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authorDongmin Lee <ldmldm05@gmail.com>2023-11-04 20:33:20 +0900
committerAndrew Morton <akpm@linux-foundation.org>2023-12-10 17:21:25 -0800
commita9a1d6ad668f2ea0b5a77d0c4c7a41446d0801a8 (patch)
tree2bf6d83a2a49250ca19d2d996034b9329191a5cb /kernel/reboot.c
parent0c92218f4e7d4b4a7245d32bea042fa6f9cc39d7 (diff)
kernel/reboot: explicitly notify if halt occurred instead of power off
When kernel_can_power_off() returns false, and reboot has called with LINUX_REBOOT_CMD_POWER_OFF, kernel_halt() will be initiated instead of actual power off function. However, in this situation, Kernel never explicitly notifies user that system halted instead of requested power off. Since halt and power off perform different behavior, and user initiated reboot call with power off command, not halt, This could be unintended behavior to user, like this: ~ # poweroff -f [ 3.581482] reboot: System halted Therefore, this explicitly notifies user that poweroff is not available, and halting has been occured as an alternative behavior instead: ~ # poweroff -f [ 4.123668] reboot: Power off not available: System halted instead [akpm@linux-foundation.org: tweak comment text] Link: https://lkml.kernel.org/r/20231104113320.72440-1-ldmldm05@gmail.com Signed-off-by: Dongmin Lee <ldmldm05@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'kernel/reboot.c')
-rw-r--r--kernel/reboot.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 395a0ea3c7a8..c3a3b82c4f64 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -59,6 +59,14 @@ struct sys_off_handler {
};
/*
+ * This variable is used to indicate if a halt was initiated instead of a
+ * reboot when the reboot call was invoked with LINUX_REBOOT_CMD_POWER_OFF, but
+ * the system cannot be powered off. This allowes kernel_halt() to notify users
+ * of that.
+ */
+static bool poweroff_fallback_to_halt;
+
+/*
* Temporary stub that prevents linkage failure while we're in process
* of removing all uses of legacy pm_power_off() around the kernel.
*/
@@ -297,7 +305,10 @@ void kernel_halt(void)
kernel_shutdown_prepare(SYSTEM_HALT);
migrate_to_reboot_cpu();
syscore_shutdown();
- pr_emerg("System halted\n");
+ if (poweroff_fallback_to_halt)
+ pr_emerg("Power off not available: System halted instead\n");
+ else
+ pr_emerg("System halted\n");
kmsg_dump(KMSG_DUMP_SHUTDOWN);
machine_halt();
}
@@ -732,8 +743,10 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
/* Instead of trying to make the power_off code look like
* halt when pm_power_off is not set do it the easy way.
*/
- if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off())
+ if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off()) {
+ poweroff_fallback_to_halt = true;
cmd = LINUX_REBOOT_CMD_HALT;
+ }
mutex_lock(&system_transition_mutex);
switch (cmd) {