Re: Issue with Broadcom wireless in 5.2rc1 (was Re: [PATCH] mmc: sdhci: queue work after sdhci_defer_done())

From: Brian Masney <masneyb@onstation.org>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arend Van Spriel <arend.vanspriel@broadcom.com>,
	Franky Lin <franky.lin@broadcom.com>,
	Hante Meuleman <hante.meuleman@broadcom.com>,
	Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
	Wright Feng <wright.feng@cypress.com>,
	ulf.hansson@linaro.org, faiz_abbas@ti.com,
	linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, Kalle Valo <kvalo@codeaurora.org>,
	linux-wireless@vger.kernel.org,
	brcm80211-dev-list.pdl@broadcom.com,
	brcm80211-dev-list@cypress.com, netdev@vger.kernel.org
Subject: Re: Issue with Broadcom wireless in 5.2rc1 (was Re: [PATCH] mmc: sdhci: queue work after sdhci_defer_done())
Date: Mon, 27 May 2019 08:50:26 -0400	[thread overview]
Message-ID: <20190527125026.GA4272@basecamp> (raw)
In-Reply-To: <ead7f268-b730-3541-31f7-4499556efec0@intel.com>

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@intel.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@intel.com>
> Fixes: c07a48c26519 ("mmc: sdhci: Remove finish_tasklet")

Yes, this fixes the issue for me. You can add my:

Reported-by: Brian Masney <masneyb@onstation.org>
Tested-by: Brian Masney <masneyb@onstation.org>

Thanks,

Brian