powerpc/cell/axon_msi: replace DEFINE_SIMPLE_ATTRIBUTE with DEFINE_DEBUGFS_ATTRIBUTE

[PATCH linux-next] powerpc/cell/axon_msi: replace DEFINE_SIMPLE_ATTRIBUTE with DEFINE_DEBUGFS_ATTRIBUTE

Posted by zhang.songyi@zte.com.cn 3 years, 4 months ago

From: zhang songyi <zhang.songyi@zte.com.cn>

Fix the following coccicheck warning:
/arch/powerpc/platforms/cell/axon_msi.c:457:0-23: WARNING:
fops_msic should be defined with DEFINE_DEBUGFS_ATTRIBUTE

Signed-off-by: zhang songyi <zhang.songyi@zte.com.cn>
---
 arch/powerpc/platforms/cell/axon_msi.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/cell/axon_msi.c b/arch/powerpc/platforms/cell/axon_msi.c
index 5b012abca773..ab080b5022ff 100644
--- a/arch/powerpc/platforms/cell/axon_msi.c
+++ b/arch/powerpc/platforms/cell/axon_msi.c
@@ -454,7 +454,7 @@ static int msic_get(void *data, u64 *val)
        return 0;
 }

-DEFINE_SIMPLE_ATTRIBUTE(fops_msic, msic_get, msic_set, "%llu\n");
+DEFINE_DEBUGFS_ATTRIBUTE(fops_msic, msic_get, msic_set, "%llu\n");

 void axon_msi_debug_setup(struct device_node *dn, struct axon_msic *msic)
 {
@@ -475,6 +475,7 @@ void axon_msi_debug_setup(struct device_node *dn, struct axon_msic *msic)

        snprintf(name, sizeof(name), "msic_%d", of_node_to_nid(dn));

-       debugfs_create_file(name, 0600, arch_debugfs_dir, msic, &fops_msic);
+       debugfs_create_file_unsafe(name, 0600, arch_debugfs_dir,
+                                  msic, &fops_msic);
 }
 #endif /* DEBUG */
--
2.15.2

Re: [PATCH linux-next] powerpc/cell/axon_msi: replace DEFINE_SIMPLE_ATTRIBUTE with DEFINE_DEBUGFS_ATTRIBUTE

Posted by Christophe Leroy 3 years, 4 months ago

Hi,

Le 23/11/2022 à 10:06, zhang.songyi@zte.com.cn a écrit :
> From: zhang songyi <zhang.songyi@zte.com.cn>
> 
> Fix the following coccicheck warning:
> /arch/powerpc/platforms/cell/axon_msi.c:457:0-23: WARNING:
> fops_msic should be defined with DEFINE_DEBUGFS_ATTRIBUTE

What's the difference between this new patch and the one that is already 
awaiting application here : 
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20211222090655.484551-1-deng.changcheng@zte.com.cn/ 
?

The only difference I see it that the already existing patch has a more 
complete description of the change, so unless I'm missing something it 
would be nice to avoid sending the same changes again and again.

Thanks
Christophe



> 
> Signed-off-by: zhang songyi <zhang.songyi@zte.com.cn>
> ---
>   arch/powerpc/platforms/cell/axon_msi.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/cell/axon_msi.c b/arch/powerpc/platforms/cell/axon_msi.c
> index 5b012abca773..ab080b5022ff 100644
> --- a/arch/powerpc/platforms/cell/axon_msi.c
> +++ b/arch/powerpc/platforms/cell/axon_msi.c
> @@ -454,7 +454,7 @@ static int msic_get(void *data, u64 *val)
>          return 0;
>   }
> 
> -DEFINE_SIMPLE_ATTRIBUTE(fops_msic, msic_get, msic_set, "%llu\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(fops_msic, msic_get, msic_set, "%llu\n");
> 
>   void axon_msi_debug_setup(struct device_node *dn, struct axon_msic *msic)
>   {
> @@ -475,6 +475,7 @@ void axon_msi_debug_setup(struct device_node *dn, struct axon_msic *msic)
> 
>          snprintf(name, sizeof(name), "msic_%d", of_node_to_nid(dn));
> 
> -       debugfs_create_file(name, 0600, arch_debugfs_dir, msic, &fops_msic);
> +       debugfs_create_file_unsafe(name, 0600, arch_debugfs_dir,
> +                                  msic, &fops_msic);
>   }
>   #endif /* DEBUG */
> --
> 2.15.2

Re: [PATCH linux-next] powerpc/cell/axon_msi: replace DEFINE_SIMPLE_ATTRIBUTE with DEFINE_DEBUGFS_ATTRIBUTE

Posted by Michael Ellerman 3 years, 4 months ago

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Hi,
>
> Le 23/11/2022 à 10:06, zhang.songyi@zte.com.cn a écrit :
>> From: zhang songyi <zhang.songyi@zte.com.cn>
>> 
>> Fix the following coccicheck warning:
>> /arch/powerpc/platforms/cell/axon_msi.c:457:0-23: WARNING:
>> fops_msic should be defined with DEFINE_DEBUGFS_ATTRIBUTE
>
> What's the difference between this new patch and the one that is already 
> awaiting application here : 
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20211222090655.484551-1-deng.changcheng@zte.com.cn/ 
> ?
>
> The only difference I see it that the already existing patch has a more 
> complete description of the change, so unless I'm missing something it 
> would be nice to avoid sending the same changes again and again.

Both patches switch the code to use a function called "unsafe" without
adequately explaining why that is OK.

The commit that added the cocci check script says:

  If the original struct file_operations are known to be safe against removal
  races by themselves already, the proxy creation may be bypassed by creating
  the files through debugfs_create_file_unsafe().

None of these conversion patches ever contain any explanation which
speaks to that.

In this case I *think* the change is OK and there is no race because the
debugfs file is never removed. But I really wish the submitter would
tell me that in the change log.

cheers