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authorPer Forlin <per.forlin@linaro.org>2011-08-29 15:35:58 +0200
committerChris Ball <cjb@laptop.org>2011-10-26 16:32:04 -0400
commit7c8a2829c22a270acadc6aa3a937e2e7956b19f5 (patch)
treeb787b429a1bd01f364e752fe5b52e2f95cb46875
parent44669034815a7ad263542ac605c581a10b22d146 (diff)
downloadlinux-7c8a2829c22a270acadc6aa3a937e2e7956b19f5.tar.bz2
mmc: core: clarify how to use post_req in case of errors
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 an error. Signed-off-by: Per Forlin <per.forlin@linaro.org> Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Chris Ball <cjb@laptop.org>
-rw-r--r--drivers/mmc/core/core.c6
-rw-r--r--include/linux/mmc/host.h3
2 files changed, 9 insertions, 0 deletions
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 45ea968e7dd1..0b4c2ed22bce 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -320,8 +320,14 @@ 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 4c4bddf5ef61..340cc0c9409f 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -109,6 +109,9 @@ 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);