[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 at 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 at amd.com>
> Tested-by: Amber Lin <Amber.Lin at amd.com>

Reviewed-by: Alex Deucher <alexander.deucher at 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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