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 <bernard@xxxxxxxx>
> ---
> 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(&ipu->channel_lock);
>
> - list_for_each_entry(channel, &ipu->channels, list) {
> - if (channel->num == num) {
> + list_for_each_entry(entry, &ipu->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(&channel->list, &ipu->channels);
>
> out:
> @@ -308,9 +309,10 @@ void ipu_idmac_put(struct ipuv3_channel *channel)
> mutex_lock(&ipu->channel_lock);
>
> list_del(&channel->list);
> - kfree(channel);
>
> mutex_unlock(&ipu->channel_lock);
> +
> + kfree(channel);
> }
> EXPORT_SYMBOL_GPL(ipu_idmac_put);
regards
Philipp
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