From: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
To: linux-hyperv@vger.kernel.org, mikelley@microsoft.com
Cc: kexec@lists.infradead.org, pmladek@suse.com, bhe@redhat.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com,
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alejandro.j.jimenez@oracle.com,
andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de,
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dave.hansen@linux.intel.com, dyoung@redhat.com,
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john.ogness@linutronix.de, keescook@chromium.org,
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paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org,
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tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com,
will@kernel.org, xuqiang36@huawei.com,
Andrea Parri <parri.andrea@gmail.com>,
Dexuan Cui <decui@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
Wei Liu <wei.liu@kernel.org>
Subject: Re: [PATCH V3 09/11] video/hyperv_fb: Avoid taking busy spinlock on panic path
Date: Sun, 18 Sep 2022 11:12:15 -0300 [thread overview]
Message-ID: <89f8fb2d-3f39-4591-190c-f134c4c173a6@igalia.com> (raw)
In-Reply-To: <20220819221731.480795-10-gpiccoli@igalia.com>
On 19/08/2022 19:17, Guilherme G. Piccoli wrote:
> The Hyper-V framebuffer code registers a panic notifier in order
> to try updating its fbdev if the kernel crashed. The notifier
> callback is straightforward, but it calls the vmbus_sendpacket()
> routine eventually, and such function takes a spinlock for the
> ring buffer operations.
>
> Panic path runs in atomic context, with local interrupts and
> preemption disabled, and all secondary CPUs shutdown. That said,
> taking a spinlock might cause a lockup if a secondary CPU was
> disabled with such lock taken. Fix it here by checking if the
> ring buffer spinlock is busy on Hyper-V framebuffer panic notifier;
> if so, bail-out avoiding the potential lockup scenario.
>
> Cc: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> Cc: Dexuan Cui <decui@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Michael Kelley <mikelley@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Cc: Tianyu Lan <Tianyu.Lan@microsoft.com>
> Cc: Wei Liu <wei.liu@kernel.org>
> Tested-by: Fabio A M Martins <fabiomirmar@gmail.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
>
> ---
>
> V3:
> - simplified the code based on Michael's suggestion - thanks!
>
> V2:
> - new patch, based on the discussion in [0].
> [0] https://lore.kernel.org/lkml/2787b476-6366-1c83-db80-0393da417497@igalia.com/
>
>
> drivers/hv/ring_buffer.c | 13 +++++++++++++
> drivers/video/fbdev/hyperv_fb.c | 8 +++++++-
> include/linux/hyperv.h | 2 ++
> 3 files changed, 22 insertions(+), 1 deletion(-)
> [...]
Hi Michael, apologies for the ping.
Any reviews/comments on this one are greatly appreciated!
Cheers,
Guilherme
next prev parent reply other threads:[~2022-09-18 14:12 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 22:17 [PATCH V3 00/11] The panic notifiers refactor - fixes/clean-ups (V3) Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 01/11] ARM: Disable FIQs (but not IRQs) on CPUs shutdown paths Guilherme G. Piccoli
2022-09-18 13:58 ` Guilherme G. Piccoli
2022-10-17 14:00 ` Guilherme G. Piccoli
2022-10-17 14:17 ` Russell King (Oracle)
2022-10-17 14:50 ` Guilherme G. Piccoli
2022-10-17 17:47 ` Russell King (Oracle)
2022-10-17 19:43 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 02/11] notifier: Add panic notifiers info and purge trailing whitespaces Guilherme G. Piccoli
2022-11-22 13:19 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 03/11] alpha: Clean-up the panic notifier code Guilherme G. Piccoli
2022-11-22 13:22 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 04/11] um: Improve panic notifiers consistency and ordering Guilherme G. Piccoli
2022-09-18 14:00 ` Guilherme G. Piccoli
2022-09-18 21:19 ` Richard Weinberger
2022-09-19 11:44 ` Guilherme G. Piccoli
2022-10-17 14:01 ` Guilherme G. Piccoli
2022-10-17 14:10 ` Richard Weinberger
2022-10-17 14:22 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 05/11] parisc: Replace regular spinlock with spin_trylock on panic path Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 06/11] tracing: Improve panic/die notifiers Guilherme G. Piccoli
2022-09-18 14:04 ` Guilherme G. Piccoli
2022-10-17 14:02 ` Guilherme G. Piccoli
2022-10-20 21:29 ` Steven Rostedt
2022-10-20 21:53 ` Guilherme G. Piccoli
2022-10-20 22:22 ` Steven Rostedt
2022-10-20 22:37 ` Guilherme G. Piccoli
2022-11-22 13:27 ` Guilherme G. Piccoli
2022-12-13 23:51 ` Guilherme G. Piccoli
2022-12-14 0:06 ` Steven Rostedt
2022-12-14 0:52 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 07/11] notifiers: Add tracepoints to the notifiers infrastructure Guilherme G. Piccoli
2022-09-18 14:07 ` Guilherme G. Piccoli
2022-10-17 14:04 ` Guilherme G. Piccoli
2022-11-22 13:30 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 08/11] EDAC/altera: Skip the panic notifier if kdump is loaded Guilherme G. Piccoli
2022-09-18 14:10 ` Guilherme G. Piccoli
2022-10-17 14:05 ` Guilherme G. Piccoli
2022-11-22 13:33 ` Guilherme G. Piccoli
2022-11-22 15:06 ` Borislav Petkov
2023-02-10 16:01 ` Guilherme G. Piccoli
2022-12-09 16:03 ` Petr Mladek
2022-08-19 22:17 ` [PATCH V3 09/11] video/hyperv_fb: Avoid taking busy spinlock on panic path Guilherme G. Piccoli
2022-09-18 14:12 ` Guilherme G. Piccoli [this message]
2022-10-04 16:17 ` Michael Kelley (LINUX)
2022-08-19 22:17 ` [PATCH V3 10/11] drivers/hv/vmbus, video/hyperv_fb: Untangle and refactor Hyper-V panic notifiers Guilherme G. Piccoli
2022-10-04 16:24 ` Michael Kelley (LINUX)
2022-10-04 17:20 ` Guilherme G. Piccoli
2022-10-17 15:26 ` Michael Kelley (LINUX)
2022-11-10 21:32 ` Guilherme G. Piccoli
2022-11-11 22:47 ` Wei Liu
2022-11-11 23:16 ` Wei Liu
2022-11-12 21:53 ` Guilherme G. Piccoli
2022-08-19 22:17 ` [PATCH V3 11/11] panic: Fixes the panic_print NMI backtrace setting Guilherme G. Piccoli
2022-09-18 14:13 ` Guilherme G. Piccoli
2022-11-22 13:35 ` Guilherme G. Piccoli
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