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Message-Id: <20220719195325.402745-10-gpiccoli@igalia.com> Date: Tue, 19 Jul 2022 16:53:22 -0300 From: "Guilherme G. Piccoli" <gpiccoli@...lia.com> To: akpm@...ux-foundation.org, bhe@...hat.com, pmladek@...e.com, kexec@...ts.infradead.org Cc: linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org, netdev@...r.kernel.org, x86@...nel.org, kernel-dev@...lia.com, kernel@...ccoli.net, halves@...onical.com, fabiomirmar@...il.com, alejandro.j.jimenez@...cle.com, andriy.shevchenko@...ux.intel.com, arnd@...db.de, bp@...en8.de, corbet@....net, d.hatayama@...fujitsu.com, dave.hansen@...ux.intel.com, dyoung@...hat.com, feng.tang@...el.com, gregkh@...uxfoundation.org, mikelley@...rosoft.com, hidehiro.kawai.ez@...achi.com, jgross@...e.com, john.ogness@...utronix.de, keescook@...omium.org, luto@...nel.org, mhiramat@...nel.org, mingo@...hat.com, paulmck@...nel.org, peterz@...radead.org, rostedt@...dmis.org, senozhatsky@...omium.org, stern@...land.harvard.edu, tglx@...utronix.de, vgoyal@...hat.com, vkuznets@...hat.com, will@...nel.org, "Guilherme G. Piccoli" <gpiccoli@...lia.com>, Arjan van de Ven <arjan@...ux.intel.com>, Cong Wang <xiyou.wangcong@...il.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Valentin Schneider <valentin.schneider@....com>, Xiaoming Ni <nixiaoming@...wei.com> Subject: [PATCH v2 09/13] notifier: Show function names on notifier routines if DEBUG_NOTIFIERS is set 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@...ux.intel.com> Cc: Cong Wang <xiyou.wangcong@...il.com> Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de> Cc: Steven Rostedt <rostedt@...dmis.org> Cc: Valentin Schneider <valentin.schneider@....com> Cc: Xiaoming Ni <nixiaoming@...wei.com> Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.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
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