mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-15 07:26:45 +07:00
87dffe86d4
When guest receives a sysrq request from the host it acknowledges it by writing '\0' to control/sysrq xenstore node. This, however, make xenstore watch fire again but xenbus_scanf() fails to parse empty value with "%c" format string: sysrq: SysRq : Emergency Sync Emergency Sync complete xen:manage: Error -34 reading sysrq code in control/sysrq Ignore -ERANGE the same way we already ignore -ENOENT, empty value in control/sysrq is totally legal. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
389 lines
8.2 KiB
C
389 lines
8.2 KiB
C
/*
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* Handle extern requests for shutdown, reboot and sysrq
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*/
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#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/reboot.h>
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#include <linux/sysrq.h>
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#include <linux/stop_machine.h>
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#include <linux/freezer.h>
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#include <linux/syscore_ops.h>
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#include <linux/export.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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#include <xen/grant_table.h>
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#include <xen/events.h>
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#include <xen/hvc-console.h>
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#include <xen/page.h>
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#include <xen/xen-ops.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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enum shutdown_state {
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SHUTDOWN_INVALID = -1,
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SHUTDOWN_POWEROFF = 0,
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SHUTDOWN_SUSPEND = 2,
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/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
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report a crash, not be instructed to crash!
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HALT is the same as POWEROFF, as far as we're concerned. The tools use
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the distinction when we return the reason code to them. */
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SHUTDOWN_HALT = 4,
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};
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/* Ignore multiple shutdown requests. */
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static enum shutdown_state shutting_down = SHUTDOWN_INVALID;
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struct suspend_info {
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int cancelled;
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};
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static RAW_NOTIFIER_HEAD(xen_resume_notifier);
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void xen_resume_notifier_register(struct notifier_block *nb)
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{
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raw_notifier_chain_register(&xen_resume_notifier, nb);
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}
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EXPORT_SYMBOL_GPL(xen_resume_notifier_register);
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void xen_resume_notifier_unregister(struct notifier_block *nb)
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{
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raw_notifier_chain_unregister(&xen_resume_notifier, nb);
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}
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EXPORT_SYMBOL_GPL(xen_resume_notifier_unregister);
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#ifdef CONFIG_HIBERNATE_CALLBACKS
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static int xen_suspend(void *data)
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{
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struct suspend_info *si = data;
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int err;
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BUG_ON(!irqs_disabled());
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err = syscore_suspend();
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if (err) {
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pr_err("%s: system core suspend failed: %d\n", __func__, err);
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return err;
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}
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gnttab_suspend();
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xen_manage_runstate_time(-1);
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xen_arch_pre_suspend();
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si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
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? virt_to_gfn(xen_start_info)
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: 0);
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xen_arch_post_suspend(si->cancelled);
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xen_manage_runstate_time(si->cancelled ? 1 : 0);
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gnttab_resume();
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if (!si->cancelled) {
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xen_irq_resume();
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xen_timer_resume();
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}
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syscore_resume();
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return 0;
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}
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static void do_suspend(void)
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{
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int err;
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struct suspend_info si;
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shutting_down = SHUTDOWN_SUSPEND;
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err = freeze_processes();
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if (err) {
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pr_err("%s: freeze processes failed %d\n", __func__, err);
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goto out;
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}
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err = freeze_kernel_threads();
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if (err) {
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pr_err("%s: freeze kernel threads failed %d\n", __func__, err);
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goto out_thaw;
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}
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err = dpm_suspend_start(PMSG_FREEZE);
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if (err) {
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pr_err("%s: dpm_suspend_start %d\n", __func__, err);
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goto out_thaw;
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}
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printk(KERN_DEBUG "suspending xenstore...\n");
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xs_suspend();
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err = dpm_suspend_end(PMSG_FREEZE);
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if (err) {
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pr_err("dpm_suspend_end failed: %d\n", err);
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si.cancelled = 0;
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goto out_resume;
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}
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xen_arch_suspend();
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si.cancelled = 1;
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err = stop_machine(xen_suspend, &si, cpumask_of(0));
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/* Resume console as early as possible. */
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if (!si.cancelled)
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xen_console_resume();
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raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);
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dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
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if (err) {
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pr_err("failed to start xen_suspend: %d\n", err);
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si.cancelled = 1;
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}
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xen_arch_resume();
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out_resume:
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if (!si.cancelled)
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xs_resume();
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else
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xs_suspend_cancel();
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dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
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out_thaw:
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thaw_processes();
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out:
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shutting_down = SHUTDOWN_INVALID;
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}
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#endif /* CONFIG_HIBERNATE_CALLBACKS */
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struct shutdown_handler {
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#define SHUTDOWN_CMD_SIZE 11
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const char command[SHUTDOWN_CMD_SIZE];
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bool flag;
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void (*cb)(void);
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};
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static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
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{
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switch (code) {
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case SYS_DOWN:
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case SYS_HALT:
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case SYS_POWER_OFF:
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shutting_down = SHUTDOWN_POWEROFF;
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default:
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break;
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}
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return NOTIFY_DONE;
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}
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static void do_poweroff(void)
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{
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switch (system_state) {
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case SYSTEM_BOOTING:
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case SYSTEM_SCHEDULING:
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orderly_poweroff(true);
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break;
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case SYSTEM_RUNNING:
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orderly_poweroff(false);
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break;
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default:
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/* Don't do it when we are halting/rebooting. */
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pr_info("Ignoring Xen toolstack shutdown.\n");
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break;
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}
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}
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static void do_reboot(void)
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{
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shutting_down = SHUTDOWN_POWEROFF; /* ? */
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ctrl_alt_del();
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}
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static struct shutdown_handler shutdown_handlers[] = {
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{ "poweroff", true, do_poweroff },
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{ "halt", false, do_poweroff },
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{ "reboot", true, do_reboot },
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#ifdef CONFIG_HIBERNATE_CALLBACKS
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{ "suspend", true, do_suspend },
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#endif
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};
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static void shutdown_handler(struct xenbus_watch *watch,
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const char *path, const char *token)
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{
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char *str;
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struct xenbus_transaction xbt;
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int err;
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int idx;
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if (shutting_down != SHUTDOWN_INVALID)
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return;
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again:
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err = xenbus_transaction_start(&xbt);
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if (err)
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return;
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str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
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/* Ignore read errors and empty reads. */
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if (XENBUS_IS_ERR_READ(str)) {
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xenbus_transaction_end(xbt, 1);
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return;
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}
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for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
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if (strcmp(str, shutdown_handlers[idx].command) == 0)
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break;
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}
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/* Only acknowledge commands which we are prepared to handle. */
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if (idx < ARRAY_SIZE(shutdown_handlers))
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xenbus_write(xbt, "control", "shutdown", "");
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err = xenbus_transaction_end(xbt, 0);
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if (err == -EAGAIN) {
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kfree(str);
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goto again;
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}
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if (idx < ARRAY_SIZE(shutdown_handlers)) {
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shutdown_handlers[idx].cb();
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} else {
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pr_info("Ignoring shutdown request: %s\n", str);
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shutting_down = SHUTDOWN_INVALID;
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}
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kfree(str);
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}
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#ifdef CONFIG_MAGIC_SYSRQ
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static void sysrq_handler(struct xenbus_watch *watch, const char *path,
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const char *token)
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{
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char sysrq_key = '\0';
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struct xenbus_transaction xbt;
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int err;
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again:
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err = xenbus_transaction_start(&xbt);
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if (err)
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return;
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err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
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if (err < 0) {
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/*
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* The Xenstore watch fires directly after registering it and
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* after a suspend/resume cycle. So ENOENT is no error but
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* might happen in those cases. ERANGE is observed when we get
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* an empty value (''), this happens when we acknowledge the
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* request by writing '\0' below.
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*/
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if (err != -ENOENT && err != -ERANGE)
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pr_err("Error %d reading sysrq code in control/sysrq\n",
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err);
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xenbus_transaction_end(xbt, 1);
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return;
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}
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if (sysrq_key != '\0') {
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err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
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if (err) {
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pr_err("%s: Error %d writing sysrq in control/sysrq\n",
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__func__, err);
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xenbus_transaction_end(xbt, 1);
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return;
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}
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}
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err = xenbus_transaction_end(xbt, 0);
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if (err == -EAGAIN)
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goto again;
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if (sysrq_key != '\0')
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handle_sysrq(sysrq_key);
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}
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static struct xenbus_watch sysrq_watch = {
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.node = "control/sysrq",
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.callback = sysrq_handler
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};
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#endif
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static struct xenbus_watch shutdown_watch = {
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.node = "control/shutdown",
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.callback = shutdown_handler
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};
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static struct notifier_block xen_reboot_nb = {
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.notifier_call = poweroff_nb,
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};
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static int setup_shutdown_watcher(void)
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{
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int err;
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int idx;
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#define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
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char node[FEATURE_PATH_SIZE];
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err = register_xenbus_watch(&shutdown_watch);
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if (err) {
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pr_err("Failed to set shutdown watcher\n");
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return err;
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}
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#ifdef CONFIG_MAGIC_SYSRQ
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err = register_xenbus_watch(&sysrq_watch);
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if (err) {
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pr_err("Failed to set sysrq watcher\n");
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return err;
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}
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#endif
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for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
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if (!shutdown_handlers[idx].flag)
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continue;
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snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
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shutdown_handlers[idx].command);
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err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
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if (err) {
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pr_err("%s: Error %d writing %s\n", __func__,
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err, node);
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return err;
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}
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}
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return 0;
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}
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static int shutdown_event(struct notifier_block *notifier,
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unsigned long event,
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void *data)
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{
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setup_shutdown_watcher();
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return NOTIFY_DONE;
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}
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int xen_setup_shutdown_event(void)
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{
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static struct notifier_block xenstore_notifier = {
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.notifier_call = shutdown_event
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};
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if (!xen_domain())
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return -ENODEV;
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register_xenstore_notifier(&xenstore_notifier);
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register_reboot_notifier(&xen_reboot_nb);
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return 0;
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}
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EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
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subsys_initcall(xen_setup_shutdown_event);
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