From b7124bbd6a89fd517039e88a4c1193286cdbeee5 Mon Sep 17 00:00:00 2001
From: Zach Dykstra <dykstra.zachary@gmail.com>
Date: Wed, 1 May 2024 09:01:54 -0500
Subject: [PATCH] contrib: add megaraid_sas unbind script

---
 contrib/README.md            |  4 ++++
 contrib/megaraid-teardown.sh | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100755 contrib/megaraid-teardown.sh

diff --git a/contrib/README.md b/contrib/README.md
index d873d98d1..82a3438ee 100644
--- a/contrib/README.md
+++ b/contrib/README.md
@@ -28,6 +28,10 @@ review the scripts themselves for more thorough descriptions of their use.
   early-setup hook, this facilitates, *e.g.*, multiple-slot keys for ZFS pools
   that use native encryption.
 
+- `megaraid-teardown.sh` - Unbind drivers for `megaraid_sas` devices, so that
+  they're available after a kexec. This is patterned after the XHCI teardown
+  script.
+
 - `remote-ssh-build.sh` - This is a standalone script intended to wrap the
   `zbm-builder.sh` image-builder script, incorporating a dropbear SSH server,
   host keys and an `authorized_keys` file that permit remote access and pool
diff --git a/contrib/megaraid-teardown.sh b/contrib/megaraid-teardown.sh
new file mode 100755
index 000000000..b6087b105
--- /dev/null
+++ b/contrib/megaraid-teardown.sh
@@ -0,0 +1,17 @@
+#!/bin/bash
+
+#
+# Configure this script as a user teardown.d hook
+#
+
+SYS_MEGARAID=/sys/bus/pci/drivers/megaraid_sas
+
+# shellcheck disable=SC2231
+for DEVPATH in ${SYS_MEGARAID}/????:??:??.?; do
+        [ -L "${DEVPATH}" ] || continue
+        DEVICE="${DEVPATH#"${SYS_MEGARAID}"/}"
+        echo "Tearing down Megaraid controller ${DEVICE}..."
+        echo "${DEVICE}" > ${SYS_MEGARAID}/unbind
+        echo "Resetting Megaraid controller ${DEVICE}..."
+        echo "1" > /sys/bus/pci/devices/${DEVICE}/reset
+done