[PATCH v4 05/25] reboot: Warn if restart handler has duplicated priority
From: Dmitry Osipenko <digetx@gmail.com>
Date: 2021-11-26 18:22:53
Also in:
linux-acpi, linux-m68k, linux-mips, linux-pm, linux-riscv, linux-sh, linux-tegra, lkml, xen-devel
Subsystem:
the rest · Maintainer:
Linus Torvalds
Add sanity check which ensures that there are no two restart handlers registered with the same priority. Normally it's a direct sign of a problem if two handlers use the same priority. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- kernel/reboot.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 6bcc5d6a6572..e6659ae329f1 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c@@ -182,7 +182,20 @@ static ATOMIC_NOTIFIER_HEAD(restart_handler_list); */ int register_restart_handler(struct notifier_block *nb) { - return atomic_notifier_chain_register(&restart_handler_list, nb); + int ret; + + ret = atomic_notifier_chain_register(&restart_handler_list, nb); + if (ret) + return ret; + + /* + * Handler must have unique priority. Otherwise call order is + * determined by registration order, which is unreliable. + */ + WARN(!atomic_notifier_has_unique_priority(&restart_handler_list, nb), + "restart handler must have unique priority\n"); + + return 0; } EXPORT_SYMBOL(register_restart_handler);
--
2.33.1