* [PATCH linux-next] KVM:define vcpu_get_pid_fops with DEFINE_DEBUGFS_ATTRIBUTE
@ 2022-08-15 3:12 cgel.zte
2022-09-08 17:39 ` Sean Christopherson
0 siblings, 1 reply; 2+ messages in thread
From: cgel.zte @ 2022-08-15 3:12 UTC (permalink / raw)
To: pbonzini; +Cc: kvm, linux-kernel, ye xingchen, Zeal Robot
From: ye xingchen <ye.xingchen@zte.com.cn>
From the coccinelle check:
./virt/kvm/kvm_main.c line 3847
WARNING vcpu_get_pid_fops should be defined with DEFINE_DEBUGFS_ATTRIBUTE
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
---
virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 515dfe9d3bcf..a0817179f8e4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3844,7 +3844,7 @@ static int vcpu_get_pid(void *data, u64 *val)
return 0;
}
-DEFINE_SIMPLE_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
+DEFINE_DEBUGFS_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
static void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
{
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH linux-next] KVM:define vcpu_get_pid_fops with DEFINE_DEBUGFS_ATTRIBUTE
2022-08-15 3:12 [PATCH linux-next] KVM:define vcpu_get_pid_fops with DEFINE_DEBUGFS_ATTRIBUTE cgel.zte
@ 2022-09-08 17:39 ` Sean Christopherson
0 siblings, 0 replies; 2+ messages in thread
From: Sean Christopherson @ 2022-09-08 17:39 UTC (permalink / raw)
To: cgel.zte; +Cc: pbonzini, kvm, linux-kernel, ye xingchen, Zeal Robot
On Mon, Aug 15, 2022, cgel.zte@gmail.com wrote:
> From: ye xingchen <ye.xingchen@zte.com.cn>
>
> From the coccinelle check:
> ./virt/kvm/kvm_main.c line 3847
> WARNING vcpu_get_pid_fops should be defined with DEFINE_DEBUGFS_ATTRIBUTE
>
> Reported-by: Zeal Robot <zealci@zte.com.cn>
> Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
> ---
> virt/kvm/kvm_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 515dfe9d3bcf..a0817179f8e4 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3844,7 +3844,7 @@ static int vcpu_get_pid(void *data, u64 *val)
> return 0;
> }
>
> -DEFINE_SIMPLE_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
Based on the comments in scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci,
it seems that using DEFINE_DEBUGFS_ATTRIBUTE is only beneficial if the file is
created with debugfs_create_file_unsafe(). IIUC, using DEFINE_DEBUGFS_ATTRIBUTE
without switching to debugfs_create_file_unsafe() will actually _add_ overhead.
//# Rationale: DEFINE_SIMPLE_ATTRIBUTE + debugfs_create_file()
//# imposes some significant overhead as compared to
//# DEFINE_DEBUGFS_ATTRIBUTE + debugfs_create_file_unsafe().
Using DEFINE_DEBUGFS_ATTRIBUTE also effectively drops ->llseek() support. I assume
that's not a problem? But someone that knows how this is actually used should
chime in.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-08-15 3:12 [PATCH linux-next] KVM:define vcpu_get_pid_fops with DEFINE_DEBUGFS_ATTRIBUTE cgel.zte
2022-09-08 17:39 ` Sean Christopherson
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