Re: [Intel-gfx] [RFC] drm/hdcp: optimizing the srm handling

2020-01-22 Thread Sean Paul
On Tue, Jan 21, 2020 at 12:39:55PM +0530, Ramalingam C wrote:
> As we are not using the sysfs infrastructure anymore, link to it is
> removed. And global srm data and mutex to protect it are removed,
> with required handling at revocation check function.
> 

Hi Ram,
Thanks for taking this on. A few comments below..

> Yet to test hence RFC tag is added.
> 
> Signed-off-by: Ramalingam C 
> Suggested-by: Sean Paul 
> ---
>  drivers/gpu/drm/drm_hdcp.c | 68 ++
>  drivers/gpu/drm/drm_internal.h |  4 --
>  drivers/gpu/drm/drm_sysfs.c|  2 -
>  3 files changed, 27 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c
> index 9191633a3c43..cc08d953eb53 100644
> --- a/drivers/gpu/drm/drm_hdcp.c
> +++ b/drivers/gpu/drm/drm_hdcp.c
> @@ -23,13 +23,10 @@
>  
>  #include "drm_internal.h"
>  
> -static struct hdcp_srm {
> +struct hdcp_srm {

struct drm_hdcp_srm

would be more consistent with the rest of the subsystem

>   u32 revoked_ksv_cnt;
>   u8 *revoked_ksv_list;
> -
> - /* Mutex to protect above struct member */
> - struct mutex mutex;
> -} *srm_data;
> +};
>  
>  static inline void drm_hdcp_print_ksv(const u8 *ksv)
>  {
> @@ -91,7 +88,8 @@ static inline u32 get_vrl_length(const u8 *buf)
>   return drm_hdcp_be24_to_cpu(buf);
>  }
>  
> -static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count)
> +static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count,
> + struct hdcp_srm *srm_data)

Usually the drm structs are the first argument.

>  {
>   struct hdcp_srm_header *header;
>   u32 vrl_length, ksv_count;
> @@ -153,7 +151,8 @@ static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t 
> count)
>   return count;
>  }
>  
> -static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count)
> +static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count,
> + struct hdcp_srm *srm_data)
>  {
>   struct hdcp_srm_header *header;
>   u32 vrl_length, ksv_count, ksv_sz;
> @@ -226,18 +225,20 @@ static inline bool is_srm_version_hdcp2(const u8 *buf)
>   return *buf == (u8)(DRM_HDCP_2_SRM_ID << 4 | DRM_HDCP_2_INDICATOR);
>  }
>  
> -static void drm_hdcp_srm_update(const u8 *buf, size_t count)
> +static void drm_hdcp_srm_update(const u8 *buf, size_t count,
> + struct hdcp_srm *srm_data)
>  {
>   if (count < sizeof(struct hdcp_srm_header))
>   return;
>  
>   if (is_srm_version_hdcp1(buf))
> - drm_hdcp_parse_hdcp1_srm(buf, count);
> + drm_hdcp_parse_hdcp1_srm(buf, count, srm_data);
>   else if (is_srm_version_hdcp2(buf))
> - drm_hdcp_parse_hdcp2_srm(buf, count);
> + drm_hdcp_parse_hdcp2_srm(buf, count, srm_data);
>  }
>  
> -static void drm_hdcp_request_srm(struct drm_device *drm_dev)
> +static void drm_hdcp_request_srm(struct drm_device *drm_dev,
> +  struct hdcp_srm *srm_data)
>  {
>   char fw_name[36] = "display_hdcp_srm.bin";
>   const struct firmware *fw;
> @@ -250,7 +251,7 @@ static void drm_hdcp_request_srm(struct drm_device 
> *drm_dev)
>   goto exit;
>  
>   if (fw->size && fw->data)
> - drm_hdcp_srm_update(fw->data, fw->size);
> + drm_hdcp_srm_update(fw->data, fw->size, srm_data);
>  
>  exit:
>   release_firmware(fw);
> @@ -284,35 +285,33 @@ static void drm_hdcp_request_srm(struct drm_device 
> *drm_dev)
>  bool drm_hdcp_check_ksvs_revoked(struct drm_device *drm_dev, u8 *ksvs,

Unrelated nit: This function should really return int and let the caller decide 
what to do
with the result.

>u32 ksv_count)
>  {
> - u32 rev_ksv_cnt, cnt, i, j;
> + struct hdcp_srm *srm_data;
>   u8 *rev_ksv_list;
> + bool ret = false;
> + u32 cnt, i, j;
>  
> + srm_data = kzalloc(sizeof(*srm_data), GFP_KERNEL);

No need to put srm_data on the heap, it's only a pointer and a u32.

>   if (!srm_data)
> - return false;
> + return ret;
>  
> - mutex_lock(_data->mutex);
> - drm_hdcp_request_srm(drm_dev);
> -
> - rev_ksv_cnt = srm_data->revoked_ksv_cnt;
> + drm_hdcp_request_srm(drm_dev, srm_data);
>   rev_ksv_list = srm_data->revoked_ksv_list;
>  
>   /* If the Revoked ksv list is empty */
> - if (!rev_ksv_cnt || !rev_ksv_list) {
> - mutex_unlock(_data->mutex);
> - return false;
> - }
> + if (!srm_data->revoked_ksv_cnt || !rev_ksv_list)

You can't have one of these true without the other, right?

I think you should just reverse the loops below and remove this condition
entirely.

> + goto out;
>  
>   for  (cnt = 0; cnt < ksv_count; cnt++) {
>   rev_ksv_list = srm_data->revoked_ksv_list;
> - for (i = 0; i < rev_ksv_cnt; i++) {
> + for (i = 0; i < 

[RFC] drm/hdcp: optimizing the srm handling

2020-01-20 Thread Ramalingam C
As we are not using the sysfs infrastructure anymore, link to it is
removed. And global srm data and mutex to protect it are removed,
with required handling at revocation check function.

Yet to test hence RFC tag is added.

Signed-off-by: Ramalingam C 
Suggested-by: Sean Paul 
---
 drivers/gpu/drm/drm_hdcp.c | 68 ++
 drivers/gpu/drm/drm_internal.h |  4 --
 drivers/gpu/drm/drm_sysfs.c|  2 -
 3 files changed, 27 insertions(+), 47 deletions(-)

diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c
index 9191633a3c43..cc08d953eb53 100644
--- a/drivers/gpu/drm/drm_hdcp.c
+++ b/drivers/gpu/drm/drm_hdcp.c
@@ -23,13 +23,10 @@
 
 #include "drm_internal.h"
 
-static struct hdcp_srm {
+struct hdcp_srm {
u32 revoked_ksv_cnt;
u8 *revoked_ksv_list;
-
-   /* Mutex to protect above struct member */
-   struct mutex mutex;
-} *srm_data;
+};
 
 static inline void drm_hdcp_print_ksv(const u8 *ksv)
 {
@@ -91,7 +88,8 @@ static inline u32 get_vrl_length(const u8 *buf)
return drm_hdcp_be24_to_cpu(buf);
 }
 
-static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count)
+static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count,
+   struct hdcp_srm *srm_data)
 {
struct hdcp_srm_header *header;
u32 vrl_length, ksv_count;
@@ -153,7 +151,8 @@ static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t 
count)
return count;
 }
 
-static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count)
+static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count,
+   struct hdcp_srm *srm_data)
 {
struct hdcp_srm_header *header;
u32 vrl_length, ksv_count, ksv_sz;
@@ -226,18 +225,20 @@ static inline bool is_srm_version_hdcp2(const u8 *buf)
return *buf == (u8)(DRM_HDCP_2_SRM_ID << 4 | DRM_HDCP_2_INDICATOR);
 }
 
-static void drm_hdcp_srm_update(const u8 *buf, size_t count)
+static void drm_hdcp_srm_update(const u8 *buf, size_t count,
+   struct hdcp_srm *srm_data)
 {
if (count < sizeof(struct hdcp_srm_header))
return;
 
if (is_srm_version_hdcp1(buf))
-   drm_hdcp_parse_hdcp1_srm(buf, count);
+   drm_hdcp_parse_hdcp1_srm(buf, count, srm_data);
else if (is_srm_version_hdcp2(buf))
-   drm_hdcp_parse_hdcp2_srm(buf, count);
+   drm_hdcp_parse_hdcp2_srm(buf, count, srm_data);
 }
 
-static void drm_hdcp_request_srm(struct drm_device *drm_dev)
+static void drm_hdcp_request_srm(struct drm_device *drm_dev,
+struct hdcp_srm *srm_data)
 {
char fw_name[36] = "display_hdcp_srm.bin";
const struct firmware *fw;
@@ -250,7 +251,7 @@ static void drm_hdcp_request_srm(struct drm_device *drm_dev)
goto exit;
 
if (fw->size && fw->data)
-   drm_hdcp_srm_update(fw->data, fw->size);
+   drm_hdcp_srm_update(fw->data, fw->size, srm_data);
 
 exit:
release_firmware(fw);
@@ -284,35 +285,33 @@ static void drm_hdcp_request_srm(struct drm_device 
*drm_dev)
 bool drm_hdcp_check_ksvs_revoked(struct drm_device *drm_dev, u8 *ksvs,
 u32 ksv_count)
 {
-   u32 rev_ksv_cnt, cnt, i, j;
+   struct hdcp_srm *srm_data;
u8 *rev_ksv_list;
+   bool ret = false;
+   u32 cnt, i, j;
 
+   srm_data = kzalloc(sizeof(*srm_data), GFP_KERNEL);
if (!srm_data)
-   return false;
+   return ret;
 
-   mutex_lock(_data->mutex);
-   drm_hdcp_request_srm(drm_dev);
-
-   rev_ksv_cnt = srm_data->revoked_ksv_cnt;
+   drm_hdcp_request_srm(drm_dev, srm_data);
rev_ksv_list = srm_data->revoked_ksv_list;
 
/* If the Revoked ksv list is empty */
-   if (!rev_ksv_cnt || !rev_ksv_list) {
-   mutex_unlock(_data->mutex);
-   return false;
-   }
+   if (!srm_data->revoked_ksv_cnt || !rev_ksv_list)
+   goto out;
 
for  (cnt = 0; cnt < ksv_count; cnt++) {
rev_ksv_list = srm_data->revoked_ksv_list;
-   for (i = 0; i < rev_ksv_cnt; i++) {
+   for (i = 0; i < srm_data->revoked_ksv_cnt; i++) {
for (j = 0; j < DRM_HDCP_KSV_LEN; j++)
if (ksvs[j] != rev_ksv_list[j]) {
break;
} else if (j == (DRM_HDCP_KSV_LEN - 1)) {
DRM_DEBUG("Revoked KSV is ");
drm_hdcp_print_ksv(ksvs);
-   mutex_unlock(_data->mutex);
-   return true;
+   ret = true;
+   goto out;
}
/* Move the offset to next KSV in the