linux-kernel - Re: [PATCH] kvm: x86: Use DEFINE_DEBUGFS

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Date:   Tue, 17 Sep 2019 19:18:33 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yi Wang <wang.yi59@....com.cn>
Cc:     rkrcmar@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, xue.zhihong@....com.cn,
        up2wing@...il.com, wang.liang82@....com.cn,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] kvm: x86: Use DEFINE_DEBUGFS_ATTRIBUTE for debugfs files

On 22/07/19 09:33, Yi Wang wrote:
> We got these coccinelle warning:
> ./arch/x86/kvm/debugfs.c:23:0-23: WARNING: vcpu_timer_advance_ns_fops
> should be defined with DEFINE_DEBUGFS_ATTRIBUTE
> ./arch/x86/kvm/debugfs.c:32:0-23: WARNING: vcpu_tsc_offset_fops should
> be defined with DEFINE_DEBUGFS_ATTRIBUTE
> ./arch/x86/kvm/debugfs.c:41:0-23: WARNING: vcpu_tsc_scaling_fops should
> be defined with DEFINE_DEBUGFS_ATTRIBUTE
> ./arch/x86/kvm/debugfs.c:49:0-23: WARNING: vcpu_tsc_scaling_frac_fops
> should be defined with DEFINE_DEBUGFS_ATTRIBUTE
> 
> Use DEFINE_DEBUGFS_ATTRIBUTE() rather than DEFINE_SIMPLE_ATTRIBUTE()
> to fix this.
> 
> Signed-off-by: Yi Wang <wang.yi59@....com.cn>

It sucks though that you have to use a function with "unsafe" in the name.

Greg, is the patch doing the right thing?

Paolo

> ---
>  arch/x86/kvm/debugfs.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
> index 329361b..24016fb 100644
> --- a/arch/x86/kvm/debugfs.c
> +++ b/arch/x86/kvm/debugfs.c
> @@ -20,7 +20,7 @@ static int vcpu_get_timer_advance_ns(void *data, u64 *val)
>  	return 0;
>  }
>  
> -DEFINE_SIMPLE_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n");
>  
>  static int vcpu_get_tsc_offset(void *data, u64 *val)
>  {
> @@ -29,7 +29,7 @@ static int vcpu_get_tsc_offset(void *data, u64 *val)
>  	return 0;
>  }
>  
> -DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_offset_fops, vcpu_get_tsc_offset, NULL, "%lld\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(vcpu_tsc_offset_fops, vcpu_get_tsc_offset, NULL, "%lld\n");
>  
>  static int vcpu_get_tsc_scaling_ratio(void *data, u64 *val)
>  {
> @@ -38,7 +38,7 @@ static int vcpu_get_tsc_scaling_ratio(void *data, u64 *val)
>  	return 0;
>  }
>  
> -DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_scaling_fops, vcpu_get_tsc_scaling_ratio, NULL, "%llu\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(vcpu_tsc_scaling_fops, vcpu_get_tsc_scaling_ratio, NULL, "%llu\n");
>  
>  static int vcpu_get_tsc_scaling_frac_bits(void *data, u64 *val)
>  {
> @@ -46,20 +46,20 @@ static int vcpu_get_tsc_scaling_frac_bits(void *data, u64 *val)
>  	return 0;
>  }
>  
> -DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_scaling_frac_fops, vcpu_get_tsc_scaling_frac_bits, NULL, "%llu\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(vcpu_tsc_scaling_frac_fops, vcpu_get_tsc_scaling_frac_bits, NULL, "%llu\n");
>  
>  int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
>  {
>  	struct dentry *ret;
>  
> -	ret = debugfs_create_file("tsc-offset", 0444,
> +	ret = debugfs_create_file_unsafe("tsc-offset", 0444,
>  							vcpu->debugfs_dentry,
>  							vcpu, &vcpu_tsc_offset_fops);
>  	if (!ret)
>  		return -ENOMEM;
>  
>  	if (lapic_in_kernel(vcpu)) {
> -		ret = debugfs_create_file("lapic_timer_advance_ns", 0444,
> +		ret = debugfs_create_file_unsafe("lapic_timer_advance_ns", 0444,
>  								vcpu->debugfs_dentry,
>  								vcpu, &vcpu_timer_advance_ns_fops);
>  		if (!ret)
> @@ -67,12 +67,12 @@ int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
>  	}
>  
>  	if (kvm_has_tsc_control) {
> -		ret = debugfs_create_file("tsc-scaling-ratio", 0444,
> +		ret = debugfs_create_file_unsafe("tsc-scaling-ratio", 0444,
>  							vcpu->debugfs_dentry,
>  							vcpu, &vcpu_tsc_scaling_fops);
>  		if (!ret)
>  			return -ENOMEM;
> -		ret = debugfs_create_file("tsc-scaling-ratio-frac-bits", 0444,
> +		ret = debugfs_create_file_unsafe("tsc-scaling-ratio-frac-bits", 0444,
>  							vcpu->debugfs_dentry,
>  							vcpu, &vcpu_tsc_scaling_frac_fops);
>  		if (!ret)
>