[PATCH] x86/intel_rdt: fix rdt_mount error handling

[PATCH] x86/intel_rdt: fix rdt_mount error handling

[Arnd Bergmann]

The newly introduced rdt_mount function returns an unintialized
pointer if rdtgroup_create_info_dir() fails:

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c: In function ‘rdt_mount’:
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c:710:9: error: ‘dentry’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

Clearly the intention was to propagate the error code here as we
do in the other failure cases.

Fixes: 5ff193fbde20 ("x86/intel_rdt: Add basic resctrl filesystem support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index a90ad22b9823..e66c7a58505e 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -691,8 +691,10 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
 	closid_init();
 
 	ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
-	if (ret)
+	if (ret) {
+		dentry = ERR_PTR(ret);
 		goto out_cdp;
+	}
 
 	dentry = kernfs_mount(fs_type, flags, rdt_root,
 			      RDTGROUP_SUPER_MAGIC, NULL);
-- 
2.9.0

Re: [PATCH] x86/intel_rdt: fix rdt_mount error handling

[Thomas Gleixner]

On Tue, 8 Nov 2016, Arnd Bergmann wrote:

> The newly introduced rdt_mount function returns an unintialized
> pointer if rdtgroup_create_info_dir() fails:

http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=x86/cache&id=7bff0af51012500718971f9cc3485f67252353eb

RE: [PATCH] x86/intel_rdt: fix rdt_mount error handling

[Yu, Fenghua]

> From: Arnd Bergmann [mailto:arnd@arndb.de]
> The newly introduced rdt_mount function returns an unintialized pointer if
> rdtgroup_create_info_dir() fails:
> 
> arch/x86/kernel/cpu/intel_rdt_rdtgroup.c: In function ‘rdt_mount’:
> arch/x86/kernel/cpu/intel_rdt_rdtgroup.c:710:9: error: ‘dentry’ may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
> 
> Clearly the intention was to propagate the error code here as we do in the
> other failure cases.
> 
> Fixes: 5ff193fbde20 ("x86/intel_rdt: Add basic resctrl filesystem support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> index a90ad22b9823..e66c7a58505e 100644
> --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
> @@ -691,8 +691,10 @@ static struct dentry *rdt_mount(struct
> file_system_type *fs_type,
>  	closid_init();
> 
>  	ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
> -	if (ret)
> +	if (ret) {
> +		dentry = ERR_PTR(ret);
>  		goto out_cdp;
> +	}
> 
>  	dentry = kernfs_mount(fs_type, flags, rdt_root,
>  			      RDTGROUP_SUPER_MAGIC, NULL);

The warning has been fixed and pushed in tip tree already:
http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=x86/cache&id=7bff0af51012500718971f9cc3485f67252353eb

Thanks.

-Fenghua