linux-kernel - [PATCH v2 0/2] Avoid system abort by moving pm domain's detach after devres_release

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Date:   Tue, 15 Aug 2017 16:36:55 +0800
From:   Shawn Lin <shawn.lin@...k-chips.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        Jaehoon Chung <jh80.chung@...sung.com>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shawn Lin <shawn.lin@...k-chips.com>
Subject: [PATCH v2 0/2] Avoid system abort by moving pm domain's detach after devres_release_all

CONFIG_DEBUG_SHIRQ will fire extra irq action to call the registered
irq callback after driver is removed or failed to probe. In general,
the irq callback provided by driver should read its internal registers
to see who fires the irq. So this leads a situation that we access the
registers with a powered-off pm domain that the system abort. This is
a system-wide issue may break lots of drivers, IMHO.

dwmmc driver is one of them suffered from this as it allows the variant
drivers to register shared irq. Please see the commit message of patch 2
for how that happened.

I haven't find a proper way to freeze the genpd_power_off_work_fn
and fire it again when finish devres_release_all indeed. And it
seems to me that device's pm domain detach is always called when
failing to probe or removing the driver. So from a top view, I have to cook
patch 1 for a RFC to see if folks think this's the best way to fix that,
otherwise we may need to fix it everywhere for other drivers.

These patchset was tested by hacking the driver to return a failure for probe
and also by unbinding the driver and all seem to work fine.

Changes in v2:
- include a driver core change to fix the genpd issue.

Shawn Lin (2):
  driver core: detach device's pm_domain after devres_release_all
  mmc: dw_mmc: fix potential system abort if activating
    CONFIG_DEBUG_SHIRQ

 drivers/base/dd.c         | 35 +++++++++++++++++++++++++++++-----
 drivers/base/platform.c   | 18 ++----------------
 drivers/mmc/host/dw_mmc.c | 48 +++++++++++++++++++++++------------------------
 3 files changed, 55 insertions(+), 46 deletions(-)

-- 
1.9.1