Re: [PATCH] KVM: Replace DEFINE_SIMPLE_ATTRIBUTE with DEFINE_DEBUGFS_ATTRIBUTE

[Paolo Bonzini]

On 01/02/21 09:38, Jiapeng Chong wrote:
Fix the following coccicheck warning:
./arch/x86/kvm/debugfs.c:44:0-23: WARNING: vcpu_tsc_scaling_frac_fops
should be defined with DEFINE_DEBUGFS_ATTRIBUTE.

./arch/x86/kvm/debugfs.c:36:0-23: WARNING: vcpu_tsc_scaling_fops should
be defined with DEFINE_DEBUGFS_ATTRIBUTE.

./arch/x86/kvm/debugfs.c:27:0-23: WARNING: vcpu_tsc_offset_fops should
be defined with DEFINE_DEBUGFS_ATTRIBUTE.

Reported-by: Abaci Robot <ab...@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.ch...@linux.alibaba.com>
---
  arch/x86/kvm/debugfs.c | 9 +++++----
  1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index 7e818d6..9c0e29e 100644
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -15,7 +15,7 @@ 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)
  {
@@ -24,7 +24,7 @@ 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)
  {
@@ -33,7 +33,7 @@ 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)
  {
@@ -41,7 +41,8 @@ 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");
  
  void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry)
  {


If you wanted to do this, you would have to use 
debugfs_create_file_unsafe() as well.

In practice, nobody does that because it's not a performance-sensitive 
path and it's not worth the maintenance cost of using a less safe API.

Paolo