We can't switch /sys/class or /sys/bus to use this because they are
not creating new kobjects, only linking to the kobjects in /sys/devices.

This only happens if a kobject belongs to a subsystem that has specified
a set of hotplug operations.

Based on work done by Kevin Fleming <kpfleming@cox.net>

I noticed that the usb_set_configuration() code was leaving
endpoints halted ... likely not a problem just now since that
routine can't be used safely except during enumeration, but
better to fix this than not.

So far as I know, "usbfs" was never documented ... so
here's a patch with some text I've had sitting around,
merging it into the other USB kerneldoc.

It should be accurate, down to the warnings about why
not to use several of the calls, though cross-review
with the code would be good too.  A notable omission
is any details on the async APIs.

This patch:

   - Makes "usbnet" pay attention to device descriptors in
     the most common cases; there's less need to embed device
     hardware details.  This lets it work with high speed
     devices, and should help interop with the newer ARM/PXA
     kernels "usb-eth" (same vid/pid, but different endpoints).

   - Adds some new CDC Ethernet support, which is partly enabled:
     the Zaurus SL-5500 code uses it, with the current FRAMING_Z
     flag overriding normal CDC framing on-the-wire.  (Most of
     the other "minidrivers" use CDC framing, except Net1080
     and GeneSys.)

   - Merges a patch from Johannes to recover from some net1080
     framing errors by flushing the fifos ... the chip gets into
     a wierd mode, this makes the link more robust.  (Thanks!)

   - Gets rid of a family of cpu/logfile saturating loops that
     could show up in early stages of disconnect processing,
     while we're getting rx/tx errors continuously since khubd
     hasn't tried to disconnect() us yet.  (Pathological case,
     with lots of logging enabled: khubd never gets scheduled!)

   - Uses deeper queues at high speed, so the host controllers
     can stay busy transferring packets even when IRQs get held
     off for several milliseconds.  That pipelining gives better
     throughput too -- 4x more with one device, says TTCP.

With the possible exception of multicast support, this code
should be a fine replacement to "cdc-ether" ... certainly
its faster for high speed devices.  Some later patch should
likely do a switch-over.  (Which would  also resolve a Zaurus
hotplugging bug:  "cdc-ether" doesn't blacklist it.)

  fixed up the link status detection

Here are two patches that convert the files to use C99 initializers. The
patches are against current BK.

Using cpu_to_le16p on a __u8 variable is wrong, and gives a compile
warning on PPC.  It's better to use cpu_to_le16 in this case.  Here is
a patch to fix it.  Please apply.

  - remove unnecessary calls to usb_set_configuration

  - mutual exclusion between reset() and probe()

into kroah.com:/home/greg/linux/BK/gregkh-2.5

Stops <6> appearing in middles of line and improves output.

into nuts.ninka.net:/home/davem/src/BK/sparc-2.5

1) Use PTREGS_OFF consistently
2) Define it to allocate STACKFRAME_SZ instead of REGWIN_SZ
3) Kill off REGWIN_SZ, replace with sizeof(struct reg_window).

into home.transmeta.com:/home/torvalds/v2.5/linux

into home.transmeta.com:/home/torvalds/v2.5/linux

From: Hua Zhong <hzhong@cisco.com>

The current ext3 totally ignores I/O errors that happened during a
journal_force_commit time, causing user space to falsely believe it has
succeeded, which actually did not.

This patch  checks IO error during  journal_commit_transaction. and aborts
the journal when there is I/O error.

Originally I thought about reporting the error without doing aborting the
journal, but it probably needs a new flag. Aborting the journal seems to be
the easy way to  signal "hey sth is wrong..".

ext3 allocates and frees at least one handle structure for each system call.
kmalloc and kfree are apparent in the profiles.

Adding a slab cache for these objects takes the overhead for a write() from
1.63 microseconds down to 1.56.

For an appending write, ext3_commit_write() will call the expensive
ext3_mark_inode_dirty() twice.  Once in generic_commit_write()'s extension of
i_size and once in ext3_commit_write() itself where i_disksize is updated.

But by updating i_disksize _before_ calling generic_commit_write() these can
be piggybacked.

The patch takes the overhead of a write() from 1.96 microseconds down to
1.63.

ext3_mark_inode_dirty() (and several other callers) use the
ext3_reserve_inode_write() and ext3_mark_ioc_dirty() pair for journalling an
inode's backing block.

Because ext3_reserve_inode_write() gets journalling access to the block there
is no need for ext3_mark_iloc_dirty() to do it as well.

This change reduces the overhead of a write() from 2.7 microseconds to 1.95
on a 2.7G P4.

From: Stephen Tweedie <sct@redhat.com>

The buffer_uptodate flag gets cleared on IO failure, and this can panic jbd
when it tries to write such a buffer.  Relax the panic to be just a warning.

From: Stephen Tweedie <sct@redhat.com>

Add a new form of assert failure in ext3 which allows us to flag events which
are *usually* bugs, but which can be legally triggered in the presence of IO
failures.  Don't panic the kernel on such errors unless we've defined
#JBD_PARANOID_IOFAIL, which will normally be set only for testing purposes.

The big SMP machines are seeing quite some contention in dnotify_parent()
(via vfs_write).  This function is hammering the global dparent_lock.

However we don't actually need a global dparent_lock for pinning down
dentry->d_parent.  We can use dentry->d_lock for this.  That is already being
held across d_move.

This patch speeds up SDET on the 16-way by 5% and wipes dnotify_parent() off
the profiles.

It also uninlines dnofity_parent().

It also uses spin_lock(), which is faster than read_lock().

I'm not sure that we need to take both the source and target dentry's d_lock
in d_move.

The patch also does lots of s/__inline__/inline/ in dcache.h

From: Maneesh Soni <maneesh@in.ibm.com>

Here is a patch to use seqlock for real_lookup race with d_lookup as suggested
by Linus. The race condition can result in duplicate dentry when d_lookup
fails due concurrent d_move in some unrelated directory.

Apart from real_lookup, lookup_hash()->cached_lookup() can also fail due
to same reason. So, for that I am doing the d_lookup again.

Now we have __d_lookup (called from do_lookup() during pathwalk) and
d_lookup which uses seqlock to protect againt rename race.

dcachebench numbers (lower is better) don't have much difference on a 4-way
PIII xeon SMP box.

base-2565
Average usec/iteration  19059.4
Standard Deviation      503.07

base-2565 + seq_lock
Average usec/iteration  18843.2
Standard Deviation      450.57

From: Neil Brown and myself.

Don't do dput() inside read_lock().  It can sleep.

From: Andries.Brouwer@cwi.nl

Make sure structs used by umsdos ioctls do not change size when the size of
dev_t is changed.

From: Andre Landwehr <andre.landwehr@gmx.net>

with / on an IDE harddisk the disks partitions do not appear in
devfs, only the disc device. This is due to rescan_partitions
being called twice and deleting but not re-creating the entries
during the second call.

hch has acked this.

From: Samuel Thibault <Samuel.Thibault@ens-lyon.fr>

There is no way for a braille device driven by brltty (userland root-owned
daemon) to scrollback the virtual console, the only way is to use the pc
keyboard.  A very simple TIOCLINUX ioctl meets this need (tested).

Also add a command for bringing the last console to the top, as keyboard.c's
lastcons() does when pressing alt - down arrow.

This changes the fadvise(FADV_DONTNEED) operation to start async writeout of
any dirty pages in the file.

The thinking is that if the application doesn't want to use those pages in
the future, we may as well get IO underway against them so they can be freed
up on the next call to fadvise().

The POSIX spec does not go into any detail as to whether this is the right or
wrong behaviour.

This provides a nice way for applications whihc are writing streaming data
(the main users of fadvise) to keep the amount of dirty pagecache under
control without having to resort to system-wide VM tuning.

It also provides an "async fsync()".  If the application passes in a length
of zero, fadvise will start async writeout of the pages, but will not
invalidate any of the file's pagecache.