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Subject: Re: panic with CONFIG_FAIL_MMC_REQUEST and cqhci
To:     Laura Abbott <labbott@redhat.com>,
        Ulf Hansson <ulf.hansson@linaro.org>
Cc:     Adrian Hunter <adrian.hunter@intel.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-mmc@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Asutosh Das <asutoshd@codeaurora.org>
References: <d220878f-2981-5e5e-22b0-5534cc037e8d@redhat.com>
From:   Ritesh Harjani <riteshh@codeaurora.org>
Message-ID: <5e81d594-15bb-81f5-75a0-a147fd5cfc18@codeaurora.org>
Date:   Fri, 22 Feb 2019 19:12:16 +0530
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Hi Laura,

On 2/19/2019 12:59 AM, Laura Abbott wrote:
> Hi,
>
> Fedora got report of a panic when I accidentally left debugging enabled
> on a build https://bugzilla.redhat.com/show_bug.cgi?id=1677438
>
> It looks like a panic from code in CONFIG_FAIL_MMC_REQUEST from the
> cqhci driver because there isn't a command (high level overview)

With CQHCI, in case of non-DCMD (data) requests, mrq->cmd can be NULL.
Is this crash happening always (100% on bootup) with CQHCI & 
CONFIG_FAIL_MMC_REQUEST enabled?

Sure, I will role out a patch to handle this case.
It will be great, if you could also confirm it from your side.

Regards
Ritesh


>
> (gdb) list *(mmc_should_fail_request+0xa)
> 0x149a is in mmc_should_fail_request (drivers/mmc/core/core.c:98).
> 93        };
> 94
> 95        if (!data)
> 96            return;
> 97
> 98        if (cmd->error || data->error ||
> 99            !should_fail(&host->fail_mmc_request, data->blksz * 
> data->blocks))
> 100            return;
> 101
> 102        data->error = data_errors[prandom_u32() % 
> ARRAY_SIZE(data_errors)];
> (gdb)
>
> (gdb) list *(mmc_cqe_request_done+0x1c)
> 0x2a6c is in mmc_cqe_request_done (drivers/mmc/core/core.c:505).
> 500    void mmc_cqe_request_done(struct mmc_host *host, struct 
> mmc_request *mrq)
> 501    {
> 502        mmc_should_fail_request(host, mrq);
> 503
> 504        /* Flag re-tuning needed on CRC errors */
> 505        if ((mrq->cmd && mrq->cmd->error == -EILSEQ) ||
> 506            (mrq->data && mrq->data->error == -EILSEQ))
> 507            mmc_retune_needed(host);
> 508
> 509        trace_mmc_request_done(host, mrq);
>
>
> (gdb) list *(cqhci_irq+0x1d2)
> 0x1172 is in cqhci_irq (drivers/mmc/host/cqhci.c:747).
> 742                data->bytes_xfered = 0;
> 743            else
> 744                data->bytes_xfered = data->blksz * data->blocks;
> 745        }
> 746
> 747        mmc_cqe_request_done(mmc, mrq);
> 748    }
> 749
> 750    irqreturn_t cqhci_irq(struct mmc_host *mmc, u32 intmask, int 
> cmd_error,
> 751                  int data_error)
>
> This can be worked around by turning off the option but it
> seems like something to fix up.
>
> Thanks,
> Laura