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kdump: add is_vmcore_usable() and vmcore_unusable()

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The usage of elfcorehdr_addr has changed recently such that being set to
ELFCORE_ADDR_MAX is used by is_kdump_kernel() to indicate if the code is
executing in a kernel executed as a crash kernel.

However, arch/ia64/kernel/setup.c:reserve_elfcorehdr will rest
elfcorehdr_addr to ELFCORE_ADDR_MAX on error, which means any subsequent
calls to is_kdump_kernel() will return 0, even though they should return
1.

Ok, at this point in time there are no subsequent calls, but I think its
fair to say that there is ample scope for error or at the very least
confusion.

This patch add an extra state, ELFCORE_ADDR_ERR, which indicates that
elfcorehdr_addr was passed on the command line, and thus execution is
taking place in a crashdump kernel, but vmcore can't be used for some
reason.  This is tested for using is_vmcore_usable() and set using
vmcore_unusable().  A subsequent patch makes use of this new code.

To summarise, the states that elfcorehdr_addr can now be in are as follows:

ELFCORE_ADDR_MAX: not a crashdump kernel
ELFCORE_ADDR_ERR: crashdump kernel but vmcore is unusable
any other value:  crash dump kernel and vmcore is usable

Signed-off-by: Simon Horman <horms@verge.net.au>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Simon Horman
2008-10-18 20:28:29 -07:00
committed by Linus Torvalds
parent 630bf20747
commit 85a0ee342e
3 changed files with 27 additions and 3 deletions
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4
arch/ia64/kernel/setup.c
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@ -509,11 +509,11 @@ int __init reserve_elfcorehdr(unsigned long *start, unsigned long *end)
* to work properly.
*/
if (elfcorehdr_addr >= ELFCORE_ADDR_MAX)
if (!is_vmcore_usable())
return -EINVAL;
if ((length = vmcore_find_descriptor_size(elfcorehdr_addr)) == 0) {
elfcorehdr_addr = ELFCORE_ADDR_MAX;
vmcore_unusable();
return -EINVAL;
}