2021-04-20 05:55:18

by Avri Altman

Subject: [PATCH v3 1/2] mmc: block: Issue flush only if allowed

The cache may be flushed to the nonvolatile storage by writing to
FLUSH_CACHE byte (EXT_CSD byte [32]). When in command queueing mode, the
cache may be flushed by issuing a CMDQ_TASK_ DEV_MGMT (CMD48) with a
FLUSH_CACHE op-code. Either way, verify that The cache function is
turned ON before doing so.

fixes: 1e8e55b67030 (mmc: block: Add CQE support)

Reported-by: Brendan Peter <[email protected]>
Tested-by: Brendan Peter <[email protected]>
Signed-off-by: Avri Altman <[email protected]>
---
drivers/mmc/core/block.c | 7 +++++++
drivers/mmc/core/mmc.c | 2 +-
drivers/mmc/core/mmc_ops.h | 5 +++++
3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 8bfd4d95b386..5b6501fc9fb7 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1476,6 +1476,11 @@ static int mmc_blk_cqe_issue_flush(struct mmc_queue *mq, struct request *req)
struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
struct mmc_request *mrq = mmc_blk_cqe_prep_dcmd(mqrq, req);

+ if (mmc_card_mmc(mq->card) && !mmc_flush_allowed(mq->card)) {
+ blk_mq_end_request(req, BLK_STS_OK);
+ return -EPERM;
+ }
+
mrq->cmd->opcode = MMC_SWITCH;
mrq->cmd->arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
(EXT_CSD_FLUSH_CACHE << 16) |
@@ -2226,6 +2231,8 @@ enum mmc_issued mmc_blk_mq_issue_rq(struct mmc_queue *mq, struct request *req)
switch (req_op(req)) {
case REQ_OP_FLUSH:
ret = mmc_blk_cqe_issue_flush(mq, req);
+ if (ret == -EPERM)
+ return MMC_REQ_FINISHED;
break;
case REQ_OP_READ:
case REQ_OP_WRITE:
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 9ad4aa537867..e3da62ffcb5e 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -2037,7 +2037,7 @@ static int _mmc_flush_cache(struct mmc_card *card)
{
int err = 0;

- if (card->ext_csd.cache_size > 0 && card->ext_csd.cache_ctrl & 1) {
+ if (mmc_flush_allowed(card)) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_FLUSH_CACHE, 1,
CACHE_FLUSH_TIMEOUT_MS);
diff --git a/drivers/mmc/core/mmc_ops.h b/drivers/mmc/core/mmc_ops.h
index 5782fdf4e8e9..2682bf66708a 100644
--- a/drivers/mmc/core/mmc_ops.h
+++ b/drivers/mmc/core/mmc_ops.h
@@ -19,6 +19,11 @@ enum mmc_busy_cmd {
struct mmc_host;
struct mmc_card;

+static inline bool mmc_flush_allowed(struct mmc_card *card)
+{
+ return card->ext_csd.cache_size > 0 && card->ext_csd.cache_ctrl & 1;
+}
+
int mmc_select_card(struct mmc_card *card);
int mmc_deselect_cards(struct mmc_host *host);
int mmc_set_dsr(struct mmc_host *host);
--
2.25.1

2021-04-20 11:21:47

by Adrian Hunter

Subject: Re: [PATCH v3 1/2] mmc: block: Issue flush only if allowed

On 20/04/21 8:53 am, Avri Altman wrote:
> The cache may be flushed to the nonvolatile storage by writing to
> FLUSH_CACHE byte (EXT_CSD byte [32]). When in command queueing mode, the
> cache may be flushed by issuing a CMDQ_TASK_ DEV_MGMT (CMD48) with a
> FLUSH_CACHE op-code. Either way, verify that The cache function is
> turned ON before doing so.
>
> fixes: 1e8e55b67030 (mmc: block: Add CQE support)
>
> Reported-by: Brendan Peter <[email protected]>
> Tested-by: Brendan Peter <[email protected]>
> Signed-off-by: Avri Altman <[email protected]>
> ---
> drivers/mmc/core/block.c | 7 +++++++
> drivers/mmc/core/mmc.c | 2 +-
> drivers/mmc/core/mmc_ops.h | 5 +++++
> 3 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 8bfd4d95b386..5b6501fc9fb7 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -1476,6 +1476,11 @@ static int mmc_blk_cqe_issue_flush(struct mmc_queue *mq, struct request *req)
> struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
> struct mmc_request *mrq = mmc_blk_cqe_prep_dcmd(mqrq, req);
>
> + if (mmc_card_mmc(mq->card) && !mmc_flush_allowed(mq->card)) {
> + blk_mq_end_request(req, BLK_STS_OK);
> + return -EPERM;
> + }
> +
> mrq->cmd->opcode = MMC_SWITCH;
> mrq->cmd->arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
> (EXT_CSD_FLUSH_CACHE << 16) |
> @@ -2226,6 +2231,8 @@ enum mmc_issued mmc_blk_mq_issue_rq(struct mmc_queue *mq, struct request *req)
> switch (req_op(req)) {
> case REQ_OP_FLUSH:
> ret = mmc_blk_cqe_issue_flush(mq, req);
> + if (ret == -EPERM)
> + return MMC_REQ_FINISHED;

Using an error code for this case seems a little fragile.

How about something like:

case REQ_OP_FLUSH:
if (mmc_blk_cache_disabled(mq->card)) {
blk_mq_end_request(req, BLK_STS_OK);
return MMC_REQ_FINISHED;
}
ret = mmc_blk_cqe_issue_flush(mq, req);


static bool mmc_blk_cache_disabled(struct mmc_card *card)
{
return mmc_card_mmc(mq->card) && !mmc_flush_allowed(card);
}

> break;
> case REQ_OP_READ:
> case REQ_OP_WRITE:
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 9ad4aa537867..e3da62ffcb5e 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -2037,7 +2037,7 @@ static int _mmc_flush_cache(struct mmc_card *card)
> {
> int err = 0;
>
> - if (card->ext_csd.cache_size > 0 && card->ext_csd.cache_ctrl & 1) {
> + if (mmc_flush_allowed(card)) {
> err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> EXT_CSD_FLUSH_CACHE, 1,
> CACHE_FLUSH_TIMEOUT_MS);
> diff --git a/drivers/mmc/core/mmc_ops.h b/drivers/mmc/core/mmc_ops.h
> index 5782fdf4e8e9..2682bf66708a 100644
> --- a/drivers/mmc/core/mmc_ops.h
> +++ b/drivers/mmc/core/mmc_ops.h
> @@ -19,6 +19,11 @@ enum mmc_busy_cmd {
> struct mmc_host;
> struct mmc_card;
>
> +static inline bool mmc_flush_allowed(struct mmc_card *card)
> +{
> + return card->ext_csd.cache_size > 0 && card->ext_csd.cache_ctrl & 1;
> +}
> +
> int mmc_select_card(struct mmc_card *card);
> int mmc_deselect_cards(struct mmc_host *host);
> int mmc_set_dsr(struct mmc_host *host);
>

2021-04-20 13:23:55

by Avri Altman

Subject: RE: [PATCH v3 1/2] mmc: block: Issue flush only if allowed

> On 20/04/21 8:53 am, Avri Altman wrote:
> > The cache may be flushed to the nonvolatile storage by writing to
> > FLUSH_CACHE byte (EXT_CSD byte [32]). When in command queueing mode,
> the
> > cache may be flushed by issuing a CMDQ_TASK_ DEV_MGMT (CMD48) with a
> > FLUSH_CACHE op-code. Either way, verify that The cache function is
> > turned ON before doing so.
> >
> > fixes: 1e8e55b67030 (mmc: block: Add CQE support)
> >
> > Reported-by: Brendan Peter <[email protected]>
> > Tested-by: Brendan Peter <[email protected]>
> > Signed-off-by: Avri Altman <[email protected]>
> > ---
> > drivers/mmc/core/block.c | 7 +++++++
> > drivers/mmc/core/mmc.c | 2 +-
> > drivers/mmc/core/mmc_ops.h | 5 +++++
> > 3 files changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> > index 8bfd4d95b386..5b6501fc9fb7 100644
> > --- a/drivers/mmc/core/block.c
> > +++ b/drivers/mmc/core/block.c
> > @@ -1476,6 +1476,11 @@ static int mmc_blk_cqe_issue_flush(struct
> mmc_queue *mq, struct request *req)
> > struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
> > struct mmc_request *mrq = mmc_blk_cqe_prep_dcmd(mqrq, req);
> >
> > + if (mmc_card_mmc(mq->card) && !mmc_flush_allowed(mq->card)) {
> > + blk_mq_end_request(req, BLK_STS_OK);
> > + return -EPERM;
> > + }
> > +
> > mrq->cmd->opcode = MMC_SWITCH;
> > mrq->cmd->arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
> > (EXT_CSD_FLUSH_CACHE << 16) |
> > @@ -2226,6 +2231,8 @@ enum mmc_issued mmc_blk_mq_issue_rq(struct
> mmc_queue *mq, struct request *req)
> > switch (req_op(req)) {
> > case REQ_OP_FLUSH:
> > ret = mmc_blk_cqe_issue_flush(mq, req);
> > + if (ret == -EPERM)
> > + return MMC_REQ_FINISHED;
>
> Using an error code for this case seems a little fragile.
>
> How about something like:
>
> case REQ_OP_FLUSH:
> if (mmc_blk_cache_disabled(mq->card)) {
> blk_mq_end_request(req, BLK_STS_OK);
> return MMC_REQ_FINISHED;
> }
> ret = mmc_blk_cqe_issue_flush(mq, req);
>
>
> static bool mmc_blk_cache_disabled(struct mmc_card *card)
> {
> return mmc_card_mmc(mq->card) && !mmc_flush_allowed(card);
> }
Done.

Thanks,
Avri