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Message-Id: <201205302341.21821.rjw@sisk.pl>
Date: Wed, 30 May 2012 23:41:21 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Dan Williams <dan.j.williams@...el.com>
Cc: linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
Len Brown <len.brown@...el.com>, mroos@...ux.ee,
Arjan van de Ven <arjan@...ux.intel.com>,
James Bottomley <JBottomley@...allels.com>
Subject: Re: [PATCH v2 4/4] scsi: cleanup usages of scsi_complete_async_scans
On Wednesday, May 30, 2012, Rafael J. Wysocki wrote:
> On Wednesday, May 30, 2012, Dan Williams wrote:
> > Now that scsi registers its async scan work with the async subsystem,
> > wait_for_device_probe() is sufficient for ensuring all scanning is
> > complete.
> >
> > Cc: Arjan van de Ven <arjan@...ux.intel.com>
> > Cc: Len Brown <len.brown@...el.com>
> > Cc: Rafael J. Wysocki <rjw@...k.pl>
> > Cc: James Bottomley <JBottomley@...allels.com>
> > Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> > ---
> > drivers/scsi/scsi_scan.c | 12 ------------
> > drivers/scsi/scsi_wait_scan.c | 15 +++++----------
> > include/scsi/scsi_scan.h | 11 -----------
> > kernel/power/hibernate.c | 8 --------
> > kernel/power/user.c | 2 --
> > 5 files changed, 5 insertions(+), 43 deletions(-)
> > delete mode 100644 include/scsi/scsi_scan.h
> >
> > diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> > index fb42aa0..20c7108 100644
> > --- a/drivers/scsi/scsi_scan.c
> > +++ b/drivers/scsi/scsi_scan.c
> > @@ -184,18 +184,6 @@ int scsi_complete_async_scans(void)
> > return 0;
> > }
> >
> > -/* Only exported for the benefit of scsi_wait_scan */
> > -EXPORT_SYMBOL_GPL(scsi_complete_async_scans);
> > -
> > -#ifndef MODULE
> > -/*
> > - * For async scanning we need to wait for all the scans to complete before
> > - * trying to mount the root fs. Otherwise non-modular drivers may not be ready
> > - * yet.
> > - */
> > -late_initcall(scsi_complete_async_scans);
> > -#endif
> > -
> > /**
> > * scsi_unlock_floptical - unlock device via a special MODE SENSE command
> > * @sdev: scsi device to send command to
> > diff --git a/drivers/scsi/scsi_wait_scan.c b/drivers/scsi/scsi_wait_scan.c
> > index 74708fc..57de24a 100644
> > --- a/drivers/scsi/scsi_wait_scan.c
> > +++ b/drivers/scsi/scsi_wait_scan.c
> > @@ -12,21 +12,16 @@
> >
> > #include <linux/module.h>
> > #include <linux/device.h>
> > -#include <scsi/scsi_scan.h>
> >
> > static int __init wait_scan_init(void)
> > {
> > /*
> > - * First we need to wait for device probing to finish;
> > - * the drivers we just loaded might just still be probing
> > - * and might not yet have reached the scsi async scanning
> > + * This will not return until all async work (system wide) is
> > + * quiesced. Probing queues host-scanning work to the async
> > + * queue which is why we don't need a separate call to
> > + * scsi_complete_async_scans()
> > */
> > wait_for_device_probe();
> > - /*
> > - * and then we wait for the actual asynchronous scsi scan
> > - * to finish.
> > - */
> > - scsi_complete_async_scans();
> > return 0;
> > }
> >
> > @@ -38,5 +33,5 @@ MODULE_DESCRIPTION("SCSI wait for scans");
> > MODULE_AUTHOR("James Bottomley");
> > MODULE_LICENSE("GPL");
> >
> > -late_initcall(wait_scan_init);
> > +module_init(wait_scan_init);
> > module_exit(wait_scan_exit);
> > diff --git a/include/scsi/scsi_scan.h b/include/scsi/scsi_scan.h
> > deleted file mode 100644
> > index 7889888..0000000
> > --- a/include/scsi/scsi_scan.h
> > +++ /dev/null
> > @@ -1,11 +0,0 @@
> > -#ifndef _SCSI_SCSI_SCAN_H
> > -#define _SCSI_SCSI_SCAN_H
> > -
> > -#ifdef CONFIG_SCSI
> > -/* drivers/scsi/scsi_scan.c */
> > -extern int scsi_complete_async_scans(void);
> > -#else
> > -static inline int scsi_complete_async_scans(void) { return 0; }
> > -#endif
> > -
> > -#endif /* _SCSI_SCSI_SCAN_H */
> > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> > index e09dfbf..821114a 100644
> > --- a/kernel/power/hibernate.c
> > +++ b/kernel/power/hibernate.c
> > @@ -25,7 +25,6 @@
> > #include <linux/freezer.h>
> > #include <linux/gfp.h>
> > #include <linux/syscore_ops.h>
> > -#include <scsi/scsi_scan.h>
> >
> > #include "power.h"
> >
> > @@ -735,13 +734,6 @@ static int software_resume(void)
> > async_synchronize_full();
> > }
> >
> > - /*
> > - * We can't depend on SCSI devices being available after loading
> > - * one of their modules until scsi_complete_async_scans() is
> > - * called and the resume device usually is a SCSI one.
> > - */
> > - scsi_complete_async_scans();
> > -
>
> I believe this is wrong. You're going to introduce a regression on systems
> using built-in hibernation and built-in SCSI stack.
Ah, wait. Do I understand correctly that wait_for_device_probe()
is now going to do an equivalent of scsi_complete_async_scans()?
If so, that should work, in which case please disregard my previous
messages in this thread.
Thanks,
Rafael
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