linux-kernel - [PATCH] mmc: block: Prevent new req entering queue while freeing up the queue

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Date:   Wed, 28 Oct 2020 16:49:42 +0530
From:   Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
To:     adrian.hunter@...el.com, ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Veerabhadrarao Badiganti <vbadigan@...eaurora.org>,
        Jens Axboe <axboe@...nel.dk>,
        Baolin Wang <baolin.wang@...aro.org>,
        Chaotian Jing <chaotian.jing@...iatek.com>,
        Peng Hao <richard.peng@...o.com>
Subject: [PATCH] mmc: block: Prevent new req entering queue while freeing up the queue

The commit bbdc74dc19e0 ("mmc: block: Prevent new req entering queue
after its cleanup") has introduced this change but it got moved after
del_gendisk() with commit 57678e5a3d51 ("mmc: block: Delete gendisk
before cleaning up the request queue").

It is blocking reboot with below Call stack().

INFO: task reboot:3086 blocked for more than 122 seconds.
     __schedule
     schedule
     schedule_timeout
     io_schedule_timeout
     do_wait_for_common
     wait_for_completion_io
     submit_bio_wait
     blkdev_issue_flush
     ext4_sync_fs
     __sync_filesystem
     sync_filesystem
     fsync_bdev
     invalidate_partition
     del_gendisk
     mmc_blk_remove_req
     mmc_blk_remove
     mmc_bus_remove
     device_release_driver_internal
     device_release_driver
     bus_remove_device
     device_del
     mmc_remove_card
     mmc_remove
     mmc_stop_host
     mmc_remove_host
     sdhci_remove_host
     sdhci_msm_remove
     sdhci_msm_shutdown
     platform_drv_shutdown
     device_shutdown
     kernel_restart_prepare
     kernel_restart

So bringing this change back.

Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
---

I'm observing this issue 100% of the time with shutdown callback added to sdhci-msm driver.
I'm trying on 5.4 kernel with ChromeOS.

Please let me know if this can be fixed in a better way.
---

 drivers/mmc/core/block.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 8d3df0be0355..76dbb2b8a13b 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2627,6 +2627,7 @@ static void mmc_blk_remove_req(struct mmc_blk_data *md)
 		 * from being accepted.
 		 */
 		card = md->queue.card;
+		blk_set_queue_dying(md->queue.queue);
 		if (md->disk->flags & GENHD_FL_UP) {
 			device_remove_file(disk_to_dev(md->disk), &md->force_ro);
 			if ((md->area_type & MMC_BLK_DATA_AREA_BOOT) &&
-- 
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