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[Smartswitch] Kill stale initramfs udevd process before updating udevd rules #17

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[Smartswitch] Kill stale initramfs udevd process before updating udevd rules #17

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ed2fca7
Kill stale initramfs udevd process before updating udevd rules
tirupatihemanth Mar 19, 2026
bb994c3
Update NVIDIA Header
tirupatihemanth Mar 20, 2026
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26 changes: 24 additions & 2 deletions platform/mellanox/smartswitch/dpu-udev-manager/dpu-udev-manager.sh
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#!/usr/bin/env bash
#!/bin/bash
#
# Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES.
# SPDX-FileCopyrightText: NVIDIA CORPORATION & AFFILIATES
# Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
Expand All @@ -22,7 +23,28 @@ declare -r platform_json="/usr/share/sonic/device/$platform/platform.json"

declare -r query='.DPUS | to_entries[] | "\(.key) \(.value.bus_info)"'

# Kill any stale initramfs udevd that survived switch_root.
# During boot, the initramfs starts systemd-udevd before the overlayfs root is
# created. If device firmware init is slow (e.g. DPU FW timeout), udevd workers
# block and the initramfs cannot stop udevd before switch_root. The stale
# process ends up with a broken root filesystem view (its root still points to
# the initramfs rootfs, not the overlayfs). Writing udev rules below triggers
# the stale udevd to access file system for the updated rules which crashes
# because dir_fd_is_root() triggers assertion failure for a
# non-chrooted process in systemd.
kill_stale_udevd() {
local sysd_pid
sysd_pid=$(systemctl show systemd-udevd -p MainPID --value 2>/dev/null)
for pid in $(pgrep -f "systemd-udevd --daemon"); do
if [ "$pid" != "$sysd_pid" ]; then
logger "dpu-udev-manager: killing stale initramfs udevd PID $pid (systemd udevd is PID $sysd_pid)"
kill -9 "$pid" 2>/dev/null || true
fi
done
}

do_start() {
kill_stale_udevd
jq -r "$query" $platform_json | while read -r dpu bus_info; do
echo SUBSYSTEM==\"net\", ACTION==\"add\", KERNELS==\"$bus_info\", NAME=\"$dpu\"
done > $udev_file
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