From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Guilherme G. Piccoli" Subject: [PATCH 17/30] tracing: Improve panic/die notifiers Date: Wed, 27 Apr 2022 19:49:11 -0300 Message-ID: <20220427224924.592546-18-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hLU6FYhfxLVdoWtAQufGAEn/Zsr+kiR9XIIa4KTweDg=; b=FI16AKY5WsZvSG U5ojlwAzO9fzaqEndooOe81DtRlPoKaq1l0ONsTiZkclr33Coq+HuapEYmPXSvO3h14h49zDGz0AP wncXlr2k43txINfkPmIPU/9/YPdAV8OgumR58VDs/OQUUCww1YBSSNq94xSkHbxVZdfyma87z6iTw 39U38wsGzUug5DJvzh7f/LXfrNE6+6i1cRNTNS7C0UW2fEaY8y6l21INa89XlVshXnObbbgg3UxsS PALQnloYWM9dCqwyYxlcPz/X1N1Zydwd7RF1Awesjnbg+cAKzwcbw7ipdZatbur4JX5UCaO/LlL+C QZ4d6IQzC2p2C+oO/ZbA==; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=gwBR7P38mmxeEI4wWnwfuOo3Vx6Wo8buxtIoJ+/ueVE=; b=nwXMrZImrRof6aT4nflSriZWm8 nV+2kfTnZMr3qMfu/pdKx8zdoFC6dPSZfgjMR8nrCqKQx0a9STr9zXRmf603LSCMYxoe/0rzj8WAX X04mzyflhbAneN3N3eqd1bEuJEgnFV2TubG1LTS2zdwee0DTxDCCfkp/jZLLefrxcRie9zAR6UkMF CbBI0mU22IJBGJ0ER3H7bHP1OaQk7bRcIVlpHROO0rfL6uLx6VUv9a0aPf+94uNbhp5w7FYgnWnfd FC3cJ2sUp+UEhn1teUMFvXk88fY0u++AP/ytEp5+rJzALI+oR2Quq3NLCvwKLKxi/cwHyaoyY3uHg LhfKC/tQ==; In-Reply-To: <20220427224924.592546-1-gpiccoli@igalia.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+glud-user-mode-linux-devel=m.gmane-mx.org@lists.infradead.org To: akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, coresight@lists.linaro.org, linuxppc-dev@lists.ozlabs.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-leds@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-pm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, netdev@vger.kernel.org, openipmi-developer@lists.sourceforge.net, rcu@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernel-dev@igalia.com, gpiccoli@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8. Currently the tracing dump_on_oops feature is implemented through separate notifiers, one for die/oops and the other for panic. With the addition of panic notifier "id", this patch makes use of such "id" to unify both functions. It also comments the function and changes the priority of the notifier blocks, in order they run early compared to other notifiers, to prevent useless trace data (like the callback names for the other notifiers). Finally, we also removed an unnecessary header inclusion. Signed-off-by: Guilherme G. Piccoli --- kernel/trace/trace.c | 57 +++++++++++++++++++++++++------------------- 1 file changed, 32 insertions(+), 25 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index f4de111fa18f..c1d8a3622ccc 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -19,7 +19,6 @@ #include #include #include -#include #include #include #include @@ -9767,38 +9766,46 @@ static __init int tracer_init_tracefs(void) fs_initcall(tracer_init_tracefs); -static int trace_panic_handler(struct notifier_block *this, - unsigned long event, void *unused) +/* + * The idea is to execute the following die/panic callback early, in order + * to avoid showing irrelevant information in the trace (like other panic + * notifier functions); we are the 2nd to run, after hung_task/rcu_stall + * warnings get disabled (to prevent potential log flooding). + */ +static int trace_die_panic_handler(struct notifier_block *self, + unsigned long ev, void *unused) { - if (ftrace_dump_on_oops) + int do_dump; + + if (!ftrace_dump_on_oops) + return NOTIFY_DONE; + + switch (ev) { + case DIE_OOPS: + do_dump = 1; + break; + case PANIC_NOTIFIER: + do_dump = 1; + break; + default: + do_dump = 0; + break; + } + + if (do_dump) ftrace_dump(ftrace_dump_on_oops); - return NOTIFY_OK; + + return NOTIFY_DONE; } static struct notifier_block trace_panic_notifier = { - .notifier_call = trace_panic_handler, - .next = NULL, - .priority = 150 /* priority: INT_MAX >= x >= 0 */ + .notifier_call = trace_die_panic_handler, + .priority = INT_MAX - 1, }; -static int trace_die_handler(struct notifier_block *self, - unsigned long val, - void *data) -{ - switch (val) { - case DIE_OOPS: - if (ftrace_dump_on_oops) - ftrace_dump(ftrace_dump_on_oops); - break; - default: - break; - } - return NOTIFY_OK; -} - static struct notifier_block trace_die_notifier = { - .notifier_call = trace_die_handler, - .priority = 200 + .notifier_call = trace_die_panic_handler, + .priority = INT_MAX - 1, }; /* -- 2.36.0