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* Re: bug in /net/core/dev.c
@ 2001-06-13 10:03 DJBARROW
  2001-06-13 10:18 ` David S. Miller
  0 siblings, 1 reply; 16+ messages in thread
From: DJBARROW @ 2001-06-13 10:03 UTC (permalink / raw)
  To: alan, David S. Miller; +Cc: linux-kernel



Hi,

Here is the patch again for the benefit of those who are allergic to
opening enclosures.
I believe it will only take about 30 seconds of "real thinking" for those
familiar with dev.c to make
an evaluation of the patch.

Those already familiar with the bug can skip this paragraph,
The bug fixes a problem that occurs if register_netdev gets called before
net_dev_init the dev->refcnt gets incremented to 2 after net_dev_init is
called
& unregister_netdev will loop forever.


The  following additional lines at the top of register_netdev will call
net_dev_init
if it hasn't already been called & by doing this I'm able to remove about
20 lines of special
case code in this function.
+    if (dev_boot_phase)
+         net_dev_init();

The following additional lines in net_dev_init will do a quick exit if this
routine
as already been called ( as may be done from register_netdev ).
+    if(!dev_boot_phase)
+         return 0;





--- net/core/dev.old.c   Wed May 30 14:24:47 2001
+++ net/core/dev.c  Tue Jun 12 15:37:58 2001
@@ -20,6 +20,10 @@
  *              Pekka Riikonen <priikone@poesidon.pspt.fi>
  *
  *  Changes:
+ *              D.J. Barrow     :       Fixed bug where dev->refcnt gets
set to 2
+ *                                      if register_netdev gets called
before
+ *                                      net_dev_init & also removed a few
lines
+ *                                      of code in the process.
  *       Alan Cox  :    device private ioctl copies fields back.
  *       Alan Cox  :    Transmit queue code does relevant stunts to
  *                      keep the queue safe.
@@ -2382,6 +2386,7 @@
  *  will not get the same name.
  */

+int net_dev_init(void);
 int register_netdevice(struct net_device *dev)
 {
     struct net_device *d, **dp;
@@ -2396,48 +2401,8 @@
     dev->fastpath_lock=RW_LOCK_UNLOCKED;
 #endif

-    if (dev_boot_phase) {
-#ifdef CONFIG_NET_DIVERT
-         ret = alloc_divert_blk(dev);
-         if (ret)
-              return ret;
-#endif /* CONFIG_NET_DIVERT */
-
-         /* This is NOT bug, but I am not sure, that all the
-            devices, initialized before netdev module is started
-            are sane.
-
-            Now they are chained to device boot list
-            and probed later. If a module is initialized
-            before netdev, but assumes that dev->init
-            is really called by register_netdev(), it will fail.
-
-            So that this message should be printed for a while.
-          */
-         printk(KERN_INFO "early initialization of device %s is
deferred\n", dev->name);
-
-         /* Check for existence, and append to tail of chain */
-         for (dp=&dev_base; (d=*dp) != NULL; dp=&d->next) {
-              if (d == dev || strcmp(d->name, dev->name) == 0) {
-                   return -EEXIST;
-              }
-         }
-         dev->next = NULL;
-         write_lock_bh(&dev_base_lock);
-         *dp = dev;
-         dev_hold(dev);
-         write_unlock_bh(&dev_base_lock);
-
-         /*
-          *   Default initial state at registry is that the
-          *   device is present.
-          */
-
-         set_bit(__LINK_STATE_PRESENT, &dev->state);
-
-         return 0;
-    }
-
+    if (dev_boot_phase)
+         net_dev_init();
 #ifdef CONFIG_NET_DIVERT
     ret = alloc_divert_blk(dev);
     if (ret)
@@ -2679,7 +2644,9 @@
 {
     struct net_device *dev, **dp;
     int i;
-
+
+    if(!dev_boot_phase)
+         return 0;
 #ifdef CONFIG_NET_SCHED
     pktsched_init();
 #endif


D.J. Barrow Gnu/Linux for S/390 kernel developer
eMail: djbarrow@de.ibm.com,barrow_dj@yahoo.com
Phone: +49-(0)7031-16-2583
IBM Germany Lab, Schönaicherstr. 220, 71032 Böblingen



^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-13 10:03 bug in /net/core/dev.c DJBARROW
@ 2001-06-13 10:18 ` David S. Miller
  0 siblings, 0 replies; 16+ messages in thread
From: David S. Miller @ 2001-06-13 10:18 UTC (permalink / raw)
  To: DJBARROW; +Cc: alan, linux-kernel


DJBARROW@de.ibm.com writes:
 > Here is the patch again for the benefit of those who are allergic to
 > opening enclosures.

Yes, this one is for those who are not allergic to line-breaks messing
up the patch, it seems :-)

The only reservation I had was wrt. procfs, but it dawned on me that
we init procfs explicitly in init/main.c before initcalls are made.

So I've fixed up the line breaks and coding style issues, and applied
your patch.  Thanks.

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 18:38 DJBARROW
@ 2001-06-12 18:44 ` David S. Miller
  0 siblings, 0 replies; 16+ messages in thread
From: David S. Miller @ 2001-06-12 18:44 UTC (permalink / raw)
  To: DJBARROW; +Cc: Keith Owens, schwidefsky, Ulrich.Weigand, linux-kernel


DJBARROW@de.ibm.com writes:
 > Why not ?,
 > the patch is less than 15 lines & you've managed to send me & others about
 > 10 emails
 > expressing a formed opinion without even looking at the code.

Because those 10 mails were passive replies, reading the patch
requires real thinking.

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
@ 2001-06-12 18:38 DJBARROW
  2001-06-12 18:44 ` David S. Miller
  0 siblings, 1 reply; 16+ messages in thread
From: DJBARROW @ 2001-06-12 18:38 UTC (permalink / raw)
  To: David S. Miller, Keith Owens, schwidefsky, Ulrich.Weigand; +Cc: linux-kernel

[-- Attachment #1: Type: text/plain, Size: 608 bytes --]




Why not ?,
the patch is less than 15 lines & you've managed to send me & others about
10 emails
expressing a formed opinion without even looking at the code.

D.J. Barrow Gnu/Linux for S/390 kernel developer
eMail: djbarrow@de.ibm.com,barrow_dj@yahoo.com
Phone: +49-(0)7031-16-2583
IBM Germany Lab, Schönaicherstr. 220, 71032 Böblingen


"David S. Miller" <davem@redhat.com> on 12.06.2001 20:28:46

Please respond to "David S. Miller" <davem@redhat.com>

To:   Denis Joseph Barrow/Germany/Contr/IBM@IBMDE
cc:   Keith Owens <kaos@ocs.com.au>
Subject:  Re: bug in /net/core/dev.c




[-- Attachment #2: Type: text/plain, Size: 394 bytes --]



DJBARROW@de.ibm.com writes:
 > I'm sure you both understand the problem & have a valid solution.
 > But out of curiousity have either of you looked at the
dev.c.2.4.5.v2.patch
 > & have an opinon on it.

Not yet, I simply don't have the time today.  I'll look at it tomorrow
or the next day.

Besides, debugging PCI x86 bios code is so much fun. :-(

Later,
David S. Miller
davem@redhat.com


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 17:05 Ulrich.Weigand
@ 2001-06-12 17:20 ` Keith Owens
  0 siblings, 0 replies; 16+ messages in thread
From: Keith Owens @ 2001-06-12 17:20 UTC (permalink / raw)
  To: Ulrich.Weigand; +Cc: David S. Miller, DJBARROW, alan, linux-kernel

On Tue, 12 Jun 2001 19:05:01 +0200, 
Ulrich.Weigand@de.ibm.com wrote:
>Keith, it's probably much easier to just change arch/s390/Makefile
>to link the S/390 drivers *after* all common drivers by moving
>drivers/s390/io.o to $DRIVERS instead of $CORE_FILES.

That should work, although it would be yet another (and different) way
of doing things.  Your method would not work for SCSI drivers, they
have to go in the middle of drivers/scsi/Makefile.

That last point is only relevant if s390 supports native SCSI.  SCSI
disks emulating 33[89]0 does not count, the cpu does not issue SCSI
commands.  Are there any native SCSI devices for s390 or do they all
emulate IBM devices?  I can just see somebody trying to fit SCSI
commands into a CCW and IOB :).


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
@ 2001-06-12 17:05 Ulrich.Weigand
  2001-06-12 17:20 ` Keith Owens
  0 siblings, 1 reply; 16+ messages in thread
From: Ulrich.Weigand @ 2001-06-12 17:05 UTC (permalink / raw)
  To: Keith Owens; +Cc: David S. Miller, DJBARROW, alan, linux-kernel



Keith Owens wrote:

>Minimal (and totally untested) patch to compile s390/net as part of the
>other network drivers follows - if it's good enough for acorn, it's
>good enough for s390.  The method is as ugly as hell but it is the
>least possible change for 2.4, major redesign will have to wait for
>2.5.  Patch against 2.4.6-pre2.

Keith, it's probably much easier to just change arch/s390/Makefile
to link the S/390 drivers *after* all common drivers by moving
drivers/s390/io.o to $DRIVERS instead of $CORE_FILES.

This should fix this particular problem, and appears to be more
logical anyway.

We are just testing this change whether any other problem crop up;
if it's OK we'll send a patch ...



Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

--
  Dr. Ulrich Weigand
  Linux for S/390 Design & Development
  IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
  Phone: +49-7031/16-3727   ---   Email: Ulrich.Weigand@de.ibm.com



^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 16:43 DJBARROW
  2001-06-12 16:51 ` David S. Miller
@ 2001-06-12 17:02 ` Keith Owens
  1 sibling, 0 replies; 16+ messages in thread
From: Keith Owens @ 2001-06-12 17:02 UTC (permalink / raw)
  To: DJBARROW; +Cc: schwidefsky, Ulrich.Weigand, linux-kernel

On Tue, 12 Jun 2001 18:43:41 +0200, 
DJBARROW@de.ibm.com wrote:
>Hi Keith,
>This is a cure the syntom not the problem, build order shouldn't mess up
>something this simple.

I totally agree on one point.  Having the automatic initialisers in the
same source as the related code is a good idea, it is far better than
the old Space.c method.  Automatically executing the initialisers in
the order they are linked into vmlinux is also a good idea, you must
have some automatic order or you are back to the horrors of Space.c.
But controlling the link order of the initialisers as a side effect of
Makefile compile order sucks big rocks, especially when you have some
Makefiles executing other Makefiles which are not their children.

Link order should be independent of Makefile compile order and it
should be explicitly specified, instead of occurring as a little known
side effect of the convoluted and twisted way that the Makefile tree is
processed.  Alas Linus likes it this way :(.  At least with my 2.5
Makefile rewrite[*] it is more obvious what is going on.  I abhore the
line order dependencies and controling link order at the level of
entire directories when it should be at the level of individual
sources.

>I've forwarded your patch to Ulrich & Martin ( the s390 maintainers ) &
>they may use it
>seeing as you & possibly others would prefer a /drivers/net/s390.

DaveM suggested a drivers/net/s390, I recommended against changing the
diretory structure right now, wait for 2.5.  My patch just changes the
compilation order for drivers/s390/net while keeping the same name.


[*] Extract from top level Makefile in my 2.5 rewrite.

# Link order information to build vmlinux.

link_subdirs(arch/$(ARCH)/boot)
link_subdirs(init)

link_subdirs($(arch_core_subdirs))

link_subdirs(kernel)
link_subdirs(mm)
link_subdirs(fs)
link_subdirs(ipc)

# FIXME: Built from the DRIVERS definitions in the old Makefile.  Some of this
# is just to link intermediate objects into the kernel, some of it is link order
# specific but the old Makefile had no documentation.  Preserve the old list,
# even though most of it is unnecessary.  The problem is, we do not know which
# bits are necessary because they have link order requirements.  Anybody feeling
# brave?  KAO

link_subdirs(drivers/block)
link_subdirs(drivers/char)
link_subdirs(drivers/misc)
link_subdirs(drivers/net)
link_subdirs(drivers/media)
...
link_subdirs(drivers/acpi)
link_subdirs(drivers/md)

link_subdirs($(arch_drivers_subdirs))

link_subdirs(net)

link_subdirs($(arch_libs))
link_subdirs(lib)


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 16:43 DJBARROW
@ 2001-06-12 16:51 ` David S. Miller
  2001-06-12 17:02 ` Keith Owens
  1 sibling, 0 replies; 16+ messages in thread
From: David S. Miller @ 2001-06-12 16:51 UTC (permalink / raw)
  To: DJBARROW; +Cc: Keith Owens, schwidefsky, Ulrich.Weigand, linux-kernel


DJBARROW@de.ibm.com writes:
 > This is a cure the syntom not the problem, build order shouldn't mess up
 > something this simple.

The refcounting issue you've described is a bug, and so is
initializing a network device before net_dev_init() has been invoked.
These two things are equally buggy.

Build order does mess up things this simple, look at the comments at
the top of drivers/scsi/Makefile if you don't believe me :-)

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
@ 2001-06-12 16:43 DJBARROW
  2001-06-12 16:51 ` David S. Miller
  2001-06-12 17:02 ` Keith Owens
  0 siblings, 2 replies; 16+ messages in thread
From: DJBARROW @ 2001-06-12 16:43 UTC (permalink / raw)
  To: Keith Owens, schwidefsky, Ulrich.Weigand; +Cc: linux-kernel

[-- Attachment #1: Type: text/plain, Size: 908 bytes --]




Hi Keith,
This is a cure the syntom not the problem, build order shouldn't mess up
something this simple.
I've forwarded your patch to Ulrich & Martin ( the s390 maintainers ) &
they may use it
seeing as you & possibly others would prefer a /drivers/net/s390.
David admitted it is a bug, if the patch is good hopefully it will be
taken,
 it if better can be done hopefully someone will do better.

D.J. Barrow Gnu/Linux for S/390 kernel developer
eMail: djbarrow@de.ibm.com,barrow_dj@yahoo.com
Phone: +49-(0)7031-16-2583
IBM Germany Lab, Schönaicherstr. 220, 71032 Böblingen


Keith Owens <kaos@ocs.com.au> on 12.06.2001 18:11:26

Please respond to Keith Owens <kaos@ocs.com.au>

To:   "David S. Miller" <davem@redhat.com>
cc:   Denis Joseph Barrow/Germany/Contr/IBM@IBMDE,
      alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org
Subject:  Re: bug in /net/core/dev.c




[-- Attachment #2: Type: text/plain, Size: 2000 bytes --]


On Tue, 12 Jun 2001 08:46:00 -0700 (PDT),
"David S. Miller" <davem@redhat.com> wrote:
>So, if the s390 folks move their stuff into the appropriate spot it
>will work.  In fact, I personally like to see the s390 net devices
>under drivers/net/s390 anyways.  They'll get free maintenance from
>myself and Jeff Garzik in this way as I rarely look int
>drivers/${PLATFORM} type directories unless I'm doing a tree-wide
>grep. :-)

Leave s390 separate for the moment, all the other architectures work
the same way.

Minimal (and totally untested) patch to compile s390/net as part of the
other network drivers follows - if it's good enough for acorn, it's
good enough for s390.  The method is as ugly as hell but it is the
least possible change for 2.4, major redesign will have to wait for
2.5.  Patch against 2.4.6-pre2.

Index: 6-pre2.1/drivers/s390/Makefile
--- 6-pre2.1/drivers/s390/Makefile Fri, 13 Apr 2001 12:02:38 +1000 kaos
(linux-2.4/u/b/43_Makefile 1.3 644)
+++ 6-pre2.1(w)/drivers/s390/Makefile Wed, 13 Jun 2001 02:05:24 +1000 kaos
(linux-2.4/u/b/43_Makefile 1.3 644)
@@ -4,7 +4,7 @@

 O_TARGET := io.o

-subdir-y := block char misc net
+subdir-y := block char misc
 subdir-m := $(subdir-y)
 obj-y := $(foreach dir,$(subdir-y),$(dir)/s390-$(dir).o)

@@ -12,3 +12,5 @@ obj-y += s390io.o s390mach.o s390dyn.o i
 export-objs += ccwcache.o idals.o s390dyn.o s390io.o

 include $(TOPDIR)/Rules.make
+
+# the NET subdir is included from drivers/net now
Index: 6-pre2.1/drivers/net/Makefile
--- 6-pre2.1/drivers/net/Makefile Thu, 17 May 2001 10:25:35 +1000 kaos
(linux-2.4/l/c/26_Makefile 1.1.1.1.3.3.1.1.1.2 644)
+++ 6-pre2.1(w)/drivers/net/Makefile Wed, 13 Jun 2001 02:03:09 +1000 kaos
(linux-2.4/l/c/26_Makefile 1.1.1.1.3.3.1.1.1.2 644)
@@ -214,6 +214,12 @@ subdir-y += ../acorn/net
 obj-y         += ../acorn/net/acorn-net.o
 endif

+ifeq ($(CONFIG_ARCH_S390),y)
+mod-subdirs   += ../s390/net
+subdir-y += ../s390/net
+obj-y         += ../s390/net/s390-net.o
+endif
+
 #
 # HIPPI adapters
 #



^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 15:46   ` David S. Miller
@ 2001-06-12 16:11     ` Keith Owens
  0 siblings, 0 replies; 16+ messages in thread
From: Keith Owens @ 2001-06-12 16:11 UTC (permalink / raw)
  To: David S. Miller; +Cc: DJBARROW, alan, linux-kernel

On Tue, 12 Jun 2001 08:46:00 -0700 (PDT), 
"David S. Miller" <davem@redhat.com> wrote:
>So, if the s390 folks move their stuff into the appropriate spot it
>will work.  In fact, I personally like to see the s390 net devices
>under drivers/net/s390 anyways.  They'll get free maintenance from
>myself and Jeff Garzik in this way as I rarely look int
>drivers/${PLATFORM} type directories unless I'm doing a tree-wide
>grep. :-)

Leave s390 separate for the moment, all the other architectures work
the same way.

Minimal (and totally untested) patch to compile s390/net as part of the
other network drivers follows - if it's good enough for acorn, it's
good enough for s390.  The method is as ugly as hell but it is the
least possible change for 2.4, major redesign will have to wait for
2.5.  Patch against 2.4.6-pre2.

Index: 6-pre2.1/drivers/s390/Makefile
--- 6-pre2.1/drivers/s390/Makefile Fri, 13 Apr 2001 12:02:38 +1000 kaos (linux-2.4/u/b/43_Makefile 1.3 644)
+++ 6-pre2.1(w)/drivers/s390/Makefile Wed, 13 Jun 2001 02:05:24 +1000 kaos (linux-2.4/u/b/43_Makefile 1.3 644)
@@ -4,7 +4,7 @@
 
 O_TARGET := io.o
 
-subdir-y := block char misc net
+subdir-y := block char misc
 subdir-m := $(subdir-y)
 obj-y := $(foreach dir,$(subdir-y),$(dir)/s390-$(dir).o)
 
@@ -12,3 +12,5 @@ obj-y += s390io.o s390mach.o s390dyn.o i
 export-objs += ccwcache.o idals.o s390dyn.o s390io.o
 
 include $(TOPDIR)/Rules.make
+
+# the NET subdir is included from drivers/net now
Index: 6-pre2.1/drivers/net/Makefile
--- 6-pre2.1/drivers/net/Makefile Thu, 17 May 2001 10:25:35 +1000 kaos (linux-2.4/l/c/26_Makefile 1.1.1.1.3.3.1.1.1.2 644)
+++ 6-pre2.1(w)/drivers/net/Makefile Wed, 13 Jun 2001 02:03:09 +1000 kaos (linux-2.4/l/c/26_Makefile 1.1.1.1.3.3.1.1.1.2 644)
@@ -214,6 +214,12 @@ subdir-y	+= ../acorn/net
 obj-y		+= ../acorn/net/acorn-net.o
 endif
 
+ifeq ($(CONFIG_ARCH_S390),y)
+mod-subdirs	+= ../s390/net
+subdir-y	+= ../s390/net
+obj-y		+= ../s390/net/s390-net.o
+endif
+
 #
 # HIPPI adapters
 #


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 14:57 ` David S. Miller
  2001-06-12 15:34   ` Keith Owens
@ 2001-06-12 15:46   ` David S. Miller
  2001-06-12 16:11     ` Keith Owens
  1 sibling, 1 reply; 16+ messages in thread
From: David S. Miller @ 2001-06-12 15:46 UTC (permalink / raw)
  To: Keith Owens; +Cc: DJBARROW, alan, linux-kernel


Keith Owens writes:
 > David, how do any network drivers that need net_dev_init() work when
 > all $(DRIVERS) come before $(NETWORKS)?  This is a generic problem, not
 > s390 specific.

Then I don't understand why none of the statically built in drivers in
any of my kernels (on any platform I use, sparc64, i386, etc.) make
that "early initialization of device XXX deferred" message get spit
out.

Actually after some studying I do understand :-) net_dev_init() is not
invoked via net/* initialization.  My bad.  It gets invoked from
drivers/block/genhd.c:device_init()  so that is the ordering
dependency and why things work for non-s390 network devices now.

So, if the s390 folks move their stuff into the appropriate spot it
will work.  In fact, I personally like to see the s390 net devices
under drivers/net/s390 anyways.  They'll get free maintenance from
myself and Jeff Garzik in this way as I rarely look int
drivers/${PLATFORM} type directories unless I'm doing a tree-wide
grep. :-)

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 14:57 ` David S. Miller
@ 2001-06-12 15:34   ` Keith Owens
  2001-06-12 15:46   ` David S. Miller
  1 sibling, 0 replies; 16+ messages in thread
From: Keith Owens @ 2001-06-12 15:34 UTC (permalink / raw)
  To: David S. Miller; +Cc: DJBARROW, alan, linux-kernel

On Tue, 12 Jun 2001 07:57:56 -0700 (PDT), 
"David S. Miller" <davem@redhat.com> wrote:
>You need to find a way to link in the S390 network drivers after the
>net/ module so that the drivers run their init after net_dev_init()
>runs.

Tricky.

net_dev_init() is in net/core/dev.c which is linked into
net/core/core.o which is linked into net/network.o which is linked into
vmlinux as part of $(NETWORKS).

drivers/s390/net creates drivers/s390/net/s390-net.o which is linked
into drivers/s390/io.o which is part of $(CORE_FILES), not $(DRIVERS).

$(NETWORKS) is linked _after_ both $(CORE_FILES) and $(DRIVERS).

Have I mentioned recently how much I hate the "link order depends on
Makefile compile order, except where fudged by special case Makefiles"
method?

David, how do any network drivers that need net_dev_init() work when
all $(DRIVERS) come before $(NETWORKS)?  This is a generic problem, not
s390 specific.

AFAICT net_dev_init() needs to be promoted ahead of $(DRIVERS), either
as minimal code or by moving all of $(NETWORKS).  Then moving
drivers/s390/io.o to $(DRIVERS) instead of $(CORE_FILES) will fix the
problem.


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-12 14:17 DJBARROW
@ 2001-06-12 14:57 ` David S. Miller
  2001-06-12 15:34   ` Keith Owens
  2001-06-12 15:46   ` David S. Miller
  0 siblings, 2 replies; 16+ messages in thread
From: David S. Miller @ 2001-06-12 14:57 UTC (permalink / raw)
  To: DJBARROW; +Cc: alan, linux-kernel


DJBARROW@de.ibm.com writes:
 > On 390 it is very easy to hotplug devices under VM.
 > 
 > We do it all the time using the channel device layer on s/390, so users
 > can reconfigure devices if they misconfigure them.
 > 
 > If it can be registered it should be able to be unregistered.
 > 
 > Cornelia Huck in our group in boeblingen noticed the bug too.

I still think it's bogus.  Those "early init of device" messages
should only be occurring for specific legacy ISA device drivers,
and for nothing else.

You need to find a way to link in the S390 network drivers after the
net/ module so that the drivers run their init after net_dev_init()
runs.

Sure, this refcount thing is a bug, and I will look at your patch, but
you need to make your normal net devices get init'd after
net_dev_init() runs.

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
@ 2001-06-12 14:17 DJBARROW
  2001-06-12 14:57 ` David S. Miller
  0 siblings, 1 reply; 16+ messages in thread
From: DJBARROW @ 2001-06-12 14:17 UTC (permalink / raw)
  To: David S. Miller, alan; +Cc: linux-kernel

[-- Attachment #1: Type: text/plain, Size: 1565 bytes --]



Hi Alan/Dave
Here is a better version of the patch I think it cuts about 15 lines out of
dev.c  & I think logically it is more bulletproof than my previous attempt.

(See attached file: dev.c.2.4.5.v2.patch)

Hi Dave,

On 390 it is very easy to hotplug devices under VM.

We do it all the time using the channel device layer on s/390, so users
can reconfigure devices if they misconfigure them.

If it can be registered it should be able to be unregistered.

Cornelia Huck in our group in boeblingen noticed the bug too.



Please respond to "David S. Miller" <davem@redhat.com>

To:   Denis Joseph Barrow/Germany/Contr/IBM@IBMDE
cc:   linux-kernel@vger.kernel.org
Subject:  Re: bug in /net/core/dev.c





DJBARROW@de.ibm.com writes:
 > The dev->refcnt will go up to 2 ( it should be 1) unregister_netdevice
will
 > usually  loop forever
 > waiting for the refcnt to drop to 1 when an attempt to unregister is
done.

When will devices built statically into the kernel ever be
unregister'd?

Later,
David S. Miller
davem@redhat.com

Hi,
I found this bug in dev.c

It happens if register_netdevice is called before net_dev_init which can
happen from init functions,
when device drivers are compiled into the kernel.

The dev->refcnt will go up to 2 ( it should be 1) unregister_netdevice will
usually  loop forever
waiting for the refcnt to drop to 1 when an attempt to unregister is done.

The printk in the bootmessages early initialization of device <blah> is
deferred is evidence of this behaviour occuring.

The small patch is below ,hope it is okay for you.

[-- Attachment #2: dev.c.2.4.5.v2.patch --]
[-- Type: application/octet-stream, Size: 2269 bytes --]

--- net/core/dev.old.c	Wed May 30 14:24:47 2001
+++ net/core/dev.c	Tue Jun 12 15:37:58 2001
@@ -20,6 +20,10 @@
  *              Pekka Riikonen <priikone@poesidon.pspt.fi>
  *
  *	Changes:
+ *              D.J. Barrow     :       Fixed bug where dev->refcnt gets set to 2 
+ *                                      if register_netdev gets called before
+ *                                      net_dev_init & also removed a few lines
+ *                                      of code in the process.
  *		Alan Cox	:	device private ioctl copies fields back.
  *		Alan Cox	:	Transmit queue code does relevant stunts to
  *					keep the queue safe.
@@ -2382,6 +2386,7 @@
  *	will not get the same name.
  */
 
+int net_dev_init(void);
 int register_netdevice(struct net_device *dev)
 {
 	struct net_device *d, **dp;
@@ -2396,48 +2401,8 @@
 	dev->fastpath_lock=RW_LOCK_UNLOCKED;
 #endif
 
-	if (dev_boot_phase) {
-#ifdef CONFIG_NET_DIVERT
-		ret = alloc_divert_blk(dev);
-		if (ret)
-			return ret;
-#endif /* CONFIG_NET_DIVERT */
-		
-		/* This is NOT bug, but I am not sure, that all the
-		   devices, initialized before netdev module is started
-		   are sane. 
-
-		   Now they are chained to device boot list
-		   and probed later. If a module is initialized
-		   before netdev, but assumes that dev->init
-		   is really called by register_netdev(), it will fail.
-
-		   So that this message should be printed for a while.
-		 */
-		printk(KERN_INFO "early initialization of device %s is deferred\n", dev->name);
-
-		/* Check for existence, and append to tail of chain */
-		for (dp=&dev_base; (d=*dp) != NULL; dp=&d->next) {
-			if (d == dev || strcmp(d->name, dev->name) == 0) {
-				return -EEXIST;
-			}
-		}
-		dev->next = NULL;
-		write_lock_bh(&dev_base_lock);
-		*dp = dev;
-		dev_hold(dev);
-		write_unlock_bh(&dev_base_lock);
-
-		/*
-		 *	Default initial state at registry is that the
-		 *	device is present.
-		 */
-
-		set_bit(__LINK_STATE_PRESENT, &dev->state);
-
-		return 0;
-	}
-
+	if (dev_boot_phase)
+		net_dev_init();
 #ifdef CONFIG_NET_DIVERT
 	ret = alloc_divert_blk(dev);
 	if (ret)
@@ -2679,7 +2644,9 @@
 {
 	struct net_device *dev, **dp;
 	int i;
-
+	
+	if(!dev_boot_phase)
+		return 0;
 #ifdef CONFIG_NET_SCHED
 	pktsched_init();
 #endif

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: bug in /net/core/dev.c
  2001-06-11 18:32 DJBARROW
@ 2001-06-12  3:18 ` David S. Miller
  0 siblings, 0 replies; 16+ messages in thread
From: David S. Miller @ 2001-06-12  3:18 UTC (permalink / raw)
  To: DJBARROW; +Cc: linux-kernel


DJBARROW@de.ibm.com writes:
 > The dev->refcnt will go up to 2 ( it should be 1) unregister_netdevice will
 > usually  loop forever
 > waiting for the refcnt to drop to 1 when an attempt to unregister is done.

When will devices built statically into the kernel ever be
unregister'd?

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 16+ messages in thread

* bug in /net/core/dev.c
@ 2001-06-11 18:32 DJBARROW
  2001-06-12  3:18 ` David S. Miller
  0 siblings, 1 reply; 16+ messages in thread
From: DJBARROW @ 2001-06-11 18:32 UTC (permalink / raw)
  To: linux-kernel

[-- Attachment #1: Type: text/plain, Size: 776 bytes --]




Hi,
I found this bug in dev.c

It happens if register_netdevice is called before net_dev_init which can
happen from init functions,
when device drivers are compiled into the kernel.

The dev->refcnt will go up to 2 ( it should be 1) unregister_netdevice will
usually  loop forever
waiting for the refcnt to drop to 1 when an attempt to unregister is done.

The printk in the bootmessages early initialization of device <blah> is
deferred is evidence of this behaviour occuring.

The small patch is below ,hope it is okay for you.

(See attached file: dev.c.2.4.5.patch)

D.J. Barrow Gnu/Linux for S/390 kernel developer
eMail: djbarrow@de.ibm.com,barrow_dj@yahoo.com
Phone: +49-(0)7031-16-2583
IBM Germany Lab, Schönaicherstr. 220, 71032 Böblingen

[-- Attachment #2: dev.c.2.4.5.patch --]
[-- Type: application/octet-stream, Size: 900 bytes --]

--- net/core/dev.old.c	Mon Jun 11 20:00:42 2001
+++ net/core/dev.c	Mon Jun 11 19:51:55 2001
@@ -20,6 +20,9 @@
  *              Pekka Riikonen <priikone@poesidon.pspt.fi>
  *
  *	Changes:
+ *              D.J. Barrow     :       Fixed net_dev_init calling dev_hold & setting
+ *                                      The dev->refcnt to 2 if register_netdev gets 
+ *                                      called first & initialization is deferred.
  *		Alan Cox	:	device private ioctl copies fields back.
  *		Alan Cox	:	Transmit queue code does relevant stunts to
  *					keep the queue safe.
@@ -2733,8 +2736,10 @@
 #endif
 		dev->xmit_lock_owner = -1;
 		dev->iflink = -1;
-		dev_hold(dev);
-
+		/* Can't do dev_hold here in case
+		 *  register_netdev gets called first.
+		 */
+		atomic_set(&dev->refcnt,1);
 		/*
 		 * Allocate name. If the init() fails
 		 * the name will be reissued correctly.

^ permalink raw reply	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2001-06-13 10:18 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2001-06-13 10:03 bug in /net/core/dev.c DJBARROW
2001-06-13 10:18 ` David S. Miller
  -- strict thread matches above, loose matches on Subject: below --
2001-06-12 18:38 DJBARROW
2001-06-12 18:44 ` David S. Miller
2001-06-12 17:05 Ulrich.Weigand
2001-06-12 17:20 ` Keith Owens
2001-06-12 16:43 DJBARROW
2001-06-12 16:51 ` David S. Miller
2001-06-12 17:02 ` Keith Owens
2001-06-12 14:17 DJBARROW
2001-06-12 14:57 ` David S. Miller
2001-06-12 15:34   ` Keith Owens
2001-06-12 15:46   ` David S. Miller
2001-06-12 16:11     ` Keith Owens
2001-06-11 18:32 DJBARROW
2001-06-12  3:18 ` David S. Miller

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