Guilherme G. Piccoli 16fed31153 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 13:32:56 +01:00
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acpi	ACPI: APEI: Fix integer overflow in ghes_estatus_pool_init()	2022-10-13 20:40:09 +02:00
asm-generic	15 hotfixes. 11 marked cc:stable. Only three or four of the latter	2022-12-02 13:39:38 -08:00
clocksource
crypto
drm	drm/ttm: fix undefined behavior in bit shift for TTM_TT_FLAG_PRIV_POPULATED	2022-12-31 13:32:06 +01:00
dt-bindings	clk: imx: rename video_pll1 to video_pll	2022-12-31 13:32:16 +01:00
keys
kunit	kunit: declare kunit_assert structs as const	2022-10-07 10:19:18 -06:00
kvm
linux	video: hyperv_fb: Avoid taking busy spinlock on panic path	2022-12-31 13:32:56 +01:00
math-emu
media	media fixes for v6.1-rc2	2022-10-22 15:30:15 -07:00
memory
misc
net	ipvs: use u64_stats_t for the per-cpu counters	2022-12-31 13:32:26 +01:00
pcmcia
ras
rdma
rv
scsi	SCSI misc on 20221007	2022-10-07 12:33:18 -07:00
soc	ARM: at91: pm: avoid soft resetting AC DLL	2022-11-01 12:25:19 +02:00
sound	ALSA: pcm: fix undefined behavior in bit shift for SNDRV_PCM_RATE_KNOT	2022-12-31 13:32:14 +01:00
target
trace	IB/mad: Don't call to function that might sleep while in atomic context	2022-12-31 13:32:32 +01:00
uapi	dmaengine: idxd: Fix crc_val field for completion record	2022-12-31 13:32:49 +01:00
ufs	SCSI misc on 20221007	2022-10-07 12:33:18 -07:00
vdso
video
xen	xen/virtio: enable grant based virtio on x86	2022-10-10 14:31:26 +02:00