RE: [EXT] Re: [PATCH v5 1/2] mmc: Support kmsg dumper based on pstore/blk

[Bhaskara Budiredla]

[...]
>What patches are you referring to?

I was referring to this patch.
http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/pstore

Thanks,
Bhaskara

>-----Original Message-----
>From: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>Sent: Monday, June 7, 2021 4:47 PM
>To: Bhaskara Budiredla <bbudiredla@xxxxxxxxxxx>
>Cc: Kees Cook <keescook@xxxxxxxxxxxx>; Colin Cross
><ccross@xxxxxxxxxxx>; Tony Luck <tony.luck@xxxxxxxxx>; Sunil Kovvuri
>Goutham <sgoutham@xxxxxxxxxxx>; linux-mmc@xxxxxxxxxxxxxxx; Linux
>Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; linux-block <linux-
>block@xxxxxxxxxxxxxxx>; Jens Axboe <axboe@xxxxxxxxx>; Christoph Hellwig
><hch@xxxxxx>
>Subject: Re: [EXT] Re: [PATCH v5 1/2] mmc: Support kmsg dumper based on
>pstore/blk
>
>On Sat, 5 Jun 2021 at 12:31, Bhaskara Budiredla <bbudiredla@xxxxxxxxxxx>
>wrote:
>>
>> Hi Uffe,
>>
>> With due respect to pstore/blk subsystem changes we have been waiting
>since long time to see Christoph patches taken.
>
>What patches are you referring to?
>
>> But unfortunately it is still finding at that same stage only. Can you
>> please take up my patch in the current form (which is based on current
>> pstore/blk framework) instead of waiting indefinitely. If pstore/blk comes up
>with the changes that has been discussed by you previously, I will further
>submit the corresponding changes for eMMC devices.
>
>No, I am sorry, but that's not the way it works.
>
>If you really want to move things forward, I would suggest that you try to
>implement something along the lines of what I have suggested.
>Another option is to post an RFD/RFC so as solution can be discussed with the
>relevant people.
>
>Kind regards
>Uffe
>
>>
>> Thanks,
>> Bhaskara
>>
>> >-----Original Message-----
>> >From: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>> >Sent: Wednesday, January 20, 2021 8:36 PM
>> >To: Bhaskara Budiredla <bbudiredla@xxxxxxxxxxx>; Kees Cook
>> ><keescook@xxxxxxxxxxxx>
>> >Cc: Colin Cross <ccross@xxxxxxxxxxx>; Tony Luck
>> ><tony.luck@xxxxxxxxx>; Sunil Kovvuri Goutham <sgoutham@xxxxxxxxxxx>;
>> >linux- mmc@xxxxxxxxxxxxxxx; Linux Kernel Mailing List <linux-
>> >kernel@xxxxxxxxxxxxxxx>; linux-block <linux-block@xxxxxxxxxxxxxxx>;
>> >Jens Axboe <axboe@xxxxxxxxx>; Christoph Hellwig <hch@xxxxxx>
>> >Subject: [EXT] Re: [PATCH v5 1/2] mmc: Support kmsg dumper based on
>> >pstore/blk
>> >
>> >External Email
>> >
>> >---------------------------------------------------------------------
>> >-
>> >+ linux-block, Jens, Christoph
>> >
>> >On Wed, 20 Jan 2021 at 13:11, Bhaskara Budiredla
>> ><bbudiredla@xxxxxxxxxxx> wrote:
>> >>
>> >> This patch introduces to mmcpstore. The functioning of mmcpstore is
>> >> similar to mtdpstore. mmcpstore works on FTL based flash devices
>> >> whereas mtdpstore works on raw flash devices. When the system
>> >> crashes, mmcpstore stores the kmsg panic and oops logs to a user
>> >> specified MMC device.
>> >>
>> >> It collects the details about the host MMC device through
>> >> pstore/blk "blkdev" parameter. The user can specify the MMC device
>> >> in many ways by checking in Documentation/admin-guide/pstore-blk.rst.
>> >>
>> >> The individual mmc host drivers have to define suitable polling and
>> >> cleanup subroutines to write kmsg panic/oops logs through mmcpstore.
>> >> These new host operations are needed as pstore panic write runs
>> >> with interrupts disabled.
>> >
>> >Okay, let me again try to clarify on how I see this to move this forward.
>> >
>> >1)
>> >In my opinion, pstore shouldn't be using callbacks for *regular* I/O
>> >read/writes. It's upside-down of how the storage stack is designed to work.
>> >
>> >Instead, pstore should be implemented as a regular filesystem, that
>> >can be mounted on top of a regular block device partition. In this
>> >way, the lower layer block device drivers (as mmc), don't need
>> >special support for pstore, the regular I/O block read/write path will just
>work as is.
>> >
>> >2)
>> >When it comes to supporting *panic* writes for pstore, things become
>> >a bit more complicated. For sure some adaptations are needed in each
>> >block device driver to support this.
>> >
>> >However, the current method means relying on the lower level block
>> >device driver to figure out the pstore partition. Based on that, it
>> >should then register itself for pstore support and hook up callbacks
>> >for the corresponding block device driver instance, at least that is
>> >what it looks like to me. Again, I think this is upside-down from the
>> >storage stack perspective. The partition to use for pstore, should be based
>upon its file system mount point.
>> >
>> >Furthermore, I think the responsibility for lower layer block device
>> >drivers should instead be to just "register/announce" themselves as
>> >capable of supporting "panic writes", if they can. Exactly how to
>> >best do this, probably needs to be discussed further with the block
>> >device people, I think. I have looped in Jens and Christoph, perhaps they
>can share their opinion in this.
>> >
>> >That said, it looks to me that pstore needs more work before it's
>> >ready to be adopted for generic support in block device drivers.
>> >
>> >Kind regards
>> >Uffe
>> >
>> >>
>> >> Signed-off-by: Bhaskara Budiredla <bbudiredla@xxxxxxxxxxx>
>> >> ---
>> >>  drivers/mmc/core/Kconfig     |  14 ++-
>> >>  drivers/mmc/core/Makefile    |   1 +
>> >>  drivers/mmc/core/block.c     |  19 +++
>> >>  drivers/mmc/core/block.h     |   9 ++
>> >>  drivers/mmc/core/core.c      |  44 +++++++
>> >>  drivers/mmc/core/mmcpstore.c | 227
>> >+++++++++++++++++++++++++++++++++++
>> >>  include/linux/mmc/core.h     |   5 +
>> >>  include/linux/mmc/host.h     |  12 ++
>> >>  8 files changed, 330 insertions(+), 1 deletion(-)  create mode
>> >> 100644 drivers/mmc/core/mmcpstore.c
>> >>
>> >> diff --git a/drivers/mmc/core/Kconfig b/drivers/mmc/core/Kconfig
>> >> index
>> >> c12fe13e4b14..4c651da4f2d2 100644
>> >> --- a/drivers/mmc/core/Kconfig
>> >> +++ b/drivers/mmc/core/Kconfig
>> >> @@ -34,9 +34,22 @@ config PWRSEQ_SIMPLE
>> >>           This driver can also be built as a module. If so, the module
>> >>           will be called pwrseq_simple.
>> >>
>> >> +config MMC_PSTORE_BACKEND
>> >> +       bool "Log panic/oops to a MMC buffer"
>> >> +       depends on MMC_BLOCK
>> >> +       help
>> >> +         This option will let you create platform backend to store kmsg
>> >> +         crash dumps to a user specified MMC device. This is primarily
>> >> +         based on pstore/blk.
>> >> +
>> >> +config MMC_PSTORE
>> >> +       tristate
>> >> +       select PSTORE_BLK
>> >> +
>> >>  config MMC_BLOCK
>> >>         tristate "MMC block device driver"
>> >>         depends on BLOCK
>> >> +       select MMC_PSTORE if MMC_PSTORE_BACKEND=y
>> >>         default y
>> >>         help
>> >>           Say Y here to enable the MMC block device driver support.
>> >> @@ -80,4 +93,3 @@ config MMC_TEST
>> >>
>> >>           This driver is only of interest to those developing or
>> >>           testing a host driver. Most people should say N here.
>> >> -
>> >> diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
>> >> index 95ffe008ebdf..7cb9a3af4827 100644
>> >> --- a/drivers/mmc/core/Makefile
>> >> +++ b/drivers/mmc/core/Makefile
>> >> @@ -16,5 +16,6 @@ obj-$(CONFIG_PWRSEQ_EMMC)     +=
>pwrseq_emmc.o
>> >>  mmc_core-$(CONFIG_DEBUG_FS)    += debugfs.o
>> >>  obj-$(CONFIG_MMC_BLOCK)                += mmc_block.o
>> >>  mmc_block-objs                 := block.o queue.o
>> >> +mmc_block-$(CONFIG_MMC_PSTORE) += mmcpstore.o
>> >>  obj-$(CONFIG_MMC_TEST)         += mmc_test.o
>> >>  obj-$(CONFIG_SDIO_UART)                += sdio_uart.o
>> >> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
>> >> index
>> >> 42e27a298218..6592722cd7b2 100644
>> >> --- a/drivers/mmc/core/block.c
>> >> +++ b/drivers/mmc/core/block.c
>> >> @@ -2870,6 +2870,21 @@ static void mmc_blk_remove_debugfs(struct
>> >> mmc_card *card,
>> >>
>> >>  #endif /* CONFIG_DEBUG_FS */
>> >>
>> >> +#if IS_ENABLED(CONFIG_MMC_PSTORE)
>> >> +sector_t mmc_blk_get_part(struct mmc_card *card, int part_num,
>> >> +sector_t *size) {
>> >> +       struct mmc_blk_data *md = dev_get_drvdata(&card->dev);
>> >> +       struct gendisk *disk = md->disk;
>> >> +       struct disk_part_tbl *part_tbl = disk->part_tbl;
>> >> +
>> >> +       if (part_num < 0 || part_num >= part_tbl->len)
>> >> +               return 0;
>> >> +
>> >> +       *size = part_tbl->part[part_num]->nr_sects << SECTOR_SHIFT;
>> >> +       return part_tbl->part[part_num]->start_sect;
>> >> +}
>> >> +#endif
>> >> +
>> >>  static int mmc_blk_probe(struct mmc_card *card)  {
>> >>         struct mmc_blk_data *md, *part_md; @@ -2913,6 +2928,9 @@
>> >> static int mmc_blk_probe(struct mmc_card *card)
>> >>                         goto out;
>> >>         }
>> >>
>> >> +       if (mmc_card_mmc(card) || mmc_card_sd(card))
>> >> +               mmcpstore_card_set(card, md->disk->disk_name);
>> >> +
>> >>         /* Add two debugfs entries */
>> >>         mmc_blk_add_debugfs(card, md);
>> >>
>> >> @@ -3060,6 +3078,7 @@ static void __exit mmc_blk_exit(void)
>> >>         unregister_blkdev(MMC_BLOCK_MAJOR, "mmc");
>> >>         unregister_chrdev_region(mmc_rpmb_devt, MAX_DEVICES);
>> >>         bus_unregister(&mmc_rpmb_bus_type);
>> >> +       unregister_mmcpstore();
>> >>  }
>> >>
>> >>  module_init(mmc_blk_init);
>> >> diff --git a/drivers/mmc/core/block.h b/drivers/mmc/core/block.h
>> >> index
>> >> 31153f656f41..2a4ee5568194 100644
>> >> --- a/drivers/mmc/core/block.h
>> >> +++ b/drivers/mmc/core/block.h
>> >> @@ -16,5 +16,14 @@ void mmc_blk_mq_recovery(struct mmc_queue
>> >*mq);
>> >> struct work_struct;
>> >>
>> >>  void mmc_blk_mq_complete_work(struct work_struct *work);
>> >> +#if IS_ENABLED(CONFIG_MMC_PSTORE)
>> >> +sector_t mmc_blk_get_part(struct mmc_card *card, int part_num,
>> >> +sector_t *size); void mmcpstore_card_set(struct mmc_card *card,
>> >> +const char *disk_name); void unregister_mmcpstore(void); #else
>> >> +static inline void mmcpstore_card_set(struct mmc_card *card,
>> >> +                                       const char *disk_name) {}
>> >> +static inline void unregister_mmcpstore(void) {} #endif
>> >>
>> >>  #endif
>> >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> >> index 19f1ee57fb34..7ad7ff1cab8c 100644
>> >> --- a/drivers/mmc/core/core.c
>> >> +++ b/drivers/mmc/core/core.c
>> >> @@ -569,6 +569,30 @@ int mmc_cqe_recovery(struct mmc_host *host)
>}
>> >> EXPORT_SYMBOL(mmc_cqe_recovery);
>> >>
>> >> +#if IS_ENABLED(CONFIG_MMC_PSTORE)
>> >> +/**
>> >> + *     mmc_wait_for_pstore_req - initiate a blocking mmc request
>> >> + *     @host: MMC host to start command
>> >> + *     @mrq: MMC request to start
>> >> + *
>> >> + *     Start a blocking MMC request for a host and wait for the request
>> >> + *     to complete that is based on polling and timeout.
>> >> + */
>> >> +void mmc_wait_for_pstore_req(struct mmc_host *host, struct
>> >> +mmc_request *mrq) {
>> >> +       unsigned int timeout;
>> >> +
>> >> +       host->ops->req_cleanup_pending(host);
>> >> +       mmc_start_request(host, mrq);
>> >> +
>> >> +       if (mrq->data) {
>> >> +               timeout = mrq->data->timeout_ns / NSEC_PER_MSEC;
>> >> +               host->ops->req_completion_poll(host, timeout);
>> >> +       }
>> >> +}
>> >> +EXPORT_SYMBOL(mmc_wait_for_pstore_req);
>> >> +#endif
>> >> +
>> >>  /**
>> >>   *     mmc_is_req_done - Determine if a 'cap_cmd_during_tfr' request is
>> >done
>> >>   *     @host: MMC host
>> >> @@ -817,6 +841,26 @@ int __mmc_claim_host(struct mmc_host *host,
>> >> struct mmc_ctx *ctx,  }  EXPORT_SYMBOL(__mmc_claim_host);
>> >>
>> >> +#if IS_ENABLED(CONFIG_MMC_PSTORE)
>> >> +/**
>> >> + *     mmc_claim_host_async - claim host in atomic context
>> >> + *     @host: mmc host to claim
>> >> + *
>> >> + *     This routine may be called in panic/oops scenarios.
>> >> + *     Return zero with host claim success, else busy status.
>> >> + */
>> >> +int mmc_claim_host_async(struct mmc_host *host) {
>> >> +       if (!host->claimed && pm_runtime_active(mmc_dev(host))) {
>> >> +               host->claimed = 1;
>> >> +               return 0;
>> >> +       }
>> >> +
>> >> +       return -EBUSY;
>> >> +}
>> >> +EXPORT_SYMBOL(mmc_claim_host_async);
>> >> +#endif
>> >> +
>> >>  /**
>> >>   *     mmc_release_host - release a host
>> >>   *     @host: mmc host to release
>> >> diff --git a/drivers/mmc/core/mmcpstore.c
>> >> b/drivers/mmc/core/mmcpstore.c new file mode 100644 index
>> >> 000000000000..f783ea215f18
>> >> --- /dev/null
>> >> +++ b/drivers/mmc/core/mmcpstore.c
>> >> @@ -0,0 +1,227 @@
>> >> +// SPDX-License-Identifier: GPL-2.0
>> >> +/*
>> >> + * MMC pstore support based on pstore/blk
>> >> + *
>> >> + * Copyright (c) 2020 Marvell.
>> >> + * Author: Bhaskara Budiredla <bbudiredla@xxxxxxxxxxx>  */
>> >> +
>> >> +#define pr_fmt(fmt) "mmcpstore: " fmt
>> >> +
>> >> +#include <linux/kernel.h>
>> >> +#include <linux/module.h>
>> >> +#include <linux/pstore_blk.h>
>> >> +#include <linux/blkdev.h>
>> >> +#include <linux/mount.h>
>> >> +#include <linux/slab.h>
>> >> +#include <linux/mmc/mmc.h>
>> >> +#include <linux/mmc/host.h>
>> >> +#include <linux/mmc/card.h>
>> >> +#include <linux/scatterlist.h>
>> >> +#include "block.h"
>> >> +#include "card.h"
>> >> +#include "core.h"
>> >> +
>> >> +static struct mmcpstore_context {
>> >> +       char dev_name[BDEVNAME_SIZE];
>> >> +       int partno;
>> >> +       sector_t start_sect;
>> >> +       sector_t size;
>> >> +       struct pstore_blk_config conf;
>> >> +       struct pstore_blk_info info;
>> >> +
>> >> +       struct mmc_card *card;
>> >> +       struct mmc_request *mrq;
>> >> +} oops_cxt;
>> >> +
>> >> +static void mmc_prep_req(struct mmc_request *mrq,
>> >> +               unsigned int sect_offset, unsigned int nsects,
>> >> +               struct scatterlist *sg, u32 opcode, unsigned int
>> >> +flags) {
>> >> +       mrq->cmd->opcode = opcode;
>> >> +       mrq->cmd->arg = sect_offset;
>> >> +       mrq->cmd->flags = MMC_RSP_R1 | MMC_CMD_ADTC;
>> >> +
>> >> +       if (nsects == 1) {
>> >> +               mrq->stop = NULL;
>> >> +       } else {
>> >> +               mrq->stop->opcode = MMC_STOP_TRANSMISSION;
>> >> +               mrq->stop->arg = 0;
>> >> +               mrq->stop->flags = MMC_RSP_R1B | MMC_CMD_AC;
>> >> +       }
>> >> +
>> >> +       mrq->data->blksz = SECTOR_SIZE;
>> >> +       mrq->data->blocks = nsects;
>> >> +       mrq->data->flags = flags;
>> >> +       mrq->data->sg = sg;
>> >> +       mrq->data->sg_len = 1;
>> >> +}
>> >> +
>> >> +static int mmcpstore_panic_write_req(const char *buf,
>> >> +               unsigned int nsects, unsigned int sect_offset) {
>> >> +       struct mmcpstore_context *cxt = &oops_cxt;
>> >> +       struct mmc_request *mrq = cxt->mrq;
>> >> +       struct mmc_card *card = cxt->card;
>> >> +       struct mmc_host *host = card->host;
>> >> +       struct scatterlist sg;
>> >> +       u32 opcode;
>> >> +       int ret;
>> >> +
>> >> +       opcode = (nsects > 1) ? MMC_WRITE_MULTIPLE_BLOCK :
>> >MMC_WRITE_BLOCK;
>> >> +       mmc_prep_req(mrq, sect_offset, nsects, &sg, opcode,
>> >MMC_DATA_WRITE);
>> >> +       sg_init_one(&sg, buf, (nsects << SECTOR_SHIFT));
>> >> +       mmc_set_data_timeout(mrq->data, cxt->card);
>> >> +
>> >> +       ret = mmc_claim_host_async(host);
>> >> +       if (ret)
>> >> +               return ret;
>> >> +
>> >> +       mmc_wait_for_pstore_req(host, mrq);
>> >> +       return 0;
>> >> +}
>> >> +
>> >> +static int mmcpstore_panic_write(const char *buf, sector_t off,
>> >> +sector_t sects) {
>> >> +       struct mmcpstore_context *cxt = &oops_cxt;
>> >> +       int ret;
>> >> +
>> >> +       ret = mmcpstore_panic_write_req(buf, sects, cxt->start_sect + off);
>> >> +       if (ret)
>> >> +               return ret;
>> >> +
>> >> +       return 0;
>> >> +}
>> >> +
>> >> +static struct block_device *mmcpstore_open_backend(const char
>> >> +*device) {
>> >> +       struct block_device *bdev;
>> >> +       dev_t devt;
>> >> +
>> >> +       bdev = blkdev_get_by_path(device, FMODE_READ, NULL);
>> >> +       if (IS_ERR(bdev)) {
>> >> +               devt = name_to_dev_t(device);
>> >> +               if (devt == 0)
>> >> +                       return ERR_PTR(-ENODEV);
>> >> +
>> >> +               bdev = blkdev_get_by_dev(devt, FMODE_READ, NULL);
>> >> +               if (IS_ERR(bdev))
>> >> +                       return bdev;
>> >> +       }
>> >> +
>> >> +       return bdev;
>> >> +}
>> >> +
>> >> +static void mmcpstore_close_backend(struct block_device *bdev) {
>> >> +       if (!bdev)
>> >> +               return;
>> >> +       blkdev_put(bdev, FMODE_READ); }
>> >> +
>> >> +void mmcpstore_card_set(struct mmc_card *card, const char
>> >> +*disk_name) {
>> >> +       struct mmcpstore_context *cxt = &oops_cxt;
>> >> +       struct pstore_blk_config *conf = &cxt->conf;
>> >> +       struct pstore_blk_info *info = &cxt->info;
>> >> +       struct block_device *bdev;
>> >> +       struct mmc_command *stop;
>> >> +       struct mmc_command *cmd;
>> >> +       struct mmc_request *mrq;
>> >> +       struct mmc_data *data;
>> >> +       int ret;
>> >> +
>> >> +       ret = pstore_blk_get_config(conf);
>> >> +       if (!conf->device[0]) {
>> >> +               pr_debug("psblk backend is empty\n");
>> >> +               return;
>> >> +       }
>> >> +
>> >> +       /* Multiple backend devices not allowed */
>> >> +       if (cxt->dev_name[0])
>> >> +               return;
>> >> +
>> >> +       bdev =  mmcpstore_open_backend(conf->device);
>> >> +       if (IS_ERR(bdev)) {
>> >> +               pr_err("%s failed to open with %ld\n",
>> >> +                               conf->device, PTR_ERR(bdev));
>> >> +               return;
>> >> +       }
>> >> +
>> >> +       bdevname(bdev, cxt->dev_name);
>> >> +       cxt->partno = bdev->bd_part->partno;
>> >> +       mmcpstore_close_backend(bdev);
>> >> +
>> >> +       if (strncmp(cxt->dev_name, disk_name, strlen(disk_name)))
>> >> +               return;
>> >> +
>> >> +       cxt->start_sect = mmc_blk_get_part(card, cxt->partno, &cxt->size);
>> >> +       if (!cxt->start_sect) {
>> >> +               pr_err("Non-existent partition %d selected\n", cxt->partno);
>> >> +               return;
>> >> +       }
>> >> +
>> >> +       /* Check for host mmc panic write polling function definitions */
>> >> +       if (!card->host->ops->req_cleanup_pending ||
>> >> +                       !card->host->ops->req_completion_poll)
>> >> +               return;
>> >> +
>> >> +       cxt->card = card;
>> >> +
>> >> +       mrq = kzalloc(sizeof(struct mmc_request), GFP_KERNEL);
>> >> +       if (!mrq)
>> >> +               goto out;
>> >> +
>> >> +       cmd = kzalloc(sizeof(struct mmc_command), GFP_KERNEL);
>> >> +       if (!cmd)
>> >> +               goto free_mrq;
>> >> +
>> >> +       stop = kzalloc(sizeof(struct mmc_command), GFP_KERNEL);
>> >> +       if (!stop)
>> >> +               goto free_cmd;
>> >> +
>> >> +       data = kzalloc(sizeof(struct mmc_data), GFP_KERNEL);
>> >> +       if (!data)
>> >> +               goto free_stop;
>> >> +
>> >> +       mrq->cmd = cmd;
>> >> +       mrq->data = data;
>> >> +       mrq->stop = stop;
>> >> +       cxt->mrq = mrq;
>> >> +
>> >> +       info->major = MMC_BLOCK_MAJOR;
>> >> +       info->flags = PSTORE_FLAGS_DMESG;
>> >> +       info->panic_write = mmcpstore_panic_write;
>> >> +       ret = register_pstore_blk(info);
>> >> +       if (ret) {
>> >> +               pr_err("%s registering with psblk failed (%d)\n",
>> >> +                               cxt->dev_name, ret);
>> >> +               goto free_data;
>> >> +       }
>> >> +
>> >> +       pr_info("%s registered as psblk backend\n", cxt->dev_name);
>> >> +       return;
>> >> +
>> >> +free_data:
>> >> +       kfree(data);
>> >> +free_stop:
>> >> +       kfree(stop);
>> >> +free_cmd:
>> >> +       kfree(cmd);
>> >> +free_mrq:
>> >> +       kfree(mrq);
>> >> +out:
>> >> +       return;
>> >> +}
>> >> +
>> >> +void unregister_mmcpstore(void)
>> >> +{
>> >> +       struct mmcpstore_context *cxt = &oops_cxt;
>> >> +
>> >> +       unregister_pstore_blk(MMC_BLOCK_MAJOR);
>> >> +       kfree(cxt->mrq->data);
>> >> +       kfree(cxt->mrq->stop);
>> >> +       kfree(cxt->mrq->cmd);
>> >> +       kfree(cxt->mrq);
>> >> +       cxt->card = NULL;
>> >> +}
>> >> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
>> >> index 29aa50711626..53840a361b5a 100644
>> >> --- a/include/linux/mmc/core.h
>> >> +++ b/include/linux/mmc/core.h
>> >> @@ -166,6 +166,11 @@ struct mmc_request {
>> >>
>> >>  struct mmc_card;
>> >>
>> >> +#if IS_ENABLED(CONFIG_MMC_PSTORE)
>> >> +void mmc_wait_for_pstore_req(struct mmc_host *host, struct
>> >> +mmc_request *mrq); int mmc_claim_host_async(struct mmc_host
>> >> +*host); #endif
>> >> +
>> >>  void mmc_wait_for_req(struct mmc_host *host, struct mmc_request
>> >> *mrq);  int mmc_wait_for_cmd(struct mmc_host *host, struct
>> >mmc_command *cmd,
>> >>                 int retries);
>> >> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> >> index
>> >> 01bba36545c5..ba9001498e03 100644
>> >> --- a/include/linux/mmc/host.h
>> >> +++ b/include/linux/mmc/host.h
>> >> @@ -178,6 +178,18 @@ struct mmc_host_ops {
>> >>
>> >>         /* Initialize an SD express card, mandatory for MMC_CAP2_SD_EXP.
>*/
>> >>         int     (*init_sd_express)(struct mmc_host *host, struct mmc_ios
>*ios);
>> >> +
>> >> +#if IS_ENABLED(CONFIG_MMC_PSTORE)
>> >> +       /*
>> >> +        * The following two APIs are introduced to support mmcpstore
>> >> +        * functionality. Cleanup API to terminate the ongoing and
>> >> +        * pending requests before a panic write post, and polling API
>> >> +        * to ensure that write succeeds before the Kernel dies.
>> >> +        */
>> >> +       void    (*req_cleanup_pending)(struct mmc_host *host);
>> >> +       int     (*req_completion_poll)(struct mmc_host *host,
>> >> +                                      unsigned long timeout);
>> >> +#endif
>> >>  };
>> >>
>> >>  struct mmc_cqe_ops {
>> >> --
>> >> 2.17.1
>> >>