* [PATCH net-next] selftests: net: add ctl_file_write() helper
@ 2026-09-04 17:41 Jakub Kicinski
2026-09-04 23:34 ` Bobby Eshleman
0 siblings, 1 reply; 2+ messages in thread
From: Jakub Kicinski @ 2026-09-04 17:41 UTC (permalink / raw)
To: davem
Cc: netdev, edumazet, pabeni, andrew+netdev, horms, Jakub Kicinski,
shuah, cjubran, cratiu, noren, willemb, petrm, linux-kselftest
Setting a sysctl or a sysfs attribute for the duration of a test and
putting the old value back has been open coded multiple times.
We generally avoid creating library helpers but this one is very
common, and the defer is a little tricky as using the same function
for defer as the initial write leads to an infinite loop (not that
I would ever make such mistake!)
Some of the conversions are not identical, but arguably ctl_file_write()
semantics are more correct.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: shuah@kernel.org
CC: cjubran@nvidia.com
CC: cratiu@nvidia.com
CC: noren@nvidia.com
CC: willemb@google.com
CC: petrm@nvidia.com
CC: linux-kselftest@vger.kernel.org
---
tools/testing/selftests/drivers/net/gro.py | 17 +++---------
.../drivers/net/hw/devlink_rate_tc_bw.py | 5 ++--
tools/testing/selftests/drivers/net/hw/irq.py | 11 ++------
.../drivers/net/hw/lib/py/__init__.py | 4 +--
.../selftests/drivers/net/hw/toeplitz.py | 10 +++----
.../selftests/drivers/net/lib/py/__init__.py | 4 +--
.../selftests/drivers/net/ring_reconfig.py | 26 ++++---------------
.../testing/selftests/net/lib/py/__init__.py | 4 +--
tools/testing/selftests/net/lib/py/utils.py | 22 ++++++++++++++++
9 files changed, 44 insertions(+), 59 deletions(-)
diff --git a/tools/testing/selftests/drivers/net/gro.py b/tools/testing/selftests/drivers/net/gro.py
index 6ab8c97880d1..e0b21703cc3c 100755
--- a/tools/testing/selftests/drivers/net/gro.py
+++ b/tools/testing/selftests/drivers/net/gro.py
@@ -42,7 +42,7 @@ import re
from lib.py import ksft_run, ksft_exit, ksft_pr
from lib.py import NetDrvEpEnv, KsftFailEx, KsftXfailEx
from lib.py import NetdevFamily, EthtoolFamily
-from lib.py import bkg, cmd, defer, ethtool, ip
+from lib.py import bkg, cmd, ctl_file_write, defer, ethtool, ip
from lib.py import ksft_variants, KsftNamedVariant
@@ -79,17 +79,6 @@ GRO_DPORT = 8000
return getattr(cfg, attr)
-def _write_defer_restore(cfg, path, val, defer_undo=False):
- with open(path, "r", encoding="utf-8") as fp:
- orig_val = fp.read().strip()
- if str(val) == orig_val:
- return
- with open(path, "w", encoding="utf-8") as fp:
- fp.write(val)
- if defer_undo:
- defer(_write_defer_restore, cfg, path, orig_val)
-
-
def _set_mtu_restore(dev, mtu, host):
if dev['mtu'] < mtu:
ip(f"link set dev {dev['ifname']} mtu {mtu}", host=host)
@@ -244,8 +233,8 @@ def _run_gro_bin(cfg, test_name, protocol=None, num_flows=None,
flush_path = f"/sys/class/net/{cfg.ifname}/gro_flush_timeout"
irq_path = f"/sys/class/net/{cfg.ifname}/napi_defer_hard_irqs"
- _write_defer_restore(cfg, flush_path, "200000", defer_undo=True)
- _write_defer_restore(cfg, irq_path, "10", defer_undo=True)
+ ctl_file_write(flush_path, "200000")
+ ctl_file_write(irq_path, "10")
_set_ethtool_feat(cfg.ifname, cfg.feat,
{"generic-receive-offload": True,
diff --git a/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py b/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py
index 4e4faa9275bb..38d712755257 100755
--- a/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py
+++ b/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py
@@ -63,7 +63,7 @@ from lib.py import ksft_pr, ksft_run, ksft_exit
from lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
from lib.py import NetDrvEpEnv, DevlinkFamily
from lib.py import NlError
-from lib.py import cmd, defer, ethtool, ip
+from lib.py import cmd, ctl_file_write, defer, ethtool, ip
from lib.py import Iperf3Runner
@@ -113,8 +113,7 @@ from lib.py import Iperf3Runner
except Exception as exc:
raise KsftSkipEx(f"Failed to enable switchdev mode on {cfg.pci}") from exc
try:
- cmd(f"echo 1 > /sys/class/net/{cfg.ifname}/device/sriov_numvfs", shell=True)
- defer(cmd, f"echo 0 > /sys/class/net/{cfg.ifname}/device/sriov_numvfs", shell=True)
+ ctl_file_write(f"/sys/class/net/{cfg.ifname}/device/sriov_numvfs", 1)
except Exception as exc:
raise KsftSkipEx(f"Failed to enable SR-IOV on {cfg.ifname}") from exc
diff --git a/tools/testing/selftests/drivers/net/hw/irq.py b/tools/testing/selftests/drivers/net/hw/irq.py
index 0699d6a8b4e2..3d1c56b51054 100755
--- a/tools/testing/selftests/drivers/net/hw/irq.py
+++ b/tools/testing/selftests/drivers/net/hw/irq.py
@@ -7,7 +7,7 @@ from lib.py import KsftSkipEx
from lib.py import ksft_disruptive
from lib.py import EthtoolFamily, NetdevFamily
from lib.py import NetDrvEnv
-from lib.py import cmd, ip, defer
+from lib.py import cmd, ctl_file_write, ip
def read_affinity(irq) -> str:
@@ -15,12 +15,6 @@ from lib.py import cmd, ip, defer
return fp.read().lstrip("0,").strip()
-def write_affinity(irq, what) -> str:
- if what != read_affinity(irq):
- with open(f'/proc/irq/{irq}/smp_affinity', 'w') as fp:
- fp.write(what)
-
-
def check_irqs_reported(cfg) -> None:
""" Check that device reports IRQs for NAPI instances """
napis = cfg.netnl.napi_get({"ifindex": cfg.ifindex}, dump=True)
@@ -41,8 +35,7 @@ from lib.py import cmd, ip, defer
old = read_affinity(n['irq'])
# pick an affinity that's not the current one
new = "3" if old != "3" else "5"
- write_affinity(n['irq'], new)
- defer(write_affinity, n['irq'], old)
+ ctl_file_write(f"/proc/irq/{n['irq']}/smp_affinity", new)
reconfig_cb(cfg)
diff --git a/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py b/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
index 8a58cb17cc06..81e1d1865cd5 100644
--- a/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
@@ -24,7 +24,7 @@ KSFT_DIR = (Path(__file__).parent / "../../../../..").resolve()
from net.lib.py import CmdExitFailure
from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
fd_read_timeout, ip, rand_port, rand_ports, wait_port_listen, \
- wait_file, tool
+ wait_file, ctl_file_write, tool
from net.lib.py import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
@@ -40,7 +40,7 @@ KSFT_DIR = (Path(__file__).parent / "../../../../..").resolve()
"CmdExitFailure",
"bkg", "cmd", "bpftool", "bpftrace", "defer", "ethtool",
"fd_read_timeout", "ip", "rand_port", "rand_ports",
- "wait_port_listen", "wait_file", "tool",
+ "wait_port_listen", "wait_file", "ctl_file_write", "tool",
"bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
"KsftSkipEx", "KsftFailEx", "KsftXfailEx",
"ksft_disruptive", "ksft_exit", "ksft_pr", "ksft_run",
diff --git a/tools/testing/selftests/drivers/net/hw/toeplitz.py b/tools/testing/selftests/drivers/net/hw/toeplitz.py
index 571732198b93..962d1aca2bc9 100755
--- a/tools/testing/selftests/drivers/net/hw/toeplitz.py
+++ b/tools/testing/selftests/drivers/net/hw/toeplitz.py
@@ -13,7 +13,7 @@ import os
import socket
from lib.py import ksft_run, ksft_exit, ksft_pr
from lib.py import NetDrvEpEnv, EthtoolFamily, NetdevFamily
-from lib.py import cmd, bkg, rand_port, defer
+from lib.py import cmd, bkg, ctl_file_write, rand_port, defer
from lib.py import ksft_in
from lib.py import ksft_variants, KsftNamedVariant, KsftSkipEx, KsftFailEx
@@ -113,7 +113,7 @@ QUEUE_CAP = 8
def _configure_rps(cfg, rps_cpus):
- """Configure RPS for all Rx queues."""
+ """Configure RPS for all Rx queues, restored at the end of the test."""
mask = 0
for cpu in rps_cpus:
@@ -123,9 +123,8 @@ QUEUE_CAP = 8
# Set RPS bitmap for all rx queues
for rps_file in glob.glob(f"/sys/class/net/{cfg.ifname}/queues/rx-*/rps_cpus"):
- with open(rps_file, "w", encoding="utf-8") as fp:
- # sysfs expects hex without '0x' prefix, toeplitz.c needs the prefix
- fp.write(mask[2:])
+ # sysfs expects hex without '0x' prefix, toeplitz.c needs the prefix
+ ctl_file_write(rps_file, mask[2:])
return mask
@@ -208,7 +207,6 @@ QUEUE_CAP = 8
# Get CPUs not used by Rx queues and configure them for RPS
rps_cpus = _get_unused_rps_cpus(cfg, count=2)
rps_mask = _configure_rps(cfg, rps_cpus)
- defer(_configure_rps, cfg, [])
rx_cmd += ["-r", rps_mask]
ksft_pr(f"RPS using CPUs: {rps_cpus}, mask: {rps_mask}")
diff --git a/tools/testing/selftests/drivers/net/lib/py/__init__.py b/tools/testing/selftests/drivers/net/lib/py/__init__.py
index ee903bcf3207..591b1e6c7eea 100644
--- a/tools/testing/selftests/drivers/net/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/lib/py/__init__.py
@@ -24,7 +24,7 @@ KSFT_DIR = (Path(__file__).parent / "../../../..").resolve()
from net.lib.py import CmdExitFailure
from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
fd_read_timeout, ip, rand_port, rand_ports, tc, wait_port_listen, \
- wait_file
+ wait_file, ctl_file_write
from net.lib.py import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
@@ -38,7 +38,7 @@ KSFT_DIR = (Path(__file__).parent / "../../../..").resolve()
"CmdExitFailure",
"bkg", "cmd", "bpftool", "bpftrace", "defer", "ethtool",
"fd_read_timeout", "ip", "rand_port", "rand_ports", "tc",
- "wait_port_listen", "wait_file",
+ "wait_port_listen", "wait_file", "ctl_file_write",
"bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
"KsftSkipEx", "KsftFailEx", "KsftXfailEx",
"ksft_disruptive", "ksft_exit", "ksft_pr", "ksft_run",
diff --git a/tools/testing/selftests/drivers/net/ring_reconfig.py b/tools/testing/selftests/drivers/net/ring_reconfig.py
index 2bc329b77134..6682d4badfbf 100755
--- a/tools/testing/selftests/drivers/net/ring_reconfig.py
+++ b/tools/testing/selftests/drivers/net/ring_reconfig.py
@@ -13,7 +13,7 @@ from lib.py import ksft_run, ksft_exit, ksft_pr
from lib.py import ksft_eq
from lib.py import KsftSkipEx, KsftXfailEx
from lib.py import NetDrvEpEnv, EthtoolFamily, GenerateTraffic
-from lib.py import cmd, defer, rand_port, tc, NlError
+from lib.py import cmd, ctl_file_write, defer, rand_port, tc, NlError
# Added in Python 3.13; fallback to 61 for x86/ARM/MIPS
SO_TXTIME = getattr(socket, "SO_TXTIME", 61)
@@ -166,22 +166,6 @@ MAX_TX_RING = 1024
GenerateTraffic(cfg).wait_pkts_and_stop(10000)
-def _write_file(path, val):
- """Write val to a file."""
- with open(path, "w", encoding="utf-8") as fp:
- fp.write(str(val))
-
-
-def _write_sysfs(path, val):
- """Write val to a sysfs file, restoring the original value on exit."""
- with open(path, "r", encoding="utf-8") as fp:
- orig_val = fp.read().strip()
- if str(val) == orig_val:
- return
- _write_file(path, val)
- defer(_write_file, path, orig_val)
-
-
def _get_qdisc_backlog(cfg, mq_handle, queue):
"""Return the qdisc backlog (bytes) for the given TX queue's leaf."""
target_parent = f"{mq_handle}{queue + 1:x}"
@@ -342,8 +326,8 @@ MAX_TX_RING = 1024
# Slow completions so the ring stays full after FQ releases packets
napi_defer = f"/sys/class/net/{cfg.ifname}/napi_defer_hard_irqs"
gro_timeout = f"/sys/class/net/{cfg.ifname}/gro_flush_timeout"
- _write_sysfs(napi_defer, 100)
- _write_sysfs(gro_timeout, 1000000000)
+ ctl_file_write(napi_defer, 100)
+ ctl_file_write(gro_timeout, 1000000000)
port = rand_port()
# A single flow must overflow the ring, so send twice the ring depth and
@@ -384,8 +368,8 @@ MAX_TX_RING = 1024
cfg.eth.rings_set(ehdr | {'tx': tx_cur})
# Let completions proceed normally
- _write_sysfs(napi_defer, 0)
- _write_sysfs(gro_timeout, 0)
+ ctl_file_write(napi_defer, 0)
+ ctl_file_write(gro_timeout, 0)
# Poll for backlog to drain
for _ in range(100):
diff --git a/tools/testing/selftests/net/lib/py/__init__.py b/tools/testing/selftests/net/lib/py/__init__.py
index 34935886b6ad..71df5880b356 100644
--- a/tools/testing/selftests/net/lib/py/__init__.py
+++ b/tools/testing/selftests/net/lib/py/__init__.py
@@ -14,7 +14,7 @@ from .netns import NetNS, NetNSEnter, UserNetNS
from .nsim import NetdevSim, NetdevSimDev
from .utils import CmdExitFailure, fd_read_timeout, cmd, bkg, defer, \
bpftool, ip, ethtool, bpftrace, rand_port, rand_ports, wait_port_listen, \
- wait_file, tool, tc
+ ctl_file_write, wait_file, tool, tc
from .bpf import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
from .ynl import NlError, NlctrlFamily, YnlFamily, \
EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily, RtnlRouteFamily
@@ -29,7 +29,7 @@ __all__ = ["KSRC",
"NetNS", "NetNSEnter", "UserNetNS",
"CmdExitFailure", "fd_read_timeout", "cmd", "bkg", "defer",
"bpftool", "ip", "ethtool", "bpftrace", "rand_port", "rand_ports",
- "wait_port_listen", "wait_file", "tool", "tc",
+ "wait_port_listen", "ctl_file_write", "wait_file", "tool", "tc",
"bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
"NetdevSim", "NetdevSimDev",
"NetshaperFamily", "DevlinkFamily", "PSPFamily", "NlError",
diff --git a/tools/testing/selftests/net/lib/py/utils.py b/tools/testing/selftests/net/lib/py/utils.py
index 184bb04343f6..1727bc418073 100644
--- a/tools/testing/selftests/net/lib/py/utils.py
+++ b/tools/testing/selftests/net/lib/py/utils.py
@@ -357,6 +357,28 @@ GLOBAL_DEFER_ARMED = False
time.sleep(sleep)
+def _ctl_file_write(path, val):
+ with open(path, "w", encoding="utf-8") as fp:
+ fp.write(str(val))
+
+
+def ctl_file_write(path, val):
+ """
+ Write @val to a control file - a sysctl, a sysfs attribute, configfs...
+ and defer() restoring the old value, so needs a defer queue.
+
+ Writing a value which is already set is skipped, there is nothing
+ to restore in that case.
+ """
+ with open(path, "r", encoding="utf-8") as fp:
+ old = fp.read().strip()
+ if old == str(val):
+ return
+
+ _ctl_file_write(path, val)
+ defer(_ctl_file_write, path, old)
+
+
def wait_file(fname, test_fn, sleep=0.005, deadline=5, encoding='utf-8'):
"""
Wait for file contents on the local system to satisfy a condition.
--
2.55.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net-next] selftests: net: add ctl_file_write() helper
2026-09-04 17:41 [PATCH net-next] selftests: net: add ctl_file_write() helper Jakub Kicinski
@ 2026-09-04 23:34 ` Bobby Eshleman
0 siblings, 0 replies; 2+ messages in thread
From: Bobby Eshleman @ 2026-09-04 23:34 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, shuah,
cjubran, cratiu, noren, willemb, petrm, linux-kselftest
On Fri, Sep 04, 2026 at 10:41:34AM -0700, Jakub Kicinski wrote:
> Setting a sysctl or a sysfs attribute for the duration of a test and
> putting the old value back has been open coded multiple times.
>
> We generally avoid creating library helpers but this one is very
> common, and the defer is a little tricky as using the same function
> for defer as the initial write leads to an infinite loop (not that
> I would ever make such mistake!)
>
> Some of the conversions are not identical, but arguably ctl_file_write()
> semantics are more correct.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: shuah@kernel.org
> CC: cjubran@nvidia.com
> CC: cratiu@nvidia.com
> CC: noren@nvidia.com
> CC: willemb@google.com
> CC: petrm@nvidia.com
> CC: linux-kselftest@vger.kernel.org
> ---
> tools/testing/selftests/drivers/net/gro.py | 17 +++---------
> .../drivers/net/hw/devlink_rate_tc_bw.py | 5 ++--
> tools/testing/selftests/drivers/net/hw/irq.py | 11 ++------
> .../drivers/net/hw/lib/py/__init__.py | 4 +--
> .../selftests/drivers/net/hw/toeplitz.py | 10 +++----
> .../selftests/drivers/net/lib/py/__init__.py | 4 +--
> .../selftests/drivers/net/ring_reconfig.py | 26 ++++---------------
> .../testing/selftests/net/lib/py/__init__.py | 4 +--
> tools/testing/selftests/net/lib/py/utils.py | 22 ++++++++++++++++
> 9 files changed, 44 insertions(+), 59 deletions(-)
>
> diff --git a/tools/testing/selftests/drivers/net/gro.py b/tools/testing/selftests/drivers/net/gro.py
> index 6ab8c97880d1..e0b21703cc3c 100755
> --- a/tools/testing/selftests/drivers/net/gro.py
> +++ b/tools/testing/selftests/drivers/net/gro.py
> @@ -42,7 +42,7 @@ import re
> from lib.py import ksft_run, ksft_exit, ksft_pr
> from lib.py import NetDrvEpEnv, KsftFailEx, KsftXfailEx
> from lib.py import NetdevFamily, EthtoolFamily
> -from lib.py import bkg, cmd, defer, ethtool, ip
> +from lib.py import bkg, cmd, ctl_file_write, defer, ethtool, ip
> from lib.py import ksft_variants, KsftNamedVariant
>
>
> @@ -79,17 +79,6 @@ GRO_DPORT = 8000
> return getattr(cfg, attr)
>
>
> -def _write_defer_restore(cfg, path, val, defer_undo=False):
> - with open(path, "r", encoding="utf-8") as fp:
> - orig_val = fp.read().strip()
> - if str(val) == orig_val:
> - return
> - with open(path, "w", encoding="utf-8") as fp:
> - fp.write(val)
> - if defer_undo:
> - defer(_write_defer_restore, cfg, path, orig_val)
> -
> -
> def _set_mtu_restore(dev, mtu, host):
> if dev['mtu'] < mtu:
> ip(f"link set dev {dev['ifname']} mtu {mtu}", host=host)
> @@ -244,8 +233,8 @@ def _run_gro_bin(cfg, test_name, protocol=None, num_flows=None,
> flush_path = f"/sys/class/net/{cfg.ifname}/gro_flush_timeout"
> irq_path = f"/sys/class/net/{cfg.ifname}/napi_defer_hard_irqs"
>
> - _write_defer_restore(cfg, flush_path, "200000", defer_undo=True)
> - _write_defer_restore(cfg, irq_path, "10", defer_undo=True)
> + ctl_file_write(flush_path, "200000")
> + ctl_file_write(irq_path, "10")
>
> _set_ethtool_feat(cfg.ifname, cfg.feat,
> {"generic-receive-offload": True,
> diff --git a/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py b/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py
> index 4e4faa9275bb..38d712755257 100755
> --- a/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py
> +++ b/tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py
> @@ -63,7 +63,7 @@ from lib.py import ksft_pr, ksft_run, ksft_exit
> from lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
> from lib.py import NetDrvEpEnv, DevlinkFamily
> from lib.py import NlError
> -from lib.py import cmd, defer, ethtool, ip
> +from lib.py import cmd, ctl_file_write, defer, ethtool, ip
> from lib.py import Iperf3Runner
>
>
> @@ -113,8 +113,7 @@ from lib.py import Iperf3Runner
> except Exception as exc:
> raise KsftSkipEx(f"Failed to enable switchdev mode on {cfg.pci}") from exc
> try:
> - cmd(f"echo 1 > /sys/class/net/{cfg.ifname}/device/sriov_numvfs", shell=True)
> - defer(cmd, f"echo 0 > /sys/class/net/{cfg.ifname}/device/sriov_numvfs", shell=True)
> + ctl_file_write(f"/sys/class/net/{cfg.ifname}/device/sriov_numvfs", 1)
> except Exception as exc:
> raise KsftSkipEx(f"Failed to enable SR-IOV on {cfg.ifname}") from exc
>
> diff --git a/tools/testing/selftests/drivers/net/hw/irq.py b/tools/testing/selftests/drivers/net/hw/irq.py
> index 0699d6a8b4e2..3d1c56b51054 100755
> --- a/tools/testing/selftests/drivers/net/hw/irq.py
> +++ b/tools/testing/selftests/drivers/net/hw/irq.py
> @@ -7,7 +7,7 @@ from lib.py import KsftSkipEx
> from lib.py import ksft_disruptive
> from lib.py import EthtoolFamily, NetdevFamily
> from lib.py import NetDrvEnv
> -from lib.py import cmd, ip, defer
> +from lib.py import cmd, ctl_file_write, ip
>
>
> def read_affinity(irq) -> str:
> @@ -15,12 +15,6 @@ from lib.py import cmd, ip, defer
> return fp.read().lstrip("0,").strip()
>
>
> -def write_affinity(irq, what) -> str:
> - if what != read_affinity(irq):
> - with open(f'/proc/irq/{irq}/smp_affinity', 'w') as fp:
> - fp.write(what)
> -
> -
> def check_irqs_reported(cfg) -> None:
> """ Check that device reports IRQs for NAPI instances """
> napis = cfg.netnl.napi_get({"ifindex": cfg.ifindex}, dump=True)
> @@ -41,8 +35,7 @@ from lib.py import cmd, ip, defer
> old = read_affinity(n['irq'])
> # pick an affinity that's not the current one
> new = "3" if old != "3" else "5"
> - write_affinity(n['irq'], new)
> - defer(write_affinity, n['irq'], old)
> + ctl_file_write(f"/proc/irq/{n['irq']}/smp_affinity", new)
This one might miss the ctl_file_write's "old == str(val)" case, where
old is still prepended with zeroes (e.g., 0000,0000,0003)?
The rest LGTM.
Best,
Bobby
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2026-09-04 17:41 [PATCH net-next] selftests: net: add ctl_file_write() helper Jakub Kicinski
2026-09-04 23:34 ` Bobby Eshleman
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