Re: [Re-send][PATCH] gpu/ipu-v3:reduce protected code area in ipu idmac get/put

[Philipp Zabel]

Hi Bernard,

On Mon, 2020-09-21 at 19:11 +0800, Bernard wrote:
> This change will speed-up a bit these ipu_idmac_get &
> ipu_idmac_put processing and there is no need to protect
> kzalloc & kfree.

I don't think that will be measurable, the channel lock is very unlikely
to be contended. It might make more sense to replace the list walk with
a bitfield.

> Signed-off-by: Bernard Zhao 
> ---
>  drivers/gpu/ipu-v3/ipu-common.c | 24 +---
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/ipu-v3/ipu-common.c b/drivers/gpu/ipu-v3/ipu-common.c
> index b3dae9ec1a38..8b3a57864c2e 100644
> --- a/drivers/gpu/ipu-v3/ipu-common.c
> +++ b/drivers/gpu/ipu-v3/ipu-common.c
> @@ -267,29 +267,30 @@ EXPORT_SYMBOL_GPL(ipu_rot_mode_to_degrees);
>  struct ipuv3_channel *ipu_idmac_get(struct ipu_soc *ipu, unsigned num)
>  {
>   struct ipuv3_channel *channel;
> + struct ipuv3_channel *entry;
>  
>   dev_dbg(ipu->dev, "%s %d\n", __func__, num);
>  
>   if (num > 63)
>   return ERR_PTR(-ENODEV);
>  
> + channel = kzalloc(sizeof(*channel), GFP_KERNEL);
> + if (!channel)
> + return ERR_PTR(-ENOMEM);
> +
> + channel->num = num;
> + channel->ipu = ipu;
> +
>   mutex_lock(>channel_lock);
>  
> - list_for_each_entry(channel, >channels, list) {
> - if (channel->num == num) {
> + list_for_each_entry(entry, >channels, list) {
> + if (entry->num == num) {
> + kfree(channel);
>   channel = ERR_PTR(-EBUSY);
>   goto out;

This leaks the channel memory allocated above.

>   }
>   }
> 
> - channel = kzalloc(sizeof(*channel), GFP_KERNEL);
> - if (!channel) {
> - channel = ERR_PTR(-ENOMEM);
> - goto out;
> - }
> -
> - channel->num = num;
> - channel->ipu = ipu;
>   list_add(>list, >channels);
>  
>  out:
> @@ -308,9 +309,10 @@ void ipu_idmac_put(struct ipuv3_channel *channel)
>   mutex_lock(>channel_lock);
>  
>   list_del(>list);
> - kfree(channel);
>  
>   mutex_unlock(>channel_lock);
> +
> + kfree(channel);
>  }
>  EXPORT_SYMBOL_GPL(ipu_idmac_put);

regards
Philipp

[Re-send][PATCH] gpu/ipu-v3:reduce protected code area in ipu idmac get/put

[Bernard]

This change will speed-up a bit these ipu_idmac_get &
ipu_idmac_put processing and there is no need to protect
kzalloc & kfree.

Signed-off-by: Bernard Zhao 
---
 drivers/gpu/ipu-v3/ipu-common.c | 24 +---
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-common.c b/drivers/gpu/ipu-v3/ipu-common.c
index b3dae9ec1a38..8b3a57864c2e 100644
--- a/drivers/gpu/ipu-v3/ipu-common.c
+++ b/drivers/gpu/ipu-v3/ipu-common.c
@@ -267,29 +267,30 @@ EXPORT_SYMBOL_GPL(ipu_rot_mode_to_degrees);
 struct ipuv3_channel *ipu_idmac_get(struct ipu_soc *ipu, unsigned num)
 {
struct ipuv3_channel *channel;
+   struct ipuv3_channel *entry;
 
dev_dbg(ipu->dev, "%s %d\n", __func__, num);
 
if (num > 63)
return ERR_PTR(-ENODEV);
 
+   channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+   if (!channel)
+   return ERR_PTR(-ENOMEM);
+
+   channel->num = num;
+   channel->ipu = ipu;
+
mutex_lock(>channel_lock);
 
-   list_for_each_entry(channel, >channels, list) {
-   if (channel->num == num) {
+   list_for_each_entry(entry, >channels, list) {
+   if (entry->num == num) {
+   kfree(channel);
channel = ERR_PTR(-EBUSY);
goto out;
}
}
 
-   channel = kzalloc(sizeof(*channel), GFP_KERNEL);
-   if (!channel) {
-   channel = ERR_PTR(-ENOMEM);
-   goto out;
-   }
-
-   channel->num = num;
-   channel->ipu = ipu;
list_add(>list, >channels);
 
 out:
@@ -308,9 +309,10 @@ void ipu_idmac_put(struct ipuv3_channel *channel)
mutex_lock(>channel_lock);
 
list_del(>list);
-   kfree(channel);
 
mutex_unlock(>channel_lock);
+
+   kfree(channel);
 }
 EXPORT_SYMBOL_GPL(ipu_idmac_put);
 
-- 
2.28.0

[PATCH] gpu/ipu-v3:reduce protected code area in ipu idmac get/put

[Bernard Zhao]

This change will speed-up a bit these ipu_idmac_get &
ipu_idmac_put processing and there is no need to protect
kzalloc & kfree.

Signed-off-by: Bernard Zhao 
---
 drivers/gpu/ipu-v3/ipu-common.c | 24 +---
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-common.c b/drivers/gpu/ipu-v3/ipu-common.c
index b3dae9ec1a38..8b3a57864c2e 100644
--- a/drivers/gpu/ipu-v3/ipu-common.c
+++ b/drivers/gpu/ipu-v3/ipu-common.c
@@ -267,29 +267,30 @@ EXPORT_SYMBOL_GPL(ipu_rot_mode_to_degrees);
 struct ipuv3_channel *ipu_idmac_get(struct ipu_soc *ipu, unsigned num)
 {
struct ipuv3_channel *channel;
+   struct ipuv3_channel *entry;
 
dev_dbg(ipu->dev, "%s %d\n", __func__, num);
 
if (num > 63)
return ERR_PTR(-ENODEV);
 
+   channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+   if (!channel)
+   return ERR_PTR(-ENOMEM);
+
+   channel->num = num;
+   channel->ipu = ipu;
+
mutex_lock(>channel_lock);
 
-   list_for_each_entry(channel, >channels, list) {
-   if (channel->num == num) {
+   list_for_each_entry(entry, >channels, list) {
+   if (entry->num == num) {
+   kfree(channel);
channel = ERR_PTR(-EBUSY);
goto out;
}
}
 
-   channel = kzalloc(sizeof(*channel), GFP_KERNEL);
-   if (!channel) {
-   channel = ERR_PTR(-ENOMEM);
-   goto out;
-   }
-
-   channel->num = num;
-   channel->ipu = ipu;
list_add(>list, >channels);
 
 out:
@@ -308,9 +309,10 @@ void ipu_idmac_put(struct ipuv3_channel *channel)
mutex_lock(>channel_lock);
 
list_del(>list);
-   kfree(channel);
 
mutex_unlock(>channel_lock);
+
+   kfree(channel);
 }
 EXPORT_SYMBOL_GPL(ipu_idmac_put);
 
-- 
2.28.0