kernel/linux.git/drivers/char/mem.c, branch linux-2.6.18.y

read_zero_pagealigned() locking fix

2007-02-23T23:49:52+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: Signed-off-by: Andrew Morton Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman

[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

Remove obsolete #include

2006-06-30T17:25:36+00:00

Signed-off-by: Jörn Engel Signed-off-by: Adrian Bunk

[PATCH] devfs: Remove the devfs_fs_kernel.h file from the tree

2006-06-26T19:25:08+00:00

Also fixes up all files that #include it. Signed-off-by: Greg Kroah-Hartman

[PATCH] devfs: Remove devfs_mk_cdev() function from the kernel tree

2006-06-26T19:25:07+00:00

Removes the devfs_mk_cdev() function and all callers of it. Signed-off-by: Greg Kroah-Hartman

[PATCH] splice: add ->splice_write support for /dev/null

2006-04-26T12:40:08+00:00

Useful for testing. Signed-off-by: Jens Axboe

[PATCH] mark f_ops const in the inode

2006-03-28T17:16:05+00:00

Mark the f_ops members of inodes as const, as well as fix the ripple-through this causes by places that copy this f_ops and then "do stuff" with it. Signed-off-by: Arjan van de Ven Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] EFI, /dev/mem: simplify efi_mem_attribute_range()

2006-03-26T16:56:54+00:00

Pass the size, not a pointer to the size, to efi_mem_attribute_range(). This function validates memory regions for the /dev/mem read/write/mmap paths. The pointer allows arches to reduce the size of the range, but I think that's unnecessary complexity. Simplifying it will let me use efi_mem_attribute_range() to improve the ia64 ioremap() implementation. Signed-off-by: Bjorn Helgaas Cc: Matt Domsch Cc: "Tolentino, Matthew E" Cc: "Brown, Len" Cc: Andi Kleen Acked-by: "Luck, Tony" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] adjust /dev/{kmem,mem,port} write handlers

2006-03-25T16:22:55+00:00

The /dev/mem and /dev/kmem write handlers weren't fully POSIX compliant in that they wouldn't always force the file pointer to be updated when returning success status. The /dev/port write handler was inconsistent with the /dev/mem and /dev/kmem handlers in that when encountering a -EFAULT condition after already having written a number of items it would return -EFAULT rather than the number of bytes written. Signed-off-by: Jan Beulich Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds