linux.git/fs/proc/inode.c, branch v2.6.23

Fix select on /proc files without ->poll

2007-09-12T00:21:20+00:00

Taneli Vähäkangas  reported that commit
786d7e1612f0b0adb6046f19b906609e4fe8b1ba aka "Fix rmmod/read/write races
in /proc entries" broke SBCL + SLIME combo.

The old code in do_select() used DEFAULT_POLLMASK, if couldn't find
->poll handler.  The new code makes ->poll always there and returns 0 by
default, which is not correct.  Return DEFAULT_POLLMASK instead.

Steps to reproduce:

	install emacs, SBCL, SLIME
	emacs
	M-x slime	in *inferior-lisp* buffer
	[watch it doing "Connecting to Swank on port X.."]

Please, apply before 2.6.23.

P.S.: why SBCL can't just read(2) /proc/cpuinfo is a mystery.

Signed-off-by: Alexey Dobriyan 
Cc: T Taneli Vahakangas 
Cc: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Fix procfs compat_ioctl regression

2007-07-29T02:42:22+00:00

It is important to only provide the compat_ioctl method
if the downstream de->proc_fops does too, otherwise this
utterly confuses the logic in fs/compat_ioctl.c and we
end up doing the wrong thing.

Signed-off-by: David S. Miller 
Acked-by: Alexey Dobriyan 
Signed-off-by: Linus Torvalds

mm: Remove slab destructors from kmem_cache_create().

2007-07-20T01:11:58+00:00

Slab destructors were no longer supported after Christoph's
c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been
BUGs for both slab and slub, and slob never supported them
either.

This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).

Signed-off-by: Paul Mundt

Fix rmmod/read/write races in /proc entries

2007-07-16T16:05:39+00:00

Fix following races:
===========================================
1. Write via ->write_proc sleeps in copy_from_user(). Module disappears
   meanwhile. Or, more generically, system call done on /proc file, method
   supplied by module is called, module dissapeares meanwhile.

   pde = create_proc_entry()
   if (!pde)
	return -ENOMEM;
   pde->write_proc = ...
				open
				write
				copy_from_user
   pde = create_proc_entry();
   if (!pde) {
	remove_proc_entry();
	return -ENOMEM;
	/* module unloaded */
   }
				*boom*
==========================================
2. bogo-revoke aka proc_kill_inodes()

  remove_proc_entry		vfs_read
  proc_kill_inodes		[check ->f_op validness]
				[check ->f_op->read validness]
				[verify_area, security permissions checks]
	->f_op = NULL;
				if (file->f_op->read)
					/* ->f_op dereference, boom */

NOTE, NOTE, NOTE: file_operations are proxied for regular files only. Let's
see how this scheme behaves, then extend if needed for directories.
Directories creators in /proc only set ->owner for them, so proxying for
directories may be unneeded.

NOTE, NOTE, NOTE: methods being proxied are ->llseek, ->read, ->write,
->poll, ->unlocked_ioctl, ->ioctl, ->compat_ioctl, ->open, ->release.
If your in-tree module uses something else, yell on me. Full audit pending.

[akpm@linux-foundation.org: build fix]
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Remove SLAB_CTOR_CONSTRUCTOR

2007-05-17T12:23:04+00:00

SLAB_CTOR_CONSTRUCTOR is always specified. No point in checking it.

Signed-off-by: Christoph Lameter 
Cc: David Howells 
Cc: Jens Axboe 
Cc: Steven French 
Cc: Michael Halcrow 
Cc: OGAWA Hirofumi 
Cc: Miklos Szeredi 
Cc: Steven Whitehouse 
Cc: Roman Zippel 
Cc: David Woodhouse 
Cc: Dave Kleikamp 
Cc: Trond Myklebust 
Cc: "J. Bruce Fields" 
Cc: Anton Altaparmakov 
Cc: Mark Fasheh 
Cc: Paul Mackerras 
Cc: Christoph Hellwig 
Cc: Jan Kara 
Cc: David Chinner 
Cc: "David S. Miller" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: remove pathetic ->deleted WARN_ON

2007-05-08T18:15:02+00:00

WARN_ON(de && de->deleted); is sooo unreliable. Why?

proc_lookup				remove_proc_entry
===========				=================
lock_kernel();
spin_lock(&proc_subdir_lock);
[find proc entry]
spin_unlock(&proc_subdir_lock);
					spin_lock(&proc_subdir_lock);
					[find proc entry]

proc_get_inode
==============
WARN_ON(de && de->deleted);			...

					if (!atomic_read(&de->count))
						free_proc_entry(de);
					else
						de->deleted = 1;

So, if you have some strange oops [1], and doesn't see this WARN_ON it means
nothing.

[1] try_module_get() of module which doesn't exist, two lines below
    should suffice, or not?

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Fix race between proc_get_inode() and remove_proc_entry()

2007-05-08T18:15:01+00:00

proc_lookup				remove_proc_entry
===========				=================

lock_kernel();
spin_lock(&proc_subdir_lock);
[find PDE with refcount 0]
spin_unlock(&proc_subdir_lock);
					spin_lock(&proc_subdir_lock);
					[find PDE with refcount 0]
					[check refcount and free PDE]
					spin_unlock(&proc_subdir_lock);
proc_get_inode:
	de_get(de); /* boom */

Signed-off-by: Alexey Dobriyan 
Cc: "Eric W. Biederman" 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

slab allocators: Remove SLAB_DEBUG_INITIAL flag

2007-05-07T19:12:57+00:00

I have never seen a use of SLAB_DEBUG_INITIAL.  It is only supported by
SLAB.

I think its purpose was to have a callback after an object has been freed
to verify that the state is the constructor state again?  The callback is
performed before each freeing of an object.

I would think that it is much easier to check the object state manually
before the free.  That also places the check near the code object
manipulation of the object.

Also the SLAB_DEBUG_INITIAL callback is only performed if the kernel was
compiled with SLAB debugging on.  If there would be code in a constructor
handling SLAB_DEBUG_INITIAL then it would have to be conditional on
SLAB_DEBUG otherwise it would just be dead code.  But there is no such code
in the kernel.  I think SLUB_DEBUG_INITIAL is too problematic to make real
use of, difficult to understand and there are easier ways to accomplish the
same effect (i.e.  add debug code before kfree).

There is a related flag SLAB_CTOR_VERIFY that is frequently checked to be
clear in fs inode caches.  Remove the pointless checks (they would even be
pointless without removeal of SLAB_DEBUG_INITIAL) from the fs constructors.

This is the last slab flag that SLUB did not support.  Remove the check for
unimplemented flags from SLUB.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sysctl: reimplement the sysctl proc support

2007-02-14T16:10:00+00:00

With this change the sysctl inodes can be cached and nothing needs to be done
when removing a sysctl table.

For a cost of 2K code we will save about 4K of static tables (when we remove
de from ctl_table) and 70K in proc_dir_entries that we will not allocate, or
about half that on a 32bit arch.

The speed feels about the same, even though we can now cache the sysctl
dentries :(

We get the core advantage that we don't need to have a 1 to 1 mapping between
ctl table entries and proc files.  Making it possible to have /proc/sys vary
depending on the namespace you are in.  The currently merged namespaces don't
have an issue here but the network namespace under /proc/sys/net needs to have
different directories depending on which network adapters are visible.  By
simply being a cache different directories being visible depending on who you
are is trivial to implement.

[akpm@osdl.org: fix uninitialised var]
[akpm@osdl.org: fix ARM build]
[bunk@stusta.de: make things static]
Signed-off-by: Eric W. Biederman 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Mark struct super_operations const

2007-02-12T17:48:47+00:00

This patch is inspired by Arjan's "Patch series to mark struct
file_operations and struct inode_operations const".

Compile tested with gcc & sparse.

Signed-off-by: Josef 'Jeff' Sipek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds