selftests: drv-net: test random value for hds-thresh

hds.py has been testing 0(set_hds_thresh_zero()),
MAX(set_hds_thresh_max()), GT(set_hds_thresh_gt()) values for hds-thresh.
However if a hds-thresh value was already 0, set_hds_thresh_zero()
can't test properly.
So, it tests random value first and then tests 0, MAX, GT values.

Testing bnxt:
    TAP version 13
    1..13
    ok 1 hds.get_hds
    ok 2 hds.get_hds_thresh
    ok 3 hds.set_hds_disable # SKIP disabling of HDS not supported by
    the device
    ok 4 hds.set_hds_enable
    ok 5 hds.set_hds_thresh_random
    ok 6 hds.set_hds_thresh_zero
    ok 7 hds.set_hds_thresh_max
    ok 8 hds.set_hds_thresh_gt
    ok 9 hds.set_xdp
    ok 10 hds.enabled_set_xdp
    ok 11 hds.ioctl
    ok 12 hds.ioctl_set_xdp
    ok 13 hds.ioctl_enabled_set_xdp
    # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:1 error:0

Testing lo:
    TAP version 13
    1..13
    ok 1 hds.get_hds # SKIP tcp-data-split not supported by device
    ok 2 hds.get_hds_thresh # SKIP hds-thresh not supported by device
    ok 3 hds.set_hds_disable # SKIP ring-set not supported by the device
    ok 4 hds.set_hds_enable # SKIP ring-set not supported by the device
    ok 5 hds.set_hds_thresh_random # SKIP hds-thresh not supported by
    device
    ok 6 hds.set_hds_thresh_zero # SKIP ring-set not supported by the
    device
    ok 7 hds.set_hds_thresh_max # SKIP hds-thresh not supported by
    device
    ok 8 hds.set_hds_thresh_gt # SKIP hds-thresh not supported by device
    ok 9 hds.set_xdp # SKIP tcp-data-split not supported by device
    ok 10 hds.enabled_set_xdp # SKIP tcp-data-split not supported by
    device
    ok 11 hds.ioctl # SKIP tcp-data-split not supported by device
    ok 12 hds.ioctl_set_xdp # SKIP tcp-data-split not supported by
    device
    ok 13 hds.ioctl_enabled_set_xdp # SKIP tcp-data-split not supported
    by device
    # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:13 error:0

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://patch.msgid.link/20250404122126.1555648-3-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/drivers/net/hds.py

@@ -6,7 +6,7 @@
 from lib.py import ksft_run, ksft_exit, ksft_eq, ksft_raises, KsftSkipEx
 from lib.py import CmdExitFailure, EthtoolFamily, NlError
 from lib.py import NetDrvEnv
-from lib.py import defer, ethtool, ip
+from lib.py import defer, ethtool, ip, random
 
 
 def _get_hds_mode(cfg, netnl) -> str:
@@ -109,6 +109,36 @@ def set_hds_thresh_zero(cfg, netnl) -> None:
 
     ksft_eq(0, rings['hds-thresh'])
 
+def set_hds_thresh_random(cfg, netnl) -> None:
+    try:
+        rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
+    except NlError as e:
+        raise KsftSkipEx('ring-get not supported by device')
+    if 'hds-thresh' not in rings:
+        raise KsftSkipEx('hds-thresh not supported by device')
+    if 'hds-thresh-max' not in rings:
+        raise KsftSkipEx('hds-thresh-max not defined by device')
+
+    if rings['hds-thresh-max'] < 2:
+        raise KsftSkipEx('hds-thresh-max is too small')
+    elif rings['hds-thresh-max'] == 2:
+        hds_thresh = 1
+    else:
+        while True:
+            hds_thresh = random.randint(1, rings['hds-thresh-max'] - 1)
+            if hds_thresh != rings['hds-thresh']:
+                break
+
+    try:
+        netnl.rings_set({'header': {'dev-index': cfg.ifindex}, 'hds-thresh': hds_thresh})
+    except NlError as e:
+        if e.error == errno.EINVAL:
+            raise KsftSkipEx("hds-thresh-set not supported by the device")
+        elif e.error == errno.EOPNOTSUPP:
+            raise KsftSkipEx("ring-set not supported by the device")
+    rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
+    ksft_eq(hds_thresh, rings['hds-thresh'])
+
 def set_hds_thresh_max(cfg, netnl) -> None:
     try:
         rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
@@ -243,6 +273,7 @@ def main() -> None:
                   get_hds_thresh,
                   set_hds_disable,
                   set_hds_enable,
+                  set_hds_thresh_random,
                   set_hds_thresh_zero,
                   set_hds_thresh_max,
                   set_hds_thresh_gt,