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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
commitf4cdf7ca9a1fdcca413157df19753f388a5a224e (patch)
tree60a31895b2446cd7fa27514e8c2843534a0de0da /drivers/char/hangcheck-timer.c
downloadlinux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz
linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ...
Diffstat (limited to 'drivers/char/hangcheck-timer.c')
-rw-r--r--drivers/char/hangcheck-timer.c179
1 files changed, 179 insertions, 0 deletions
diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c
new file mode 100644
index 000000000..231cbf7b3
--- /dev/null
+++ b/drivers/char/hangcheck-timer.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * hangcheck-timer.c
+ *
+ * Driver for a little io fencing timer.
+ *
+ * Copyright (C) 2002, 2003 Oracle. All rights reserved.
+ *
+ * Author: Joel Becker <joel.becker@oracle.com>
+ */
+
+/*
+ * The hangcheck-timer driver uses the TSC to catch delays that
+ * jiffies does not notice. A timer is set. When the timer fires, it
+ * checks whether it was delayed and if that delay exceeds a given
+ * margin of error. The hangcheck_tick module parameter takes the timer
+ * duration in seconds. The hangcheck_margin parameter defines the
+ * margin of error, in seconds. The defaults are 60 seconds for the
+ * timer and 180 seconds for the margin of error. IOW, a timer is set
+ * for 60 seconds. When the timer fires, the callback checks the
+ * actual duration that the timer waited. If the duration exceeds the
+ * allotted time and margin (here 60 + 180, or 240 seconds), the machine
+ * is restarted. A healthy machine will have the duration match the
+ * expected timeout very closely.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/uaccess.h>
+#include <linux/sysrq.h>
+#include <linux/timer.h>
+#include <linux/hrtimer.h>
+
+#define VERSION_STR "0.9.1"
+
+#define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */
+#define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */
+
+static int hangcheck_tick = DEFAULT_IOFENCE_TICK;
+static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN;
+static int hangcheck_reboot; /* Defaults to not reboot */
+static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */
+
+/* options - modular */
+module_param(hangcheck_tick, int, 0);
+MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
+module_param(hangcheck_margin, int, 0);
+MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
+module_param(hangcheck_reboot, int, 0);
+MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
+module_param(hangcheck_dump_tasks, int, 0);
+MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(VERSION_STR);
+
+/* options - nonmodular */
+#ifndef MODULE
+
+static int __init hangcheck_parse_tick(char *str)
+{
+ int par;
+
+ if (get_option(&str, &par))
+ hangcheck_tick = par;
+ return 1;
+}
+
+static int __init hangcheck_parse_margin(char *str)
+{
+ int par;
+
+ if (get_option(&str, &par))
+ hangcheck_margin = par;
+ return 1;
+}
+
+static int __init hangcheck_parse_reboot(char *str)
+{
+ int par;
+
+ if (get_option(&str, &par))
+ hangcheck_reboot = par;
+ return 1;
+}
+
+static int __init hangcheck_parse_dump_tasks(char *str)
+{
+ int par;
+
+ if (get_option(&str, &par))
+ hangcheck_dump_tasks = par;
+ return 1;
+}
+
+__setup("hcheck_tick", hangcheck_parse_tick);
+__setup("hcheck_margin", hangcheck_parse_margin);
+__setup("hcheck_reboot", hangcheck_parse_reboot);
+__setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks);
+#endif /* not MODULE */
+
+#define TIMER_FREQ 1000000000ULL
+
+/* Last time scheduled */
+static unsigned long long hangcheck_tsc, hangcheck_tsc_margin;
+
+static void hangcheck_fire(struct timer_list *);
+
+static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire);
+
+static void hangcheck_fire(struct timer_list *unused)
+{
+ unsigned long long cur_tsc, tsc_diff;
+
+ cur_tsc = ktime_get_ns();
+
+ if (cur_tsc > hangcheck_tsc)
+ tsc_diff = cur_tsc - hangcheck_tsc;
+ else
+ tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */
+
+ if (tsc_diff > hangcheck_tsc_margin) {
+ if (hangcheck_dump_tasks) {
+ pr_crit("Hangcheck: Task state:\n");
+#ifdef CONFIG_MAGIC_SYSRQ
+ handle_sysrq('t');
+#endif /* CONFIG_MAGIC_SYSRQ */
+ }
+ if (hangcheck_reboot) {
+ pr_crit("Hangcheck: hangcheck is restarting the machine.\n");
+ emergency_restart();
+ } else {
+ pr_crit("Hangcheck: hangcheck value past margin!\n");
+ }
+ }
+#if 0
+ /*
+ * Enable to investigate delays in detail
+ */
+ pr_debug("Hangcheck: called %lld ns since last time (%lld ns overshoot)\n",
+ tsc_diff, tsc_diff - hangcheck_tick*TIMER_FREQ);
+#endif
+ mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
+ hangcheck_tsc = ktime_get_ns();
+}
+
+
+static int __init hangcheck_init(void)
+{
+ pr_debug("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
+ VERSION_STR, hangcheck_tick, hangcheck_margin);
+ hangcheck_tsc_margin =
+ (unsigned long long)hangcheck_margin + hangcheck_tick;
+ hangcheck_tsc_margin *= TIMER_FREQ;
+
+ hangcheck_tsc = ktime_get_ns();
+ mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
+
+ return 0;
+}
+
+
+static void __exit hangcheck_exit(void)
+{
+ timer_delete_sync(&hangcheck_ticktock);
+ pr_debug("Hangcheck: Stopped hangcheck timer.\n");
+}
+
+module_init(hangcheck_init);
+module_exit(hangcheck_exit);