1. 14 4月, 2010 6 次提交
  2. 13 4月, 2010 5 次提交
  3. 12 4月, 2010 1 次提交
  4. 10 4月, 2010 2 次提交
    • D
      radix_tree_tag_get() is not as safe as the docs make out [ver #2] · ce82653d
      David Howells 提交于
      radix_tree_tag_get() is not safe to use concurrently with radix_tree_tag_set()
      or radix_tree_tag_clear().  The problem is that the double tag_get() in
      radix_tree_tag_get():
      
      		if (!tag_get(node, tag, offset))
      			saw_unset_tag = 1;
      		if (height == 1) {
      			int ret = tag_get(node, tag, offset);
      
      may see the value change due to the action of set/clear.  RCU is no protection
      against this as no pointers are being changed, no nodes are being replaced
      according to a COW protocol - set/clear alter the node directly.
      
      The documentation in linux/radix-tree.h, however, says that
      radix_tree_tag_get() is an exception to the rule that "any function modifying
      the tree or tags (...) must exclude other modifications, and exclude any
      functions reading the tree".
      
      The problem is that the next statement in radix_tree_tag_get() checks that the
      tag doesn't vary over time:
      
      			BUG_ON(ret && saw_unset_tag);
      
      This has been seen happening in FS-Cache:
      
      	https://www.redhat.com/archives/linux-cachefs/2010-April/msg00013.html
      
      To this end, remove the BUG_ON() from radix_tree_tag_get() and note in various
      comments that the value of the tag may change whilst the RCU read lock is held,
      and thus that the return value of radix_tree_tag_get() may not be relied upon
      unless radix_tree_tag_set/clear() and radix_tree_delete() are excluded from
      running concurrently with it.
      Reported-by: NRomain DEGEZ <romain.degez@smartjog.com>
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Acked-by: NNick Piggin <npiggin@suse.de>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ce82653d
    • P
      slab: Generify kernel pointer validation · fc1c1833
      Pekka Enberg 提交于
      As suggested by Linus, introduce a kern_ptr_validate() helper that does some
      sanity checks to make sure a pointer is a valid kernel pointer.  This is a
      preparational step for fixing SLUB kmem_ptr_validate().
      
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Matt Mackall <mpm@selenic.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fc1c1833
  5. 09 4月, 2010 2 次提交
  6. 08 4月, 2010 4 次提交
  7. 07 4月, 2010 10 次提交
  8. 06 4月, 2010 3 次提交
  9. 05 4月, 2010 1 次提交
  10. 04 4月, 2010 6 次提交