The while loop when handling rw request may become deadloop in
case of bad card
    I've seen mmcqd gets blocked forever after a single error message:

mmcblk0: error -110 sending read/write command, response 0x900, card
status 0x80e00

    Also there was case of card reports status without error

mmcblk0: error -110 sending read/write command, response 0x900, card
status 0xe00

    After this error, the card can stay in prg state, and never comes back,
    and may not report any error further. So a break out condition
    should be set in mmc block layer:
* should not enter the waiting loop in case of error
* should break out from the waiting loop, if card response with error
* should break out from the waiting loop when timeout

    These will not help with the card, one more thing to do:
* re-init the card in case of too many errors

Signed-off-by: Ethan Du <ethan....@gmail.com>
---
 drivers/mmc/card/block.c |   35 +++++++++++++++++++++++++++--------
 drivers/mmc/core/mmc.c   |    9 +++++++--
 drivers/mmc/core/sd.c    |    8 ++++++--
 include/linux/mmc/card.h |    3 +++
 include/linux/mmc/mmc.h  |    1 +
 5 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index d545f79..1d304a2 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -316,12 +316,14 @@ out:
        return err ? 0 : 1;
 }

+#define BUSY_TIMEOUT_MS (16 * 1024)
 static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 {
        struct mmc_blk_data *md = mq->data;
        struct mmc_card *card = md->queue.card;
        struct mmc_blk_request brq;
        int ret = 1, disable_multi = 0;
+       unsigned long timeout = 0;

        mmc_claim_host(card->host);

@@ -453,7 +455,9 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
*mq, struct request *req)
                               brq.stop.resp[0], status);
                }

-               if (!mmc_host_is_spi(card->host) && rq_data_dir(req) != READ) {
+               if (!mmc_host_is_spi(card->host) && rq_data_dir(req) != READ &&
+                   !brq.cmd.error && !brq.data.error && !brq.stop.error) {
+                       timeout = jiffies + msecs_to_jiffies(BUSY_TIMEOUT_MS);
                        do {
                                int err;

@@ -466,13 +470,22 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
*mq, struct request *req)
                                               req->rq_disk->disk_name, err);
                                        goto cmd_err;
                                }
+                               if (cmd.resp[0] & R1_ERROR_MASK) {
+                                       printk(KERN_ERR "%s: card err %#x\n",
+                                               req->rq_disk->disk_name,
+                                               cmd.resp[0]);
+                                       goto cmd_err;
+                               }
                                /*
                                 * Some cards mishandle the status bits,
                                 * so make sure to check both the busy
                                 * indication and the card state.
                                 */
-                       } while (!(cmd.resp[0] & R1_READY_FOR_DATA) ||
-                               (R1_CURRENT_STATE(cmd.resp[0]) == 7));
+                               if ((cmd.resp[0] & R1_READY_FOR_DATA) &&
+                                   (R1_CURRENT_STATE(cmd.resp[0]) != 7))
+                                       break;
+                       } while (time_before(jiffies, timeout));
+                       /* Ignore timeout out */

 #if 0
                        if (cmd.resp[0] & ~0x00000900)
@@ -510,11 +523,11 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
*mq, struct request *req)

        return 1;

- cmd_err:
-       /*
-        * If this is an SD card and we're writing, we can first
-        * mark the known good sectors as ok.
-        *
+cmd_err:
+       /*
+        * If this is an SD card and we're writing, we can first
+        * mark the known good sectors as ok.
+        *
         * If the card is not SD, we can still ok written sectors
         * as reported by the controller (which might be less than
         * the real number of written sectors, but never more).
@@ -541,6 +554,12 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
*mq, struct request *req)
                ret = __blk_end_request(req, -EIO, blk_rq_cur_bytes(req));
        spin_unlock_irq(&md->lock);

+       card->err_count++;
+       if (card->err_count >= ERR_TRIGGER_REINIT) {
+               printk(KERN_WARNING "%s: re-init the card due to error\n",
+                       req->rq_disk->disk_name);
+               mmc_detect_change(card->host, 0);
+       }
        return 0;
 }

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 6909a54..79c4759 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -535,6 +535,8 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,

        if (!oldcard)
                host->card = card;
+       else
+               oldcard->err_count = 0;

        return 0;

@@ -563,17 +565,20 @@ static void mmc_remove(struct mmc_host *host)
  */
 static void mmc_detect(struct mmc_host *host)
 {
-       int err;
+       int err = 0;

        BUG_ON(!host);
        BUG_ON(!host->card);

        mmc_claim_host(host);

+       if (host->card->err_count >= ERR_TRIGGER_REINIT)
+               err = mmc_init_card(host, host->ocr, host->card);
        /*
         * Just check if our card has been removed.
         */
-       err = mmc_send_status(host->card, NULL);
+       if (!err)
+               err = mmc_send_status(host->card, NULL);

        mmc_release_host(host);

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 0f52410..820b0d1 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -635,6 +635,7 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
                mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
        }

+       card->err_count = 0;
        host->card = card;
        return 0;

@@ -662,17 +663,20 @@ static void mmc_sd_remove(struct mmc_host *host)
  */
 static void mmc_sd_detect(struct mmc_host *host)
 {
-       int err;
+       int err = 0;

        BUG_ON(!host);
        BUG_ON(!host->card);

        mmc_claim_host(host);

+       if (host->card->err_count >= ERR_TRIGGER_REINIT)
+               err = mmc_sd_init_card(host, host->ocr, host->card);
        /*
         * Just check if our card has been removed.
         */
-       err = mmc_send_status(host->card, NULL);
+       if (!err)
+               err = mmc_send_status(host->card, NULL);

        mmc_release_host(host);

diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 6b75250..178de17 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -143,6 +143,9 @@ struct mmc_card {
        const char              **info;         /* info strings */
        struct sdio_func_tuple  *tuples;        /* unknown common tuples */

+       unsigned int            err_count;
+#define ERR_TRIGGER_REINIT 1024
+
        struct dentry           *debugfs_root;
 };

diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index dd11ae5..3b979a1 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -122,6 +122,7 @@
 #define R1_UNDERRUN            (1 << 18)       /* ex, c */
 #define R1_OVERRUN             (1 << 17)       /* ex, c */
 #define R1_CID_CSD_OVERWRITE   (1 << 16)       /* erx, c, CID/CSD overwrite */
+#define R1_ERROR_MASK          0xffff0000
 #define R1_WP_ERASE_SKIP       (1 << 15)       /* sx, c */
 #define R1_CARD_ECC_DISABLED   (1 << 14)       /* sx, a */
 #define R1_ERASE_RESET         (1 << 13)       /* sr, c */
-- 
1.5.6.5
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