Files
linux-stable-mirror/include/linux
Guilherme G. Piccoli 659747f6f6 video: hyperv_fb: Avoid taking busy spinlock on panic path
[ Upstream commit 1d044ca035 ]

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>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220819221731.480795-10-gpiccoli@igalia.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:14:39 +01:00
..
2022-08-17 14:23:11 +02:00
2022-10-26 12:35:12 +02:00
2022-08-31 17:16:34 +02:00
2021-12-14 10:57:11 +01:00
2022-07-07 17:53:26 +02:00
2021-11-25 09:48:41 +01:00
2022-10-26 12:35:26 +02:00
2022-04-13 20:59:03 +02:00
2022-08-17 14:24:08 +02:00
2022-07-12 16:35:08 +02:00
2022-06-09 10:23:32 +02:00
2022-11-03 23:59:15 +09:00
2022-07-02 16:41:17 +02:00
2022-07-12 16:35:08 +02:00
2021-11-21 13:44:12 +01:00
2022-07-29 17:25:32 +02:00
2022-09-15 11:30:05 +02:00