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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> |
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| .. | ||
| backlight | ||
| console | ||
| fbdev | ||
| logo | ||
| aperture.c | ||
| display_timing.c | ||
| hdmi.c | ||
| Kconfig | ||
| Makefile | ||
| of_display_timing.c | ||
| of_videomode.c | ||
| vgastate.c | ||
| videomode.c | ||