tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master
head: 61c04572de404e52a655a36752e696bbcb483cf5
commit: 112dc0c8069e5554e0ad29c58228f1e6ca49e13d locking/barriers: Suppress
sparse warnings in lockless_dereference()
date: 8 days ago
reproduce:
# apt-get install sparse
git checkout 112dc0c8069e5554e0ad29c58228f1e6ca49e13d
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__
sparse warnings: (new ones prefixed by >>)
>> include/linux/radix-tree.h:199:16: sparse: expression using sizeof(void)
include/linux/radix-tree.h:199:16: sparse: incompatible types in comparison
expression (different address spaces)
vim +199 include/linux/radix-tree.h
7cf9c2c7 Nick Piggin 2006-12-06 183
7cf9c2c7 Nick Piggin 2006-12-06 184 /**
7cf9c2c7 Nick Piggin 2006-12-06 185 * radix_tree_deref_slot - dereference a
slot
7cf9c2c7 Nick Piggin 2006-12-06 186 * @pslot: pointer to slot,
returned by radix_tree_lookup_slot
7cf9c2c7 Nick Piggin 2006-12-06 187 * Returns: item that was stored in
that slot with any direct pointer flag
7cf9c2c7 Nick Piggin 2006-12-06 188 * removed.
7cf9c2c7 Nick Piggin 2006-12-06 189 *
7cf9c2c7 Nick Piggin 2006-12-06 190 * For use with radix_tree_lookup_slot().
Caller must hold tree at least read
27d20fdd Nick Piggin 2010-11-11 191 * locked across slot lookup and
dereference. Not required if write lock is
27d20fdd Nick Piggin 2010-11-11 192 * held (ie. items cannot be concurrently
inserted).
27d20fdd Nick Piggin 2010-11-11 193 *
27d20fdd Nick Piggin 2010-11-11 194 * radix_tree_deref_retry must be used to
confirm validity of the pointer if
27d20fdd Nick Piggin 2010-11-11 195 * only the read lock is held.
7cf9c2c7 Nick Piggin 2006-12-06 196 */
7cf9c2c7 Nick Piggin 2006-12-06 197 static inline void
*radix_tree_deref_slot(void **pslot)
7cf9c2c7 Nick Piggin 2006-12-06 198 {
27d20fdd Nick Piggin 2010-11-11 @199 return rcu_dereference(*pslot);
7cf9c2c7 Nick Piggin 2006-12-06 200 }
27d20fdd Nick Piggin 2010-11-11 201
27d20fdd Nick Piggin 2010-11-11 202 /**
29c1f677 Mel Gorman 2011-01-13 203 * radix_tree_deref_slot_protected
- dereference a slot without RCU lock but with tree lock held
29c1f677 Mel Gorman 2011-01-13 204 * @pslot: pointer to slot,
returned by radix_tree_lookup_slot
29c1f677 Mel Gorman 2011-01-13 205 * Returns: item that was stored in
that slot with any direct pointer flag
29c1f677 Mel Gorman 2011-01-13 206 * removed.
29c1f677 Mel Gorman 2011-01-13 207 *
:::::: The code at line 199 was first introduced by commit
:::::: 27d20fddc8af539464fc3ba499d6a830054c3bd6 radix-tree: fix RCU bug
:::::: TO: Nick Piggin <npig...@kernel.dk>
:::::: CC: Linus Torvalds <torva...@linux-foundation.org>
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