linux-kernel - RE: mmc: sdhci-pci: why no .shutdown() implemented

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Date:	Mon, 12 Mar 2012 14:30:24 +0000
From:	"Mansoor, Illyas" <illyas.mansoor@...el.com>
To:	"linux-pm@...ts.linux-foundation.org" 
	<linux-pm@...ts.linux-foundation.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Hunter, Adrian" <adrian.hunter@...el.com>
Subject: RE: mmc: sdhci-pci: why no .shutdown() implemented

> > On our platform we implemented a BUG in pci_set_power_state callback
> > when the shutdown Is in progress, and we caught sdhci-pci doing
> > pci_set_power_state(D0) when shutdown was Already in progress.
> >
> > My question, why doesn't sdhci-pci.c implement a .shutdown() callback
> > and close the device After doing sys_sync()?
> >
> > Is there some reason behind it not doing a graceful shutdown.
> 
> In general, the kernel does not know how to do a graceful shutdown.  There may
> be any number of housekeeping activities that userspace wishes to do before
> shutting down.

I see some storage drivers do implement .shutdown() callbacks do you think
sdhci-pci
could also do the same?

immansoo@...ansoo-desktop:~/Linux_kernel/linux-stable/drivers/mmc$ find . -name
\*.c -exec grep \.shutdown -H {} \;
./host/s3cmci.c:static void s3cmci_shutdown(struct platform_device *pdev)
./host/s3cmci.c:        s3cmci_shutdown(pdev);
./host/s3cmci.c:        .shutdown       = s3cmci_shutdown,

> 
> If file systems are not getting sync'd that is a userspace problem, not a
kernel
> problem.

I agree the issue needs to be fixed in user-space, so it does not request
Storage device during shutdown. 

Shouldn't we also make sure we don't open a device during shutdown, that way we
make
sure at least we don't stay in device power'd up state during power-off.

It's not that the file system is not getting sync'd, but issue is bringing  up
the device
during shutdown, because once the shutdown starts there is no way to stop it
and the device may be left in undefined state.


> 
> >
> > I think it could cause corruption, since there is no guarantee when
> > the system will power-off/reboot/halt
> >
> > I just implemented a patch to fix this, if it's a good fix I'll submit.
> >
> > diff --git a/drivers/mmc/host/sdhci-pci.c
> > b/drivers/mmc/host/sdhci-pci.c index f5fe05c..e0818c9 100644
> > --- a/drivers/mmc/host/sdhci-pci.c
> > +++ b/drivers/mmc/host/sdhci-pci.c
> > @@ -23,6 +23,7 @@
> >  #include <linux/regulator/consumer.h>  #include <linux/pm_runtime.h>
> > #include <linux/async.h>
> > +#include <linux/syscalls.h>
> >
> >  #include <asm/scatterlist.h>
> >  #include <asm/io.h>
> > @@ -1342,6 +1343,34 @@ err:
> >         return ret;
> >  }
> >
> > +static void sdhci_pci_shutdown(struct pci_dev *pdev) {
> > +       int i;
> > +       struct sdhci_pci_chip *chip;
> > +
> > +       printk(KERN_INFO "%s: Syncing filesystems ... ", __func__);
> > +       sys_sync();
> > +       printk("done.\n");
> > +
> > +       pm_runtime_get_sync(&pdev->dev);
> > +
> > +       chip = pci_get_drvdata(pdev);
> > +
> > +       if (chip) {
> > +               for (i = 0;i < chip->num_slots; i++)
> > +                       sdhci_pci_remove_slot(chip->slots[i]);
> > +
> > +               pci_set_drvdata(pdev, NULL);
> > +               kfree(chip);
> > +       }
> > +
> > +       pci_disable_device(pdev);
> > +
> > +       pm_runtime_put_noidle(&pdev->dev);
> > +       pm_runtime_forbid(&pdev->dev);
> > +       pm_runtime_disable(&pdev->dev); }
> > +
> >  static void __devexit sdhci_pci_remove(struct pci_dev *pdev)  {
> >         int i;
> > @@ -1473,6 +1502,7 @@ static struct pci_driver sdhci_driver = {
> >         .id_table =     pci_ids,
> >         .probe =        sdhci_pci_probe,
> >         .remove =       __devexit_p(sdhci_pci_remove),
> > +       .shutdown =     sdhci_pci_shutdown,
> >
> >
> > -Illyas


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