Messages in this thread Patch in this message | | | From | "Guilherme G. Piccoli" <> | Subject | [PATCH v2 09/13] notifier: Show function names on notifier routines if DEBUG_NOTIFIERS is set | Date | Tue, 19 Jul 2022 16:53:22 -0300 |
| |
Currently we have a debug infrastructure in the notifiers file, but it's very simple/limited. Extend it by:
(a) Showing all registered/unregistered notifiers' callback names;
(b) Adding a dynamic debug tuning to allow showing called notifiers' function names. Notice that this should be guarded as a tunable since it can flood the kernel log buffer.
Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Valentin Schneider <valentin.schneider@arm.com> Cc: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
---
V2: - Major improvement thanks to the great idea from Xiaoming - changed all the ksym wheel reinvention to printk %ps modifier;
- Instead of ifdefs, using IS_ENABLED() - thanks Steven.
- Removed an unlikely() hint on debug path.
kernel/notifier.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/kernel/notifier.c b/kernel/notifier.c index 0d5bd62c480e..350761b34f8a 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -37,6 +37,10 @@ static int notifier_chain_register(struct notifier_block **nl, } n->next = *nl; rcu_assign_pointer(*nl, n); + + if (IS_ENABLED(CONFIG_DEBUG_NOTIFIERS)) + pr_info("notifiers: registered %ps\n", n->notifier_call); + return 0; } @@ -46,6 +50,11 @@ static int notifier_chain_unregister(struct notifier_block **nl, while ((*nl) != NULL) { if ((*nl) == n) { rcu_assign_pointer(*nl, n->next); + + if (IS_ENABLED(CONFIG_DEBUG_NOTIFIERS)) + pr_info("notifiers: unregistered %ps\n", + n->notifier_call); + return 0; } nl = &((*nl)->next); @@ -77,13 +86,14 @@ static int notifier_call_chain(struct notifier_block **nl, while (nb && nr_to_call) { next_nb = rcu_dereference_raw(nb->next); -#ifdef CONFIG_DEBUG_NOTIFIERS - if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) { - WARN(1, "Invalid notifier called!"); - nb = next_nb; - continue; + if (IS_ENABLED(CONFIG_DEBUG_NOTIFIERS)) { + if (!func_ptr_is_kernel_text(nb->notifier_call)) { + WARN(1, "Invalid notifier called!"); + nb = next_nb; + continue; + } + pr_debug("notifiers: calling %ps\n", nb->notifier_call); } -#endif ret = nb->notifier_call(nb, val, v); if (nr_calls) -- 2.37.1
| |