Re: [PATCH v2 1/4] platform/x86/amd/hsmp: Use mutex to synchronize ACPI based probe

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Wed, 23 Jul 2025, Suma Hegde wrote:

> The hsmp_acpi_probe() function is called for each socket. When
> asynchronous probing is enabled, it can lead to race conditions
> due to multiple probes accessing shared data (hsmp_pdev->sock
> and the hsmp_pdev->is_probed variable), which may cause potential
> issues.
> 
> To resolve these issues, a guard mutex has been introduced to ensure
> synchronized execution.
> 
> Suggested-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Suma Hegde <suma.hegde@amd.com>
> Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>

I guess Fixes tag would be in order for this and some other patches in 
the series too.

-- 
 i.

> ---
> Changes since v1:
> 1. Guard the remove() also
> 2. Update commit description
> 
>  drivers/platform/x86/amd/hsmp/acpi.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
> index d974c2289f5a..b981ae3157ea 100644
> --- a/drivers/platform/x86/amd/hsmp/acpi.c
> +++ b/drivers/platform/x86/amd/hsmp/acpi.c
> @@ -13,6 +13,7 @@
>  
>  #include <linux/acpi.h>
>  #include <linux/array_size.h>
> +#include <linux/cleanup.h>
>  #include <linux/bits.h>
>  #include <linux/bitfield.h>
>  #include <linux/device.h>
> @@ -20,6 +21,7 @@
>  #include <linux/ioport.h>
>  #include <linux/kstrtox.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/platform_device.h>
>  #include <linux/sysfs.h>
>  #include <linux/uuid.h>
> @@ -44,6 +46,8 @@ struct hsmp_sys_attr {
>  	u32 msg_id;
>  };
>  
> +static DEFINE_MUTEX(hsmp_lock);
> +
>  static int amd_hsmp_acpi_rdwr(struct hsmp_socket *sock, u32 offset,
>  			      u32 *value, bool write)
>  {
> @@ -584,6 +588,7 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
>  	hsmp_pdev = get_hsmp_pdev();
>  	if (!hsmp_pdev)
>  		return -ENOMEM;
> +	guard(mutex)(&hsmp_lock);
>  
>  	if (!hsmp_pdev->is_probed) {
>  		hsmp_pdev->num_sockets = amd_num_nodes();
> @@ -620,6 +625,7 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
>  
>  static void hsmp_acpi_remove(struct platform_device *pdev)
>  {
> +	guard(mutex)(&hsmp_lock);
>  	/*
>  	 * We register only one misc_device even on multi-socket system.
>  	 * So, deregister should happen only once.
>