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x86/hyperv: Remove unregister syscore call from Hyper-V cleanup

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Hyper-V cleanup code comes under panic path where preemption and irq
is already disabled. So calling of unregister_syscore_ops might schedule
out the thread even for the case where mutex lock is free.
hyperv_cleanup
	unregister_syscore_ops
			mutex_lock(&syscore_ops_lock)
				might_sleep
Here might_sleep might schedule out this thread, where voluntary preemption
config is on and this thread will never comes back. And also this was added
earlier to maintain the symmetry which is not required as this can comes
during crash shutdown path only.

To prevent the same, removing unregister_syscore_ops function call.

Signed-off-by: Gaurav Kohli <gauravkohli@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1669443291-2575-1-git-send-email-gauravkohli@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Gaurav Kohli 2022-11-25 22:14:51 -08:00 committed by Wei Liu
parent fea858dc5d
commit 32c97d980e
1 changed files with 0 additions and 2 deletions
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2
arch/x86/hyperv/hv_init.c
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@ -537,8 +537,6 @@ void hyperv_cleanup(void)
union hv_x64_msr_hypercall_contents hypercall_msr;
union hv_reference_tsc_msr tsc_msr;
unregister_syscore_ops(&hv_syscore_ops);
/* Reset our OS id */
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);