linux.git/drivers/char/mem.c, branch v2.6.20

Revert "[PATCH] Fix up mmap_kmem"

2007-01-22T16:53:24+00:00

This reverts commit 99a10a60ba9bedcf5d70ef81414d3e03816afa3f.

As per Hugh Dickins:

  "Nadia Derbey has reported that mmap of /dev/kmem no longer works with
   the kernel virtual address as offset, and Franck has confirmed that
   his patch came from a misunderstanding of what an offset means to
   /dev/kmem - whereas his patch description seems to say that he was
   correcting the offset on a few plaforms, there was no such problem to
   correct, and his patch was in fact changing its API on all platforms."

Suggested-by: Hugh Dickins 
Cc: Franck Bui-Huu 
Cc: Nadia Derbey 
Cc: Andi Kleen 
Cc: Arjan van de Ven 
Cc: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] read_zero_pagealigned() locking fix

2006-12-10T17:55:39+00:00

Ramiro Voicu hits the BUG_ON(!pte_none(*pte)) in zeromap_pte_range: kernel
bugzilla 7645.  Right: read_zero_pagealigned uses down_read of mmap_sem,
but another thread's racing read of /dev/zero, or a normal fault, can
easily set that pte again, in between zap_page_range and zeromap_page_range
getting there.  It's been wrong ever since 2.4.3.

The simple fix is to use down_write instead, but that would serialize reads
of /dev/zero more than at present: perhaps some app would be badly
affected.  So instead let zeromap_page_range return the error instead of
BUG_ON, and read_zero_pagealigned break to the slower clear_user loop in
that case - there's no need to optimize for it.

Use -EEXIST for when a pte is found: BUG_ON in mmap_zero (the other user of
zeromap_page_range), though it really isn't interesting there.  And since
mmap_zero wants -EAGAIN for out-of-memory, the zeromaps better return that
than -ENOMEM.

Signed-off-by: Hugh Dickins 
Cc: Ramiro Voicu: 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] struct path: convert char-drivers

2006-12-08T16:28:44+00:00

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

Driver core: change mem class_devices to be real devices

2006-12-01T22:52:00+00:00

Signed-off-by: Greg Kroah-Hartman

Include proper header file for PFN_DOWN()

2006-10-13T15:42:10+00:00

The recent commit (99a10a60ba9bedcf5d70ef81414d3e03816afa3f) to fix up
mmap_kmem() broke compiles because it used PFN_DOWN() without including
.

Signed-off-by: Linus Torvalds

[PATCH] Fix up mmap_kmem

2006-10-13T15:35:38+00:00

vma->vm_pgoff is an pfn _offset_ relatif to the begining
of the memory start. The previous code was doing at first:

	vma->vm_pgoff << PAGE_SHIFT

which results into a wrong physical address since some
platforms have a physical mem start that can be different
from 0. After that the previous call __pa() on this
wrong physical address, however __pa() is used to convert
a _virtual_ address into a physical one.

This patch rewrites this convertion. It calculates the
pfn of PAGE_OFFSET which is the pfn of the mem start
then it adds the vma->vm_pgoff to it.

It also uses virt_to_phys() instead of __pa() since the
latter shouldn't be used by drivers.

Signed-off-by: Franck Bui-Huu 
Signed-off-by: Linus Torvalds

[PATCH] mem driver: fix conditional on isa i/o support

2006-09-29T16:18:22+00:00

This change corrects the logic on the preprocessor conditionals that
include support for ISA port i/o (/dev/ioports) into the mem character
driver.

This fixes the following error when building for powerpc platforms with
CONFIG_PCI=n.

  drivers/built-in.o: undefined reference to `pci_io_base'

Signed-off-by: Geoff Levand 
Acked-by: Linas Vepstas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] NOMMU: Set BDI capabilities for /dev/mem and /dev/kmem

2006-09-27T15:26:14+00:00

Set the backing device info capabilities for /dev/mem and /dev/kmem to
permit direct sharing under no-MMU conditions and full mapping capabilities
under MMU conditions.  Make the BDI used by these available to all directly
mappable character devices.

Also comment the capabilities for /dev/zero.

[akpm@osdl.org: ifdef reductions]
Signed-off-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] make valid_mmap_phys_addr_range() take a pfn

2006-07-10T20:24:25+00:00

Newer ARMs have a 40 bit physical address space, but mapping physical
memory above 4G needs a special page table format which we (currently?) do
not use for userspace mappings, so what happens instead is that mapping an
address >= 4G will happily discard the upper bits and wrap.

There is a valid_mmap_phys_addr_range() arch hook where we could check for
>= 4G addresses and deny the mapping, but this hook takes an unsigned long
address:

	static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size);

And drivers/char/mem.c:mmap_mem() calls it like this:

	static int mmap_mem(struct file * file, struct vm_area_struct * vma)
	{
		size_t size = vma->vm_end - vma->vm_start;

		if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))

So that's not much help either.

This patch makes the hook take a pfn instead of a phys address.

Signed-off-by: Lennert Buytenhek 
Cc: Bjorn Helgaas 
Cc: "Luck, Tony" 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] make more file_operation structs static

2006-07-03T22:26:59+00:00

Mark the static struct file_operations in drivers/char as const.  Making
them const prevents accidental bugs, and moves them to the .rodata section
so that they no longer do any false sharing; in addition with the proper
debug option they are then protected against corruption..

[akpm@osdl.org: build fix]
Signed-off-by: Arjan van de Ven 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds