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mmc: Fix MMC request issuing race condition to prevent stall #7486

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mmc: Fix MMC request issuing race condition to prevent stall #7486

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9 changes: 6 additions & 3 deletions drivers/mmc/core/queue.c
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Original file line number Diff line number Diff line change
Expand Up @@ -243,13 +243,15 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
enum mmc_issued issued;
bool get_card, cqe_retune_ok;
blk_status_t ret;
bool write;

if (mmc_card_removed(mq->card)) {
req->rq_flags |= RQF_QUIET;
return BLK_STS_IOERR;
}

issue_type = mmc_issue_type(mq, req);
write = req_op(req) == REQ_OP_WRITE;

spin_lock_irq(&mq->lock);

Expand All @@ -271,7 +273,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
spin_unlock_irq(&mq->lock);
return BLK_STS_RESOURCE;
}
if (!host->hsq_enabled && host->cqe_enabled && req_op(req) == REQ_OP_WRITE &&
if (!host->hsq_enabled && host->cqe_enabled && write &&
mq->pending_writes >= card->max_posted_writes) {
spin_unlock_irq(&mq->lock);
return BLK_STS_RESOURCE;
Expand All @@ -292,7 +294,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
/* Parallel dispatch of requests is not supported at the moment */
mq->busy = true;

if (req_op(req) == REQ_OP_WRITE)
if (write)
mq->pending_writes++;
mq->in_flight[issue_type] += 1;
get_card = (mmc_tot_in_flight(mq) == 1);
Expand Down Expand Up @@ -333,7 +335,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
bool put_card = false;

spin_lock_irq(&mq->lock);
if (req_op(req) == REQ_OP_WRITE)
if (write)
mq->pending_writes--;
mq->in_flight[issue_type] -= 1;
if (mmc_tot_in_flight(mq) == 0)
Expand All @@ -345,6 +347,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
} else {
WRITE_ONCE(mq->busy, false);
}
WARN_ON_ONCE(mq->pending_writes < 0);

return ret;
}
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2 changes: 1 addition & 1 deletion include/linux/mmc/card.h
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Original file line number Diff line number Diff line change
Expand Up @@ -384,7 +384,7 @@ struct mmc_card {

struct workqueue_struct *complete_wq; /* Private workqueue */

unsigned int max_posted_writes; /* command queue posted write limit */
int max_posted_writes; /* command queue posted write limit */
};

static inline bool mmc_large_sector(struct mmc_card *card)
Expand Down
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