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

From: Adrian Hunter
Date: Wed Aug 16 2017 - 06:20:46 EST


On 15/08/17 18:11, Arnd Bergmann 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@xxxxxxxx>

Apart from duplicate blank line pointed out below:

Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Tested-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>

> ---
> 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;
> }
> +
> +

Duplicate blank line

> 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)
> {
>