The err condition in post_req() is set to undo a call made to pre_req() that hasn't been started yet. The err condition is not set if an MMC request returns error.
Signed-off-by: Per Forlin per.forlin@linaro.org --- drivers/mmc/core/core.c | 6 ++++++ include/linux/mmc/host.h | 3 +++ 2 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 91a0a74..542aa06 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -279,8 +279,14 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host, mmc_wait_for_req_done(host, host->areq->mrq); err = host->areq->err_check(host->card, host->areq); if (err) { + /* post process the completed failed request */ mmc_post_req(host, host->areq->mrq, 0); if (areq) + /* + * Cancel the new prepared request, because + * it can't run until the failed + * request has been properly handled. + */ mmc_post_req(host, areq->mrq, -EINVAL);
host->areq = NULL; diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 1d09562..7896fb4 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -108,6 +108,9 @@ struct mmc_host_ops { * It is optional for the host to implement pre_req and post_req in * order to support double buffering of requests (prepare one * request while another request is active). + * pre_req() must always be followed by a post_req(). + * To undo a call made to pre_req(), call post_req() with + * a nonzero err condition. */ void (*post_req)(struct mmc_host *host, struct mmc_request *req, int err);