On Mon, Jul 30, 2012 at 7:34 AM, Kyungsik Lee <kyungsik.lee@xxxxxxx> wrote:
> It is expected that Extended CSD register(the size of this register
> is larger than CID/CSD) will be referenced more frequently as more
> fields have been added to Extended CSD and it seems that it is not
> a good option to double the memory used.
>
> This patch is intended to avoid the use of bounce buffer for reading
> Extended CSD register in mmc_send_cxd_data().
Maybe I am reading this wrong, but mmc_send_cid and mmc_send_csd are always
called with card->raw_cid and card->raw_csd, which are allocated from the heap,
(from mmc_alloc_card).
So the second half of your changes are not required, or a WARN_ON
might suffice ?
>
> Signed-off-by: Kyungsik Lee <kyungsik.lee@xxxxxxx>
> ---
> Changes in v2:
> - Handling on-stack buffer if it's used in caller.
> ---
> drivers/mmc/core/mmc_ops.c | 56 ++++++++++++++++++++++++++++++++++---------
> 1 files changed, 44 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> index 0ed2cc5..dae5492 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -239,13 +239,19 @@ mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
> struct mmc_data data = {0};
> struct scatterlist sg;
> void *data_buf;
> + int is_on_stack;
>
> - /* dma onto stack is unsafe/nonportable, but callers to this
> - * routine normally provide temporary on-stack buffers ...
> - */
> - data_buf = kmalloc(len, GFP_KERNEL);
> - if (data_buf == NULL)
> - return -ENOMEM;
> + is_on_stack = object_is_on_stack(buf);
> + if (is_on_stack) {
> +
> + /* dma onto stack is unsafe/nonportable, but callers to this
> + * routine normally provide temporary on-stack buffers ...
> + */
> + data_buf = kmalloc(len, GFP_KERNEL);
> + if (data_buf == NULL)
> + return -ENOMEM;
> + } else
> + data_buf = buf;
>
> mrq.cmd = &cmd;
> mrq.data = &data;
> @@ -280,8 +286,10 @@ mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
>
> mmc_wait_for_req(host, &mrq);
>
> - memcpy(buf, data_buf, len);
> - kfree(data_buf);
> + if (is_on_stack) {
> + memcpy(buf, data_buf, len);
> + kfree(data_buf);
> + }
>
> if (cmd.error)
> return cmd.error;
> @@ -294,24 +302,37 @@ mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
> int mmc_send_csd(struct mmc_card *card, u32 *csd)
> {
> int ret, i;
> + u32 *csd_tmp;
>
> if (!mmc_host_is_spi(card->host))
> return mmc_send_cxd_native(card->host, card->rca << 16,
> csd, MMC_SEND_CSD);
>
> - ret = mmc_send_cxd_data(card, card->host, MMC_SEND_CSD, csd, 16);
> + csd_tmp = kmalloc(16, GFP_KERNEL);
> + if (!csd_tmp)
> + return -ENOMEM;
> +
> + ret = mmc_send_cxd_data(card, card->host, MMC_SEND_CSD, csd_tmp, 16);
> if (ret)
> - return ret;
> + goto err;
> +
> + memcpy(csd, csd_tmp, 16);
>
> for (i = 0;i < 4;i++)
> csd[i] = be32_to_cpu(csd[i]);
>
> + kfree(csd_tmp);
> return 0;
> +
> +err:
> + kfree(csd_tmp);
> + return ret;
> }
>
> int mmc_send_cid(struct mmc_host *host, u32 *cid)
> {
> int ret, i;
> + u32 *cid_tmp;
>
> if (!mmc_host_is_spi(host)) {
> if (!host->card)
> @@ -320,14 +341,25 @@ int mmc_send_cid(struct mmc_host *host, u32 *cid)
> cid, MMC_SEND_CID);
> }
>
> - ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid, 16);
> + cid_tmp = kmalloc(16, GFP_KERNEL);
> + if (!cid_tmp)
> + return -ENOMEM;
> +
> + ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16);
> if (ret)
> - return ret;
> + goto err;
> +
> + memcpy(cid, cid_tmp, 16);
>
> for (i = 0;i < 4;i++)
> cid[i] = be32_to_cpu(cid[i]);
>
> + kfree(cid_tmp);
> return 0;
> +
> +err:
> + kfree(cid_tmp);
> + return ret;
> }
>
> int mmc_send_ext_csd(struct mmc_card *card, u8 *ext_csd)
> --
> 1.7.0.4
>
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