @@ from lib.py import defer, ethtool, ip, random
     ksft_eq(0, rings['hds-thresh'])
 
 def set_hds_thresh_random(cfg, netnl) -> None:
+    _defer_reset_hds(cfg, netnl)
     try:
         rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
     except NlError as e:
@@ -140,6 +175,7 @@ from lib.py import defer, ethtool, ip, random
     ksft_eq(hds_thresh, rings['hds-thresh'])
 
 def set_hds_thresh_max(cfg, netnl) -> None:
+    _defer_reset_hds(cfg, netnl)
     try:
         rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
     except NlError as e:
@@ -157,6 +193,7 @@ from lib.py import defer, ethtool, ip, random
     ksft_eq(rings['hds-thresh'], rings['hds-thresh-max'])
 
 def set_hds_thresh_gt(cfg, netnl) -> None:
+    _defer_reset_hds(cfg, netnl)
     try:
         rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
     except NlError as e:
@@ -178,6 +215,7 @@ from lib.py import defer, ethtool, ip, random
     """
     mode = _get_hds_mode(cfg, netnl)
     if mode == 'enabled':
+        _defer_reset_hds(cfg, netnl)
         netnl.rings_set({'header': {'dev-index': cfg.ifindex},
                          'tcp-data-split': 'unknown'})
 
-- 
2.50.1