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From: Jeff Garzik <jgarzik@pobox.com>
To: viro@parcelfarce.linux.theplanet.co.uk
Cc: Linus Torvalds <torvalds@osdl.org>, John Cherry <cherry@osdl.org>,
	Matthew Dharm <mdharm-kernel@one-eyed-alien.net>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
Subject: Re: Linux v2.6.9... (compile stats)
Date: Thu, 21 Oct 2004 04:57:17 -0400	[thread overview]
Message-ID: <417779ED.6040403@pobox.com> (raw)
In-Reply-To: <20041021043557.GK23987@parcelfarce.linux.theplanet.co.uk>

viro@parcelfarce.linux.theplanet.co.uk wrote:
> On Wed, Oct 20, 2004 at 10:37:10PM -0400, Jeff Garzik wrote:
> 
>>viro@parcelfarce.linux.theplanet.co.uk wrote:
>>
>>>IDGI.  Why do you insist on releasing these guys in library code?  Even
>>
>>Because there are two distinct and separate models of port mapping/usage:
>>
>>1) A bunch of separate IO address spaces (PIO).  The "mapping" is 
>>currently done in ata_pci_init_native_mode() and ata_pci_init_legacy_mode()
>>
>>2) One single linear address space (MMIO).  The mapping is done in the 
>>low-level driver.
>>
>>#1 is in the library because the logic is duplicated _precisely_, across 
>>multiple host controllers, according to a hardware specification.
>>
>>Thus, if the mapping is done in the library core, so should the unmapping.
> 
> 
> Not really.  You are making the case for having a helper that would unmap
> for case 1 and having it in the library, just as we do for mapping in that

Sure:  libata is a library, so all functions are helpers.  It's just one 
more helper function.


> case.  What you have is different, though - it's a single function that does
> entire ->remove() for all (AFAICS) SATA drivers.

That's intentional, see below.


> And that's where the problem is - decision on releasing resource should belong
> to the driver; sure, it can and should use library helper, just as it did
> when it was grabbing these resources.




> Note, BTW, that current ata_pci_remove_one() is begging for trouble - for
> one thing, it does iounmap() before we get to ata_scsi_release(), i.e.
> ata_host_remove(), i.e. ->port_stop().   And the first look at the drivers
> that provide ->port_stop() shows that ahci_port_stop() does readl()/writel()
> on the ->mmio_base.  Oops...

Ah the perils of an undocumented API :)  You're misunderstanding 
->port_stop.

That's a bug in ahci:  port_stop should never touch the hardware. 
port_stop is only for releasing per-driver resources like kmalloc or DMA 
memory.

Note...  another thing to keep in mind is that all libata drivers use 
ata_pci_remove_one() because that makes it possible to smooth over the 
differences between 2.4 and 2.6 scsi drivers.

> And that's where the problem is - decision on releasing resource should belong
> to the driver; sure, it can and should use library helper, just as it did
> when it was grabbing these resources.
[...]
> free_irq() also looks fishy, BTW.  How about moving all that group past the
> point where you are done with individual ports and merging it (and any other
> unmapping we might want to do) into a single callback?  Depending on whether
> ->host_stop() is really needed early we might use ->host_stop for that...

I don't see any problems, given what I just wrote above.

Just the annoyance of individually mapping and unmapping 4 or 5 PCI 
BARs, and mixing 4 ranges of ISA legacy ioports for good measure.


Now...  addressing the overall theme of your message...  eventually 
libata wants to move to a strict port_{start,stop}, host_{start,stop} 
mechanism where the driver does more of the heavy lifting [by providing 
hooks that call libata helpers, rather than a helper calling hooks as 
ata_pci_remove_one does now].

But to get there will take _many_ iterations, since two things get in 
the way there:
* 2.4 compat
* the necessity to issue several ATA commands before we can respond to 
-any- SCSI commands

	Jeff

  reply	other threads:[~2004-10-21  8:57 UTC|newest]

Thread overview: 242+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-18 22:45 Linux v2.6.9 Linus Torvalds
2004-10-18 23:27 ` Thomas Zehetbauer
2004-10-19  2:54 ` Eric W. Biederman
2004-10-19 16:55   ` Jesper Juhl
2004-10-19 14:36 ` Linux v2.6.9... (compile stats) John Cherry
2004-10-19 16:18   ` Matthew Dharm
2004-10-19 16:49     ` viro
2004-10-19 21:37     ` John Cherry
2004-10-20 22:11     ` John Cherry
2004-10-20 22:41       ` viro
2004-10-21  0:12         ` Linus Torvalds
2004-10-21  0:29           ` Jeff Garzik
2004-10-21  0:44             ` viro
2004-10-21  1:55             ` viro
2004-10-21  1:59               ` Jeff Garzik
2004-10-21  2:24                 ` viro
2004-10-21  2:37                   ` Jeff Garzik
2004-10-21  4:35                     ` viro
2004-10-21  8:57                       ` Jeff Garzik [this message]
2004-10-20 22:50       ` Dave Jones
2004-10-19 17:38 ` Linux v2.6.9 and GPL Buyout Jeff V. Merkey
2004-10-19 19:13   ` Russell King
2004-10-19 19:04     ` Jeff V. Merkey
2004-10-19 19:24   ` Kurt Wall
2004-10-19 19:12     ` Jeff V. Merkey
2004-10-19 20:01     ` Richard B. Johnson
2004-10-19 20:39       ` Matt Mackall
2004-10-20  0:06         ` Richard B. Johnson
2004-10-20  5:21           ` Matt Mackall
2004-10-19 19:28   ` Andre Hedrick
2004-10-19 19:10     ` Jeff V. Merkey
2004-10-19 19:30   ` Rik van Riel
2004-10-19 19:05     ` Jeff V. Merkey
2004-10-19 20:14       ` Diego Calleja
2004-10-19 19:41         ` Jeff V. Merkey
2004-10-20  8:27           ` Bernd Petrovitsch
2004-10-20  8:45             ` Jens Axboe
2004-10-19 19:47         ` Jeff V. Merkey
2004-10-19 20:05     ` Richard B. Johnson
2004-10-19 19:38       ` Jeff V. Merkey
2004-10-19 20:30         ` Thomas Gleixner
2004-10-19 20:15           ` Jeff V. Merkey
2004-10-22 23:22           ` Tonnerre
2004-10-19 19:45   ` Ross Biro
2004-10-19 19:36     ` Jeff V. Merkey
2004-10-19 19:54   ` David Johnson
2004-10-19 19:55   ` viro
2004-10-19 19:25     ` Jeff V. Merkey
2004-10-19 20:38   ` Dax Kelson
2004-10-19 20:09     ` Jeff V. Merkey
2004-10-19 22:16       ` Jim Nelson
2004-10-19 22:57         ` Bernd Petrovitsch
2004-10-19 22:27       ` Scott Robert Ladd
2004-10-20 19:41         ` Bill Davidsen
2004-10-20  1:15       ` Horst von Brand
2004-10-20  1:16       ` Bastiaan Spandaw
2004-10-20 19:35         ` Bill Davidsen
2004-10-20  3:45       ` Ryan Anderson
2004-10-20  4:18         ` Lee Revell
2004-10-20  4:41           ` Lee Revell
2004-10-20 11:49             ` Richard B. Johnson
2004-10-29 12:12               ` Semaphore assembly-code bug linux-os
2004-10-29 14:46                 ` Linus Torvalds
2004-10-29 15:11                   ` Andi Kleen
2004-10-29 18:18                     ` Linus Torvalds
2004-10-29 18:35                       ` Richard Henderson
2004-10-29 16:06                   ` Andreas Steinmetz
2004-10-29 17:08                     ` linux-os
2004-10-29 18:06                       ` Linus Torvalds
2004-10-29 18:39                         ` linux-os
2004-10-29 19:12                           ` Linus Torvalds
2004-11-01  1:31                             ` linux-os
2004-11-01  5:49                               ` Linus Torvalds
2004-11-01 20:23                               ` dean gaudet
2004-11-01 20:52                                 ` linux-os
2004-11-01 21:23                                   ` dean gaudet
2004-11-01 22:22                                     ` linux-os
2004-11-01 21:40                                   ` Linus Torvalds
2004-11-01 21:46                                     ` Linus Torvalds
2004-11-02 15:02                                       ` linux-os
2004-11-02 16:02                                         ` Linus Torvalds
2004-11-02 16:06                                           ` Linus Torvalds
2004-11-02 16:51                                             ` linux-os
2004-11-01 22:16                                     ` linux-os
2004-11-01 22:26                                       ` Linus Torvalds
2004-11-01 23:14                                         ` linux-os
2004-11-01 23:42                                           ` Linus Torvalds
2004-11-03  1:52                                       ` Horst von Brand
2004-11-03 21:24                                       ` Bill Davidsen
2004-11-02  6:37                                     ` Chris Friesen
2004-10-29 18:58                         ` Andreas Steinmetz
2004-10-29 19:15                           ` Linus Torvalds
2004-10-29 19:40                             ` Andreas Steinmetz
2004-10-29 19:56                               ` Linus Torvalds
2004-10-29 22:07                                 ` Jeff Garzik
2004-10-29 23:50                               ` dean gaudet
2004-10-30  0:15                                 ` Linus Torvalds
2004-10-29 23:37                         ` dean gaudet
2004-10-29 17:22                   ` linux-os
2004-10-29 17:55                     ` Richard Henderson
2004-10-29 18:17                       ` linux-os
2004-10-29 18:42                         ` Linus Torvalds
2004-10-29 18:54                           ` Linus Torvalds
2004-10-30  3:35                           ` Jeff Garzik
2004-10-29 19:20                     ` Linus Torvalds
2004-10-29 19:26                       ` Linus Torvalds
2004-10-29 21:03                       ` Linus Torvalds
2004-10-29 17:57                   ` Richard Henderson
2004-10-29 18:37                   ` Gabriel Paubert
2004-10-20  5:58           ` Linux v2.6.9 and GPL Buyout John Alvord
2004-10-20 14:42           ` Martin Waitz
2004-10-21 23:59       ` Kelledin
2004-10-22  8:46       ` Bernd Petrovitsch
2004-10-22  9:07       ` David Weinehall
2004-10-22 16:15         ` Jeff V. Merkey
2004-10-22 17:52           ` Al Viro
2004-10-22 17:22             ` Jeff V. Merkey
2004-10-22 19:37               ` Jeff V. Merkey
2004-10-22 20:46                 ` Grahame White
2004-10-22 20:58                 ` Buddy Lucas
2004-10-22 21:00                 ` Richard B. Johnson
2004-10-22 21:03                 ` Thomas Gleixner
2004-10-23 12:33                 ` Bernd Petrovitsch
2004-10-24 14:15                 ` Kai Henningsen
2004-10-27  1:45                 ` Horst von Brand
2004-10-24 11:00           ` Matthias Andree
2004-10-24 14:13           ` Kai Henningsen
2004-10-25 18:44             ` Bill Davidsen
2004-10-20 19:46     ` Bill Davidsen
2004-10-19 21:02   ` Pekka Pietikainen
2004-10-19 20:27     ` Jeff V. Merkey
2004-10-22  6:54       ` Erik Andersen
2004-10-22 16:12         ` Jeff V. Merkey
2004-10-19 21:17     ` Paul Fulghum
2004-10-20 20:41     ` Geert Uytterhoeven
2004-10-23 13:43       ` James Bruce
2004-10-19 21:26   ` Ramón Rey Vicente
2004-10-19 22:52   ` Buddy Lucas
2004-10-20 23:43   ` Eric Bambach
2004-10-20 23:48     ` Eric Bambach
2004-10-20 23:59     ` Hua Zhong
2004-10-21  0:13     ` Russell Miller
2004-10-21  0:18       ` Adam Heath
2004-10-21 10:16       ` Horst von Brand
2004-10-22  8:48   ` Ingo Molnar
2004-10-22 16:15     ` Jeff V. Merkey
2004-10-23  0:14   ` Jon Masters
2004-10-22 23:46     ` Jeff V. Merkey
2004-10-23  0:57       ` Jon Masters
2004-10-23  4:42         ` Jeff V. Merkey
2004-10-23  6:32           ` Nick Piggin
     [not found]             ` <20041023064538.GA7866@galt.devicelogics.com>
2004-10-23  7:20               ` Jeff V. Merkey
2004-10-23 10:11           ` Gene Heskett
2004-10-23 16:28           ` Linus Torvalds
2004-10-24  2:48             ` Jesper Juhl
2004-10-24  5:11             ` Jeff V. Merkey
2004-10-24 11:14               ` Jon Masters
2004-10-24 11:50               ` Jim Nelson
2004-10-24 15:35               ` Ingo Molnar
2004-10-24 15:53               ` Bernd Petrovitsch
2004-10-31 23:14               ` Jan 'JaSan' Sarenik
2004-10-24  2:11           ` Buddy Lucas
2004-10-23  0:38     ` Lee Revell
2004-10-23  0:07       ` Jeff V. Merkey
2004-10-23  1:06         ` Lee Revell
2004-10-21  2:41 ` Linux v2.6.9 (Strange tty problem?) Paul
2004-10-21  9:07   ` Alan Cox
2004-10-21 12:39     ` Russell King
2004-10-21 13:20     ` Paul Fulghum
2004-10-21 15:37       ` Alan Cox
2004-10-21 17:00         ` Paul Fulghum
2004-10-21 15:47       ` Paul Fulghum
2004-10-21 18:12     ` Paul Fulghum
2004-10-31 21:11 ` Linux v2.6.9 dies when starting X on radeon 9200 SE PCI Helge Hafting
2004-11-04 16:01 Linux-2.6.9 won't allow a write to a NTFS file-system linux-os
2004-11-04 16:48 ` Giuseppe Bilotta
2004-11-04 17:09   ` linux-os
2004-11-04 17:40     ` Giuseppe Bilotta
2004-11-04 17:46     ` Mathieu Segaud
2004-11-04 22:17     ` Anton Altaparmakov
2004-11-04 22:18       ` Anton Altaparmakov
2004-11-04 22:38       ` linux-os
2004-11-05 14:43         ` Rahul Karnik
2004-11-05  1:46     ` Horst von Brand
2004-11-05 12:41       ` linux-os
2004-12-02  0:04 What if? Imanpreet Singh Arora
2004-12-02  4:40 ` Theodore Ts'o
2004-12-02  6:39   ` Norbert van Nobelen
2004-12-02  8:24   ` James Bruce
2004-12-02 20:25     ` Theodore Ts'o
2004-12-03  2:23       ` David Schwartz
2004-12-02  8:33   ` J.A. Magallon
2004-12-02 10:46     ` Bernd Petrovitsch
2004-12-02 10:56       ` Pawel Sikora
2004-12-13 15:23       ` H. Peter Anvin
2004-12-13 21:08         ` J.A. Magallon
2004-12-16  0:57           ` Alan Cox
2004-12-16  2:44             ` H. Peter Anvin
2004-12-16 13:23               ` Alan Cox
2004-12-16 15:23                 ` Geert Uytterhoeven
2004-12-16 20:37                 ` H. Peter Anvin
2004-12-16 20:52                   ` Jan Engelhardt
2004-12-16 20:56                     ` H. Peter Anvin
2004-12-16 21:08                       ` Jan Engelhardt
2004-12-02 10:25 ` Jan Engelhardt
2004-12-05  0:23   ` Horst von Brand
2004-12-05  6:21     ` Kyle Moffett
2004-12-05 22:43       ` Horst von Brand
2004-12-06 17:27         ` linux-os
2004-12-06 18:52           ` Horst von Brand
2004-12-02 10:53 ` Bernd Petrovitsch
2004-12-11  8:52 ` Gábor Lénárt
2004-12-17  1:33 [Coverity] Untrusted user data in kernel Bryan Fulton
2004-12-17  5:15 ` James Morris
2004-12-17  5:15   ` James Morris
2004-12-17  5:25   ` Patrick McHardy
2004-12-17  6:45     ` James Morris
2004-12-17  6:45       ` James Morris
2004-12-17 13:18       ` Tomas Carnecky
2004-12-17 19:16         ` David S. Miller
2004-12-17 19:16           ` David S. Miller
2004-12-17 19:34           ` Tomas Carnecky
2004-12-17 19:30             ` David S. Miller
2004-12-17 19:30               ` David S. Miller
2004-12-17 15:47       ` Bill Davidsen
2004-12-17 16:11         ` linux-os
2004-12-17 16:31           ` Oliver Neukum
2004-12-17 18:37           ` Bill Davidsen
2004-12-17 19:18           ` Tomas Carnecky
2004-12-17 19:30             ` Oliver Neukum
2004-12-17 19:39               ` Tomas Carnecky
2004-12-18  1:42           ` Horst von Brand
2004-12-17 15:10   ` Pavel Machek
2004-12-17 15:38     ` James Morris
2005-01-05 12:04 ` Marcelo Tosatti
2005-01-05 15:09   ` Jan Harkes
2005-01-05 23:17   ` Nathan Scott
     [not found]   ` <20050105161653.GF13455@fi.muni.cz>
     [not found]     ` <20050105140549.GA14622@logos.cnet>
2005-01-06  9:18       ` Jan Kasprzak
2005-01-06 14:48         ` Paulo Marques
2005-01-06 16:29         ` Alan Cox
2005-01-07 21:49   ` [PATCH 2.4.29-pre3-bk4] fs/coda " Jan Harkes
2005-01-07 21:54   ` [PATCH 2.6.10-mm2] " Jan Harkes

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