From: John Ogness <john.ogness@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>, Petr Mladek <pmladek@suse.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
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Subject: Re: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path
Date: Tue, 10 May 2022 21:46:38 +0206 [thread overview]
Message-ID: <87h75xkwg9.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <20220510132015.38923cb2@gandalf.local.home>
On 2022-05-10, Steven Rostedt <rostedt@goodmis.org> wrote:
>> As already mentioned in the other reply, panic() sometimes stops the
>> other CPUs using NMI, for example, see kdump_nmi_shootdown_cpus().
>>
>> Another situation is when the CPU using the lock ends in some
>> infinite loop because something went wrong. The system is in
>> an unpredictable state during panic().
>>
>> I am not sure if this is possible with the code under gsmi_dev.lock
>> but such things really happen during panic() in other subsystems.
>> Using trylock in the panic() code path is a good practice.
>
> I believe that Peter Zijlstra had a special spin lock for NMIs or
> early printk, where it would not block if the lock was held on the
> same CPU. That is, if an NMI happened and paniced while this lock was
> held on the same CPU, it would not deadlock. But it would block if the
> lock was held on another CPU.
Yes. And starting with 5.19 it will be carrying the name that _you_ came
up with (cpu_sync):
printk_cpu_sync_get_irqsave()
printk_cpu_sync_put_irqrestore()
John
next prev parent reply other threads:[~2022-05-10 19:40 UTC|newest]
Thread overview: 183+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 22:48 [PATCH 00/30] The panic notifiers refactor Guilherme G. Piccoli
2022-04-27 22:48 ` [PATCH 01/30] x86/crash,reboot: Avoid re-disabling VMX in all CPUs on crash/restart Guilherme G. Piccoli
2022-05-09 12:32 ` Guilherme G. Piccoli
2022-05-09 15:52 ` Sean Christopherson
2022-05-10 20:11 ` Guilherme G. Piccoli
2022-04-27 22:48 ` [PATCH 02/30] ARM: kexec: Disable IRQs/FIQs also on crash CPUs shutdown path Guilherme G. Piccoli
2022-04-29 16:26 ` Michael Kelley (LINUX)
2022-04-29 18:20 ` Marc Zyngier
2022-04-29 21:38 ` Guilherme G. Piccoli
2022-04-29 21:45 ` Russell King (Oracle)
2022-04-29 21:56 ` Guilherme G. Piccoli
2022-04-29 22:00 ` Marc Zyngier
2022-04-27 22:48 ` [PATCH 03/30] notifier: Add panic notifiers info and purge trailing whitespaces Guilherme G. Piccoli
2022-04-27 22:48 ` [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path Guilherme G. Piccoli
2022-05-03 18:03 ` Evan Green
2022-05-03 19:12 ` Guilherme G. Piccoli
2022-05-03 21:56 ` Evan Green
2022-05-04 12:45 ` Guilherme G. Piccoli
2022-05-10 11:38 ` Petr Mladek
2022-05-10 13:04 ` Guilherme G. Piccoli
2022-05-10 17:20 ` Steven Rostedt
2022-05-10 19:40 ` John Ogness [this message]
2022-05-11 11:13 ` Petr Mladek
2022-04-27 22:48 ` [PATCH 05/30] misc/pvpanic: " Guilherme G. Piccoli
2022-05-10 12:14 ` Petr Mladek
2022-05-10 13:00 ` Guilherme G. Piccoli
2022-05-17 10:58 ` Petr Mladek
2022-05-17 13:03 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 06/30] soc: bcm: brcmstb: Document panic notifier action and remove useless header Guilherme G. Piccoli
2022-05-02 15:38 ` Florian Fainelli
2022-05-02 15:47 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 07/30] mips: ip22: Reword PANICED to PANICKED " Guilherme G. Piccoli
2022-05-04 20:32 ` Thomas Bogendoerfer
2022-05-04 21:26 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 08/30] powerpc/setup: Refactor/untangle panic notifiers Guilherme G. Piccoli
2022-05-05 18:55 ` Hari Bathini
2022-05-05 19:28 ` Guilherme G. Piccoli
2022-05-09 12:50 ` Guilherme G. Piccoli
2022-05-10 13:53 ` Michael Ellerman
2022-05-10 14:10 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex_trylock on panic notifier Guilherme G. Piccoli
2022-04-28 8:11 ` Suzuki K Poulose
2022-04-29 14:01 ` Guilherme G. Piccoli
2022-05-09 13:09 ` Guilherme G. Piccoli
2022-05-09 16:14 ` Suzuki K Poulose
2022-05-09 16:26 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 10/30] alpha: Clean-up the panic notifier code Guilherme G. Piccoli
2022-05-09 14:13 ` Guilherme G. Piccoli
2022-05-10 14:16 ` Petr Mladek
2022-05-11 20:10 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 11/30] um: Improve panic notifiers consistency and ordering Guilherme G. Piccoli
2022-04-28 8:30 ` Johannes Berg
2022-04-29 15:46 ` Guilherme G. Piccoli
2022-05-10 14:28 ` Petr Mladek
2022-05-11 20:22 ` Guilherme G. Piccoli
2022-05-13 14:44 ` Johannes Berg
2022-05-15 22:12 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 12/30] parisc: Replace regular spinlock with spin_trylock on panic path Guilherme G. Piccoli
2022-04-28 16:55 ` Helge Deller
2022-04-29 14:34 ` Guilherme G. Piccoli
2022-05-23 20:40 ` Guilherme G. Piccoli
2022-05-23 21:31 ` Helge Deller
2022-05-23 21:55 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 13/30] s390/consoles: Improve panic notifiers reliability Guilherme G. Piccoli
2022-04-29 18:46 ` Heiko Carstens
2022-04-29 19:31 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 14/30] panic: Properly identify the panic event to the notifiers' callbacks Guilherme G. Piccoli
2022-05-10 15:16 ` Petr Mladek
2022-05-10 16:16 ` Guilherme G. Piccoli
2022-05-17 13:11 ` Petr Mladek
2022-05-17 15:19 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 15/30] bus: brcmstb_gisb: Clean-up panic/die notifiers Guilherme G. Piccoli
2022-05-02 15:38 ` Florian Fainelli
2022-05-02 15:50 ` Guilherme G. Piccoli
2022-05-10 15:28 ` Petr Mladek
2022-05-17 15:32 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 16/30] drivers/hv/vmbus, video/hyperv_fb: Untangle and refactor Hyper-V panic notifiers Guilherme G. Piccoli
2022-04-29 17:16 ` Michael Kelley (LINUX)
2022-04-29 22:35 ` Guilherme G. Piccoli
2022-05-03 18:13 ` Michael Kelley (LINUX)
2022-05-03 18:57 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 17/30] tracing: Improve panic/die notifiers Guilherme G. Piccoli
2022-04-29 9:22 ` Sergei Shtylyov
2022-04-29 13:23 ` Steven Rostedt
2022-04-29 13:46 ` Guilherme G. Piccoli
2022-04-29 13:56 ` Steven Rostedt
2022-04-29 14:44 ` Guilherme G. Piccoli
2022-05-11 11:45 ` Petr Mladek
2022-05-17 15:33 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 18/30] notifier: Show function names on notifier routines if DEBUG_NOTIFIERS is set Guilherme G. Piccoli
2022-04-28 1:01 ` Xiaoming Ni
2022-04-29 19:38 ` Guilherme G. Piccoli
2022-05-10 17:29 ` Steven Rostedt
2022-05-16 16:14 ` Guilherme G. Piccoli
2022-04-29 16:27 ` Michael Kelley (LINUX)
2022-04-27 22:49 ` [PATCH 19/30] panic: Add the panic hypervisor notifier list Guilherme G. Piccoli
2022-04-29 17:30 ` Michael Kelley (LINUX)
2022-04-29 18:04 ` Guilherme G. Piccoli
2022-05-03 17:44 ` Michael Kelley (LINUX)
2022-05-03 17:56 ` Guilherme G. Piccoli
2022-05-16 14:01 ` Petr Mladek
2022-05-16 15:06 ` Guilherme G. Piccoli
2022-05-16 16:02 ` Evan Green
2022-05-17 13:28 ` Petr Mladek
2022-05-17 16:37 ` Guilherme G. Piccoli
2022-05-18 7:33 ` Petr Mladek
2022-05-18 13:24 ` Guilherme G. Piccoli
2022-05-17 13:57 ` Petr Mladek
2022-05-17 16:42 ` Guilherme G. Piccoli
2022-05-18 7:38 ` Petr Mladek
2022-05-18 13:09 ` Guilherme G. Piccoli
2022-05-18 22:17 ` Scott Branden
2022-05-19 12:19 ` Guilherme G. Piccoli
2022-05-19 19:20 ` Scott Branden
2022-05-23 14:56 ` Guilherme G. Piccoli
2022-05-24 8:04 ` Petr Mladek
2022-05-18 7:58 ` Petr Mladek
2022-05-18 13:16 ` Guilherme G. Piccoli
2022-05-19 7:03 ` Petr Mladek
2022-05-19 12:07 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 20/30] panic: Add the panic informational " Guilherme G. Piccoli
2022-04-27 23:49 ` Paul E. McKenney
2022-04-28 8:14 ` Suzuki K Poulose
2022-04-29 14:50 ` Guilherme G. Piccoli
2022-05-16 14:11 ` Petr Mladek
2022-05-16 14:28 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 21/30] panic: Introduce the panic pre-reboot " Guilherme G. Piccoli
2022-04-28 14:13 ` Alex Elder
2022-04-28 16:26 ` Corey Minyard
2022-04-29 15:18 ` Guilherme G. Piccoli
2022-04-29 16:04 ` Max Filippov
2022-04-29 19:34 ` Guilherme G. Piccoli
2022-05-16 14:33 ` Petr Mladek
2022-05-16 16:05 ` Guilherme G. Piccoli
2022-05-16 16:18 ` Luck, Tony
2022-05-16 16:33 ` Guilherme G. Piccoli
2022-05-17 14:11 ` Petr Mladek
2022-05-17 16:45 ` Guilherme G. Piccoli
2022-05-17 17:02 ` Luck, Tony
2022-05-17 18:12 ` Guilherme G. Piccoli
2022-05-17 19:07 ` Luck, Tony
2022-04-27 22:49 ` [PATCH 22/30] panic: Introduce the panic post-reboot " Guilherme G. Piccoli
2022-05-09 14:16 ` Guilherme G. Piccoli
2022-05-11 16:45 ` Heiko Carstens
2022-05-11 19:58 ` Guilherme G. Piccoli
2022-05-16 14:45 ` Petr Mladek
2022-05-16 16:08 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 23/30] printk: kmsg_dump: Introduce helper to inform number of dumpers Guilherme G. Piccoli
2022-05-10 17:40 ` Steven Rostedt
2022-05-11 20:03 ` Guilherme G. Piccoli
2022-05-16 14:50 ` Petr Mladek
2022-05-16 16:09 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 24/30] panic: Refactor the panic path Guilherme G. Piccoli
2022-04-28 0:28 ` Randy Dunlap
2022-04-29 16:04 ` Guilherme G. Piccoli
2022-05-09 14:25 ` Guilherme G. Piccoli
2022-04-29 17:53 ` Michael Kelley (LINUX)
2022-04-29 20:38 ` Guilherme G. Piccoli
2022-05-03 17:31 ` Michael Kelley (LINUX)
2022-05-03 18:06 ` Guilherme G. Piccoli
2022-05-09 15:16 ` d.hatayama
2022-05-09 16:39 ` Guilherme G. Piccoli
2022-05-12 14:03 ` Petr Mladek
2022-05-15 22:47 ` Guilherme G. Piccoli
2022-05-16 10:21 ` Petr Mladek
2022-05-16 16:32 ` Guilherme G. Piccoli
2022-05-19 23:45 ` Baoquan He
2022-05-20 11:23 ` Guilherme G. Piccoli
2022-05-24 8:01 ` Petr Mladek
2022-05-24 10:18 ` Baoquan He
2022-05-24 8:32 ` Baoquan He
2022-05-24 14:44 ` Eric W. Biederman
2022-05-26 16:25 ` Guilherme G. Piccoli
2022-06-14 14:36 ` Petr Mladek
2022-06-15 9:36 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 25/30] panic, printk: Add console flush parameter and convert panic_print to a notifier Guilherme G. Piccoli
2022-05-16 14:56 ` Petr Mladek
2022-05-16 16:11 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 26/30] Drivers: hv: Do not force all panic notifiers to execute before kdump Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 27/30] powerpc: " Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 28/30] panic: Unexport crash_kexec_post_notifiers Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 29/30] powerpc: ps3, pseries: Avoid duplicate call to kmsg_dump() on panic Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 30/30] um: Avoid duplicate call to kmsg_dump() Guilherme G. Piccoli
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