Re: [PATCH 1/2] mmc: test: reduce stack usage in mmc_test_nonblock_transfer

[Ulf Hansson <ulf.hansson@linaro.org>]

On 15 August 2017 at 17:11, Arnd Bergmann <arnd@arndb.de> wrote:
> The new lockdep annotations for completions cause a warning in the
> mmc test module, in a function that now has four 150 byte structures
> on the stack:
>
> drivers/mmc/core/mmc_test.c: In function 'mmc_test_nonblock_transfer.constprop':
> drivers/mmc/core/mmc_test.c:892:1: error: the frame size of 1360 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
>
> The mmc_test_ongoing_transfer function evidently had a similar problem,
> and worked around it by using dynamic allocation.
>
> This generalizes the approach used by mmc_test_ongoing_transfer() and
> applies it to mmc_test_nonblock_transfer() as well.
>
> Fixes: cd8084f91c02 ("locking/lockdep: Apply crossrelease to completions")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks, applied for next!

Kind regards
Uffe

> ---
> The patch causing this is currently part of linux-next, scheduled for
> 4.14, so it would be good to have this in the same release.
>
> Since the change is not entirely trivial, please test this before applying.
> ---
>  drivers/mmc/core/mmc_test.c | 97 +++++++++++++++++++--------------------------
>  1 file changed, 41 insertions(+), 56 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc_test.c b/drivers/mmc/core/mmc_test.c
> index 7a304a6e5bf1..478869805b96 100644
> --- a/drivers/mmc/core/mmc_test.c
> +++ b/drivers/mmc/core/mmc_test.c
> @@ -800,38 +800,44 @@ static int mmc_test_check_broken_result(struct mmc_test_card *test,
>         return ret;
>  }
>
> +struct mmc_test_req {
> +       struct mmc_request mrq;
> +       struct mmc_command sbc;
> +       struct mmc_command cmd;
> +       struct mmc_command stop;
> +       struct mmc_command status;
> +       struct mmc_data data;
> +};
> +
>  /*
>   * Tests nonblock transfer with certain parameters
>   */
> -static void mmc_test_nonblock_reset(struct mmc_request *mrq,
> -                                   struct mmc_command *cmd,
> -                                   struct mmc_command *stop,
> -                                   struct mmc_data *data)
> +static void mmc_test_req_reset(struct mmc_test_req *rq)
> +{
> +       memset(rq, 0, sizeof(struct mmc_test_req));
> +
> +       rq->mrq.cmd = &rq->cmd;
> +       rq->mrq.data = &rq->data;
> +       rq->mrq.stop = &rq->stop;
> +}
> +
> +static struct mmc_test_req *mmc_test_req_alloc(void)
>  {
> -       memset(mrq, 0, sizeof(struct mmc_request));
> -       memset(cmd, 0, sizeof(struct mmc_command));
> -       memset(data, 0, sizeof(struct mmc_data));
> -       memset(stop, 0, sizeof(struct mmc_command));
> +       struct mmc_test_req *rq = kmalloc(sizeof(*rq), GFP_KERNEL);
>
> -       mrq->cmd = cmd;
> -       mrq->data = data;
> -       mrq->stop = stop;
> +       if (rq)
> +               mmc_test_req_reset(rq);
> +
> +       return rq;
>  }
> +
> +
>  static int mmc_test_nonblock_transfer(struct mmc_test_card *test,
>                                       struct scatterlist *sg, unsigned sg_len,
>                                       unsigned dev_addr, unsigned blocks,
>                                       unsigned blksz, int write, int count)
>  {
> -       struct mmc_request mrq1;
> -       struct mmc_command cmd1;
> -       struct mmc_command stop1;
> -       struct mmc_data data1;
> -
> -       struct mmc_request mrq2;
> -       struct mmc_command cmd2;
> -       struct mmc_command stop2;
> -       struct mmc_data data2;
> -
> +       struct mmc_test_req *rq1, *rq2;
>         struct mmc_test_async_req test_areq[2];
>         struct mmc_async_req *done_areq;
>         struct mmc_async_req *cur_areq = &test_areq[0].areq;
> @@ -843,12 +849,16 @@ static int mmc_test_nonblock_transfer(struct mmc_test_card *test,
>         test_areq[0].test = test;
>         test_areq[1].test = test;
>
> -       mmc_test_nonblock_reset(&mrq1, &cmd1, &stop1, &data1);
> -       mmc_test_nonblock_reset(&mrq2, &cmd2, &stop2, &data2);
> +       rq1 = mmc_test_req_alloc();
> +       rq2 = mmc_test_req_alloc();
> +       if (!rq1 || !rq2) {
> +               ret = RESULT_FAIL;
> +               goto err;
> +       }
>
> -       cur_areq->mrq = &mrq1;
> +       cur_areq->mrq = &rq1->mrq;
>         cur_areq->err_check = mmc_test_check_result_async;
> -       other_areq->mrq = &mrq2;
> +       other_areq->mrq = &rq2->mrq;
>         other_areq->err_check = mmc_test_check_result_async;
>
>         for (i = 0; i < count; i++) {
> @@ -861,14 +871,10 @@ static int mmc_test_nonblock_transfer(struct mmc_test_card *test,
>                         goto err;
>                 }
>
> -               if (done_areq) {
> -                       if (done_areq->mrq == &mrq2)
> -                               mmc_test_nonblock_reset(&mrq2, &cmd2,
> -                                                       &stop2, &data2);
> -                       else
> -                               mmc_test_nonblock_reset(&mrq1, &cmd1,
> -                                                       &stop1, &data1);
> -               }
> +               if (done_areq)
> +                       mmc_test_req_reset(container_of(done_areq->mrq,
> +                                               struct mmc_test_req, mrq));
> +
>                 swap(cur_areq, other_areq);
>                 dev_addr += blocks;
>         }
> @@ -877,8 +883,9 @@ static int mmc_test_nonblock_transfer(struct mmc_test_card *test,
>         if (status != MMC_BLK_SUCCESS)
>                 ret = RESULT_FAIL;
>
> -       return ret;
>  err:
> +       kfree(rq1);
> +       kfree(rq2);
>         return ret;
>  }
>
> @@ -2329,28 +2336,6 @@ static int mmc_test_reset(struct mmc_test_card *test)
>         return RESULT_FAIL;
>  }
>
> -struct mmc_test_req {
> -       struct mmc_request mrq;
> -       struct mmc_command sbc;
> -       struct mmc_command cmd;
> -       struct mmc_command stop;
> -       struct mmc_command status;
> -       struct mmc_data data;
> -};
> -
> -static struct mmc_test_req *mmc_test_req_alloc(void)
> -{
> -       struct mmc_test_req *rq = kzalloc(sizeof(*rq), GFP_KERNEL);
> -
> -       if (rq) {
> -               rq->mrq.cmd = &rq->cmd;
> -               rq->mrq.data = &rq->data;
> -               rq->mrq.stop = &rq->stop;
> -       }
> -
> -       return rq;
> -}
> -
>  static int mmc_test_send_status(struct mmc_test_card *test,
>                                 struct mmc_command *cmd)
>  {
> --
> 2.9.0
>