netdev - Re: Issue with Broadcom wireless in 5.2rc1 (was Re: [PATCH] mmc: sdhci: queue work after sdhci_defer

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Message-ID: <CAPDyKFrm=NTKjsEPiwzUVbDDzjW5PwZteXbKtPUi9GTUB4kbMQ@mail.gmail.com>
Date:   Tue, 28 May 2019 22:11:55 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Brian Masney <masneyb@...tation.org>,
        Adrian Hunter <adrian.hunter@...el.com>
Cc:     Arend Van Spriel <arend.vanspriel@...adcom.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>,
        Faiz Abbas <faiz_abbas@...com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, netdev@...r.kernel.org
Subject: Re: Issue with Broadcom wireless in 5.2rc1 (was Re: [PATCH] mmc:
 sdhci: queue work after sdhci_defer_done())

On Mon, 27 May 2019 at 14:50, Brian Masney <masneyb@...tation.org> wrote:
>
> On Mon, May 27, 2019 at 03:08:07PM +0300, Adrian Hunter wrote:
> > On 27/05/19 12:37 PM, Brian Masney wrote:
> > > On Sun, May 26, 2019 at 03:58:19PM -0400, Brian Masney wrote:
> > >> I attached a patch that shows how I was able to determine what had
> > >> already claimed the host.
> > > On Mon, May 27, 2019 at 10:48:24AM +0300, Adrian Hunter wrote:
> > >> This is because SDHCI is using the IRQ thread to process the SDIO card
> > >> interrupt (sdio_run_irqs()).  When the card driver tries to use the card, it
> > >> causes interrupts which deadlocks since c07a48c26519 ("mmc: sdhci: Remove
> > >> finish_tasklet") has moved the tasklet processing to the IRQ thread.
> > >>
> > >> I would expect to be able to use the IRQ thread to complete requests, and it
> > >> is desirable to do so because it is lower latency.
> > >>
> > >> Probably, SDHCI should use sdio_signal_irq() which queues a work item, and
> > >> is what other drivers are doing.
> > >>
> > >> I will investigate some more and send a patch.
> >
> > Please try the patch below:
> >
> > From: Adrian Hunter <adrian.hunter@...el.com>
> > Date: Mon, 27 May 2019 14:45:55 +0300
> > Subject: [PATCH] mmc: sdhci: Fix SDIO IRQ thread deadlock
> >
> > Since commit c07a48c26519 ("mmc: sdhci: Remove finish_tasklet"), the IRQ
> > thread might be used to complete requests, but the IRQ thread is also used
> > to process SDIO card interrupts. This can cause a deadlock when the SDIO
> > processing tries to access the card since that would also require the IRQ
> > thread. Change SDHCI to use sdio_signal_irq() to schedule a work item
> > instead. That also requires implementing the ->ack_sdio_irq() mmc host op.
> >
> > Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> > Fixes: c07a48c26519 ("mmc: sdhci: Remove finish_tasklet")
>
> Yes, this fixes the issue for me. You can add my:
>
> Reported-by: Brian Masney <masneyb@...tation.org>
> Tested-by: Brian Masney <masneyb@...tation.org>
>

Applied for fixes, thanks!

Kind regards
Uffe