[PATCH] drm/amd/amdkfd: Fix large framesize for kfd_smi_ev_read()

[PATCH] drm/amd/amdkfd: Fix large framesize for kfd_smi_ev_read()

[Aurabindo Pillai]

The buffer allocated is of 1024 bytes. Allocate this from
heap instead of stack.

Also remove check for stack size since we're allocating from heap

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Amber Lin <Amber.Lin@amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 26 +++++++++++++++------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
index f5fd18eacf0d..5aebe169f8c6 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
@@ -77,9 +77,11 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
 	int ret;
 	size_t to_copy;
 	struct kfd_smi_client *client = filep->private_data;
-	unsigned char buf[MAX_KFIFO_SIZE];
+	unsigned char *buf;
 
-	BUILD_BUG_ON(MAX_KFIFO_SIZE > 1024);
+	buf = kzalloc(MAX_KFIFO_SIZE * sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
 	/* kfifo_to_user can sleep so we can't use spinlock protection around
 	 * it. Instead, we kfifo out as spinlocked then copy them to the user.
@@ -88,19 +90,29 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
 	to_copy = kfifo_len(&client->fifo);
 	if (!to_copy) {
 		spin_unlock(&client->lock);
-		return -EAGAIN;
+		ret = -EAGAIN;
+		goto ret_err;
 	}
 	to_copy = min3(size, sizeof(buf), to_copy);
 	ret = kfifo_out(&client->fifo, buf, to_copy);
 	spin_unlock(&client->lock);
-	if (ret <= 0)
-		return -EAGAIN;
+	if (ret <= 0) {
+		ret = -EAGAIN;
+		goto ret_err;
+	}
 
 	ret = copy_to_user(user, buf, to_copy);
-	if (ret)
-		return -EFAULT;
+	if (ret) {
+		ret = -EFAULT;
+		goto ret_err;
+	}
 
+	kfree(buf);
 	return to_copy;
+
+ret_err:
+	kfree(buf);
+	return ret;
 }
 
 static ssize_t kfd_smi_ev_write(struct file *filep, const char __user *user,
-- 
2.25.1

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Re: [PATCH] drm/amd/amdkfd: Fix large framesize for kfd_smi_ev_read()

[Alex Deucher]

On Wed, May 20, 2020 at 9:53 AM Aurabindo Pillai
<aurabindo.pillai@amd.com> wrote:
>
> The buffer allocated is of 1024 bytes. Allocate this from
> heap instead of stack.
>
> Also remove check for stack size since we're allocating from heap
>
> Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
> Tested-by: Amber Lin <Amber.Lin@amd.com>

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 26 +++++++++++++++------
>  1 file changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> index f5fd18eacf0d..5aebe169f8c6 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> @@ -77,9 +77,11 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
>         int ret;
>         size_t to_copy;
>         struct kfd_smi_client *client = filep->private_data;
> -       unsigned char buf[MAX_KFIFO_SIZE];
> +       unsigned char *buf;
>
> -       BUILD_BUG_ON(MAX_KFIFO_SIZE > 1024);
> +       buf = kzalloc(MAX_KFIFO_SIZE * sizeof(*buf), GFP_KERNEL);
> +       if (!buf)
> +               return -ENOMEM;
>
>         /* kfifo_to_user can sleep so we can't use spinlock protection around
>          * it. Instead, we kfifo out as spinlocked then copy them to the user.
> @@ -88,19 +90,29 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
>         to_copy = kfifo_len(&client->fifo);
>         if (!to_copy) {
>                 spin_unlock(&client->lock);
> -               return -EAGAIN;
> +               ret = -EAGAIN;
> +               goto ret_err;
>         }
>         to_copy = min3(size, sizeof(buf), to_copy);
>         ret = kfifo_out(&client->fifo, buf, to_copy);
>         spin_unlock(&client->lock);
> -       if (ret <= 0)
> -               return -EAGAIN;
> +       if (ret <= 0) {
> +               ret = -EAGAIN;
> +               goto ret_err;
> +       }
>
>         ret = copy_to_user(user, buf, to_copy);
> -       if (ret)
> -               return -EFAULT;
> +       if (ret) {
> +               ret = -EFAULT;
> +               goto ret_err;
> +       }
>
> +       kfree(buf);
>         return to_copy;
> +
> +ret_err:
> +       kfree(buf);
> +       return ret;
>  }
>
>  static ssize_t kfd_smi_ev_write(struct file *filep, const char __user *user,
> --
> 2.25.1
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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Re: [PATCH] drm/amd/amdkfd: Fix large framesize for kfd_smi_ev_read()

[Felix Kuehling]

Am 2020-05-20 um 9:53 a.m. schrieb Aurabindo Pillai:
> The buffer allocated is of 1024 bytes. Allocate this from
> heap instead of stack.
>
> Also remove check for stack size since we're allocating from heap
>
> Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
> Tested-by: Amber Lin <Amber.Lin@amd.com>

See one comment inline. With that fixed, the patch is

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>


> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 26 +++++++++++++++------
>  1 file changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> index f5fd18eacf0d..5aebe169f8c6 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> @@ -77,9 +77,11 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
>  	int ret;
>  	size_t to_copy;
>  	struct kfd_smi_client *client = filep->private_data;
> -	unsigned char buf[MAX_KFIFO_SIZE];
> +	unsigned char *buf;
>  
> -	BUILD_BUG_ON(MAX_KFIFO_SIZE > 1024);
> +	buf = kzalloc(MAX_KFIFO_SIZE * sizeof(*buf), GFP_KERNEL);

kzalloc is not necessary here, you could use kmalloc. The part of that
allocation that matters will be overwritten by kfifo_out.

Regards,
  Felix


> +	if (!buf)
> +		return -ENOMEM;
>  
>  	/* kfifo_to_user can sleep so we can't use spinlock protection around
>  	 * it. Instead, we kfifo out as spinlocked then copy them to the user.
> @@ -88,19 +90,29 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
>  	to_copy = kfifo_len(&client->fifo);
>  	if (!to_copy) {
>  		spin_unlock(&client->lock);
> -		return -EAGAIN;
> +		ret = -EAGAIN;
> +		goto ret_err;
>  	}
>  	to_copy = min3(size, sizeof(buf), to_copy);
>  	ret = kfifo_out(&client->fifo, buf, to_copy);
>  	spin_unlock(&client->lock);
> -	if (ret <= 0)
> -		return -EAGAIN;
> +	if (ret <= 0) {
> +		ret = -EAGAIN;
> +		goto ret_err;
> +	}
>  
>  	ret = copy_to_user(user, buf, to_copy);
> -	if (ret)
> -		return -EFAULT;
> +	if (ret) {
> +		ret = -EFAULT;
> +		goto ret_err;
> +	}
>  
> +	kfree(buf);
>  	return to_copy;
> +
> +ret_err:
> +	kfree(buf);
> +	return ret;
>  }
>  
>  static ssize_t kfd_smi_ev_write(struct file *filep, const char __user *user,
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Re: [PATCH] drm/amd/amdkfd: Fix large framesize for kfd_smi_ev_read()

[Aurabindo Pillai]

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On 05/20, Felix Kuehling wrote:
> Am 2020-05-20 um 9:53 a.m. schrieb Aurabindo Pillai:
> > The buffer allocated is of 1024 bytes. Allocate this from
> > heap instead of stack.
> >
> > Also remove check for stack size since we're allocating from heap
> >
> > Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
> > Tested-by: Amber Lin <Amber.Lin@amd.com>
> 
> See one comment inline. With that fixed, the patch is
> 
> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
> 
> 
> > ---
> >  drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 26 +++++++++++++++------
> >  1 file changed, 19 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> > index f5fd18eacf0d..5aebe169f8c6 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> > @@ -77,9 +77,11 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
> >  	int ret;
> >  	size_t to_copy;
> >  	struct kfd_smi_client *client = filep->private_data;
> > -	unsigned char buf[MAX_KFIFO_SIZE];
> > +	unsigned char *buf;
> >  
> > -	BUILD_BUG_ON(MAX_KFIFO_SIZE > 1024);
> > +	buf = kzalloc(MAX_KFIFO_SIZE * sizeof(*buf), GFP_KERNEL);
> 
> kzalloc is not necessary here, you could use kmalloc. The part of that
> allocation that matters will be overwritten by kfifo_out.
> 
> Regards,
>   Felix
> 
>

Thank you Felix, Alex for the review. I shall make that change and submit it.


Thanks & Regards,
Aurabindo

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