linux-kernel - Re: [PATCH v1 2/5] KVM: s390: remove unneeded srcu lock

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Message-ID: <0cffcc15-1e75-4d6c-92d8-dd0158c912ba@de.ibm.com>
Date: Mon, 19 May 2025 10:25:01 +0200
From: Christian Borntraeger <borntraeger@...ibm.com>
To: Claudio Imbrenda <imbrenda@...ux.ibm.com>, linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org, linux-s390@...r.kernel.org, frankja@...ux.ibm.com,
        seiden@...ux.ibm.com, nsg@...ux.ibm.com, nrb@...ux.ibm.com,
        david@...hat.com, hca@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v1 2/5] KVM: s390: remove unneeded srcu lock

Am 14.05.25 um 18:38 schrieb Claudio Imbrenda:
> All paths leading to handle_essa() already hold the kvm->srcu.
You could add
since commit 800c1065c320 ("KVM: s390: Lock kvm->srcu at the appropriate places").

> Remove unneeded srcu locking from handle_essa().
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>

Reviewed-by: Christian Borntraeger <borntraeger@...ux.ibm.com>



> ---
>   arch/s390/kvm/priv.c | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
> index 1a49b89706f8..758cefb5bac7 100644
> --- a/arch/s390/kvm/priv.c
> +++ b/arch/s390/kvm/priv.c
> @@ -1297,12 +1297,8 @@ static int handle_essa(struct kvm_vcpu *vcpu)
>   		/* Retry the ESSA instruction */
>   		kvm_s390_retry_instr(vcpu);
>   	} else {
> -		int srcu_idx;
> -
>   		mmap_read_lock(vcpu->kvm->mm);
> -		srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
>   		i = __do_essa(vcpu, orc);
> -		srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
>   		mmap_read_unlock(vcpu->kvm->mm);
>   		if (i < 0)
>   			return i;