Message-ID: <CY4PR1801MB2070025916414D8161C09864DE389@CY4PR1801MB2070.namprd18.prod.outlook.com>
Date:   Mon, 7 Jun 2021 16:28:22 +0000
From:   Bhaskara Budiredla <bbudiredla@...vell.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Kees Cook <keescook@...omium.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Sunil Kovvuri Goutham <sgoutham@...vell.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>
Subject: RE: [EXT] Re: [PATCH v5 1/2] mmc: Support kmsg dumper based on
 pstore/blk

Hi Christoph,

Could you please share the current state of your work @https://urldefense.proofpoint.com/v2/url?u=http-3A__git.infradead.org_
and provide some direction on Uffe's comments?

Thanks,
Bhaskara


>-----Original Message-----
>From: Ulf Hansson <ulf.hansson@...aro.org>
>Sent: Monday, June 7, 2021 7:38 PM
>To: Bhaskara Budiredla <bbudiredla@...vell.com>
>Cc: Kees Cook <keescook@...omium.org>; Colin Cross
><ccross@...roid.com>; Tony Luck <tony.luck@...el.com>; Sunil Kovvuri
>Goutham <sgoutham@...vell.com>; linux-mmc@...r.kernel.org; Linux
>Kernel Mailing List <linux-kernel@...r.kernel.org>; linux-block <linux-
>block@...r.kernel.org>; Jens Axboe <axboe@...nel.dk>; Christoph Hellwig
><hch@....de>
>Subject: Re: [EXT] Re: [PATCH v5 1/2] mmc: Support kmsg dumper based on
>pstore/blk
>
>On Mon, 7 Jun 2021 at 14:37, Bhaskara Budiredla <bbudiredla@...vell.com>
>wrote:
>>
>> [...]
>> >What patches are you referring to?
>>
>> I was referring to this patch.
>> https://urldefense.proofpoint.com/v2/url?u=http-3A__git.infradead.org_
>>
>users_hch_misc.git_shortlog_refs_heads_pstore&d=DwIBaQ&c=nKjWec2b6R0
>mO
>>
>yPaz7xtfQ&r=9P_lSljSO7KnQNkCGsgu9x_Op4mstSdqWN3Olr4bUv0&m=fl42xU
>Yo4DOO
>> I8uNNOE4Av-fan25pMik8lX5H4G0694&s=tTmGbewO2pg-
>_9D0vAb_GNucJuZAjJCFkuSz
>> 6whJGho&e=
>
>Alright. I didn't know about these, thanks for the pointer. Looks like a big step
>in the right direction.
>
>I guess Christoph simply has been busy with other things. Perhaps you should
>ask if you can help and pick up from where he left the series?
>
>Kind regards
>Uffe
>
>>
>> Thanks,
>> Bhaskara
>>
>> >-----Original Message-----
>> >From: Ulf Hansson <ulf.hansson@...aro.org>
>> >Sent: Monday, June 7, 2021 4:47 PM
>> >To: Bhaskara Budiredla <bbudiredla@...vell.com>
>> >Cc: Kees Cook <keescook@...omium.org>; Colin Cross
>> ><ccross@...roid.com>; Tony Luck <tony.luck@...el.com>; Sunil Kovvuri
>> >Goutham <sgoutham@...vell.com>; linux-mmc@...r.kernel.org; Linux
>> >Kernel Mailing List <linux-kernel@...r.kernel.org>; linux-block
>> ><linux- block@...r.kernel.org>; Jens Axboe <axboe@...nel.dk>;
>> >Christoph Hellwig <hch@....de>
>> >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@...vell.com>
>> >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@...aro.org>
>> >> >Sent: Wednesday, January 20, 2021 8:36 PM
>> >> >To: Bhaskara Budiredla <bbudiredla@...vell.com>; Kees Cook
>> >> ><keescook@...omium.org>
>> >> >Cc: Colin Cross <ccross@...roid.com>; Tony Luck
>> >> ><tony.luck@...el.com>; Sunil Kovvuri Goutham
>> >> ><sgoutham@...vell.com>;
>> >> >linux- mmc@...r.kernel.org; Linux Kernel Mailing List <linux-
>> >> >kernel@...r.kernel.org>; linux-block
>> >> ><linux-block@...r.kernel.org>; Jens Axboe <axboe@...nel.dk>;
>> >> >Christoph Hellwig <hch@....de>
>> >> >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@...vell.com> 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@...vell.com>
>> >> >> ---
>> >> >>  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@...vell.com>  */
>> >> >> +
>> >> >> +#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
>> >> >>

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