[v1] x86/itmt: Don't make ITMT enablement depend on debugfs

[PATCH] x86/itmt: Don't make ITMT enablement depend on debugfs

Posted by Mario Limonciello 1 month, 2 weeks ago

sched_set_itmt_support() treats debugfs file creation failures as fatal.
When CONFIG_DEBUG_FS is disabled, debugfs stubs return ERR_PTR(-ENODEV),
causing ITMT to be silently disabled.

debugfs is a debug-only facility; its return values should be ignored.
Drop the fatal error handling and enable ITMT unconditionally.

Fixes: d04013a4b21b ("x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs")
Reported-by: Klaus Kusche <klaus.kusche@computerix.info>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 arch/x86/kernel/itmt.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c
index 243a769fdd97b..85ebde361d6ae 100644
--- a/arch/x86/kernel/itmt.c
+++ b/arch/x86/kernel/itmt.c
@@ -110,18 +110,14 @@ int sched_set_itmt_support(void)
 						    arch_debugfs_dir,
 						    &sysctl_sched_itmt_enabled,
 						    &dfs_sched_itmt_fops);
-	if (IS_ERR_OR_NULL(dfs_sched_itmt)) {
+	if (IS_ERR(dfs_sched_itmt))
 		dfs_sched_itmt = NULL;
-		return -ENOMEM;
-	}
 
 	dfs_sched_core_prio = debugfs_create_file("sched_core_priority", 0644,
 						  arch_debugfs_dir, NULL,
 						  &sched_core_priority_fops);
-	if (IS_ERR_OR_NULL(dfs_sched_core_prio)) {
+	if (IS_ERR(dfs_sched_core_prio))
 		dfs_sched_core_prio = NULL;
-		return -ENOMEM;
-	}
 
 	sched_itmt_capable = true;
 
-- 
2.43.0

Re: [PATCH] x86/itmt: Don't make ITMT enablement depend on debugfs

Posted by K Prateek Nayak 1 month, 2 weeks ago

Hello Mario,

On 8/11/2026 8:06 PM, Mario Limonciello wrote:
> sched_set_itmt_support() treats debugfs file creation failures as fatal.
> When CONFIG_DEBUG_FS is disabled, debugfs stubs return ERR_PTR(-ENODEV),
> causing ITMT to be silently disabled.
> 
> debugfs is a debug-only facility; its return values should be ignored.
> Drop the fatal error handling and enable ITMT unconditionally.
> 
> Fixes: d04013a4b21b ("x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs")
> Reported-by: Klaus Kusche <klaus.kusche@computerix.info>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Feel free to include:

Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>

> ---
>  arch/x86/kernel/itmt.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c
> index 243a769fdd97b..85ebde361d6ae 100644
> --- a/arch/x86/kernel/itmt.c
> +++ b/arch/x86/kernel/itmt.c
> @@ -110,18 +110,14 @@ int sched_set_itmt_support(void)
>  						    arch_debugfs_dir,
>  						    &sysctl_sched_itmt_enabled,
>  						    &dfs_sched_itmt_fops);
> -	if (IS_ERR_OR_NULL(dfs_sched_itmt)) {
> +	if (IS_ERR(dfs_sched_itmt))
>  		dfs_sched_itmt = NULL;
> -		return -ENOMEM;
> -	}
>  
>  	dfs_sched_core_prio = debugfs_create_file("sched_core_priority", 0644,
>  						  arch_debugfs_dir, NULL,
>  						  &sched_core_priority_fops);
> -	if (IS_ERR_OR_NULL(dfs_sched_core_prio)) {
> +	if (IS_ERR(dfs_sched_core_prio))
>  		dfs_sched_core_prio = NULL;
> -		return -ENOMEM;
> -	}
>  
>  	sched_itmt_capable = true;
>  

-- 
Thanks and Regards,
Prateek