Messages in this thread | | | Subject | Re: [PATCH 1/1] debugfs: use IS_ERR to check for error | From | Christian König <> | Date | Fri, 3 Sep 2021 08:27:34 +0200 |
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Am 02.09.21 um 19:01 schrieb Das, Nirmoy: > > On 9/2/2021 6:34 PM, Greg KH wrote: >> On Thu, Sep 02, 2021 at 05:10:24PM +0200, Christian König wrote: >>> Am 02.09.21 um 14:20 schrieb Greg KH: >>>> On Thu, Sep 02, 2021 at 02:03:12PM +0200, Christian König wrote: >>>>> Am 02.09.21 um 12:38 schrieb Greg KH: >>>>>> On Thu, Sep 02, 2021 at 12:29:17PM +0200, Nirmoy Das wrote: >>>>>>> debugfs_create_file() returns encoded error so >>>>>>> use IS_ERR for checking return value. >>>>>>> >>>>>>> References: >>>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Famd%2F-%2Fissues%2F1686&data=04%7C01%7Cnirmoy.das%40amd.com%7C7a1f1095c0d64416576c08d96e2f7b38%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637661973378236086%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=g9BQRJG8gvjGFq6oj5vk9PCemQ39U19CLmkMNHVUafg%3D&reserved=0 >>>>>>> Signed-off-by: Nirmoy Das <nirmoy.das@amd.com> >>>>>>> --- >>>>>>> fs/debugfs/inode.c | 2 +- >>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c >>>>>>> index 8129a430d789..2f117c57160d 100644 >>>>>>> --- a/fs/debugfs/inode.c >>>>>>> +++ b/fs/debugfs/inode.c >>>>>>> @@ -528,7 +528,7 @@ void debugfs_create_file_size(const char >>>>>>> *name, umode_t mode, >>>>>>> { >>>>>>> struct dentry *de = debugfs_create_file(name, mode, >>>>>>> parent, data, fops); >>>>>>> - if (de) >>>>>>> + if (!IS_ERR(de)) >>>>>>> d_inode(de)->i_size = file_size; >>>>>>> } >>>>>>> EXPORT_SYMBOL_GPL(debugfs_create_file_size); >>>>>>> -- >>>>>>> 2.32.0 >>>>>>> >>>>>> Ah, good catch, I'll queue this up after 5.15-rc1 is out, thanks! >>>>> Thinking more about this if I'm not completely mistaken >>>>> debugfs_create_file() returns -ENODEV when debugfs is disabled and >>>>> NULL on >>>>> any other error. >>>> How can this function be called if debugfs is not enabled in the >>>> system >>>> configuration? This _is_ the debugfs core code. >>> Well, that's what I meant. The original code is correct and Nirmoy's >>> patch >>> here is breaking it. >> Ah, yes, sorry, you are right. This function can not return an error >> value, if something went wrong, the result will always be NULL. > > > I just realized that we don't return NULL on error anymore: > > commit ff9fb72bc07705c00795ca48631f7fffe24d2c6b > Author: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Date: Wed Jan 23 11:28:14 2019 +0100 > > debugfs: return error values, not NULL > > > and the current doc also says "If an error occurs, ERR_PTR(-ERROR) > will be returned." > > If I am not missing anything, this patch should be fine.
Ah! Yes, now that makes sense.
Looks like that my memory and the documentation under https://www.kernel.org/doc/htmldocs/filesystems/API-debugfs-create-file.html is outdated.
I can update my memory, but I have no idea where this documentation comes from and how to fix it.
Regards, Christian.
> > > Regards, > > Nirmoy > >> >>> Nirmoys other patch is for a driver and there the function can >>> indeed return >>> both error code and NULL. >> You should never be checking this stuff in a caller anyway, so no, don't >> do it there either. >> >> thanks, >> >> greg k-h
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