Backporting kfree_rcu() in compat does not work as
struct rcu_head->func is always interpreted as a pointer in older
kernel versions, but when using kfree_rcu() it is set to an offset.
rcu_head->func is used in some functions in the kernel not backported
by compat-wireless.
In older kernel versions in __rcu_reclaim just the else path is available.
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
include/linux/compat-2.6.40.h | 58 -----------------------------------------
1 files changed, 0 insertions(+), 58 deletions(-)
diff --git a/include/linux/compat-2.6.40.h b/include/linux/compat-2.6.40.h
index 9ec8c1b..b3fc8f7 100644
--- a/include/linux/compat-2.6.40.h
+++ b/include/linux/compat-2.6.40.h
@@ -24,64 +24,6 @@
#define br_port_exists(dev) (dev->br_port)
#endif
-static __always_inline bool __is_kfree_rcu_offset(unsigned long offset)
-{
- return offset < 4096;
-}
-
-static __always_inline
-void __kfree_rcu(struct rcu_head *head, unsigned long offset)
-{
- typedef void (*rcu_callback)(struct rcu_head *);
-
- /* This causes build failures with some kernel versions at positions
- * where this methods is not used at all.
- */
- /* BUILD_BUG_ON(!__builtin_constant_p(offset)); */
-
- /* See the kfree_rcu() header comment. */
- /* BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); */
-
- call_rcu(head, (rcu_callback)offset);
-}
-
-static inline void __rcu_reclaim(struct rcu_head *head)
-{
- unsigned long offset = (unsigned long)head->func;
-
- if (__is_kfree_rcu_offset(offset))
- kfree((void *)head - offset);
- else
- head->func(head);
-}
-
-/**
- * kfree_rcu() - kfree an object after a grace period.
- * @ptr: pointer to kfree
- * @rcu_head: the name of the struct rcu_head within the type of @ptr.
- *
- * Many rcu callbacks functions just call kfree() on the base structure.
- * These functions are trivial, but their size adds up, and furthermore
- * when they are used in a kernel module, that module must invoke the
- * high-latency rcu_barrier() function at module-unload time.
- *
- * The kfree_rcu() function handles this issue. Rather than encoding a
- * function address in the embedded rcu_head structure, kfree_rcu() instead
- * encodes the offset of the rcu_head structure within the base structure.
- * Because the functions are not allowed in the low-order 4096 bytes of
- * kernel virtual memory, offsets up to 4095 bytes can be accommodated.
- * If the offset is larger than 4095 bytes, a compile-time error will
- * be generated in __kfree_rcu(). If this error is triggered, you can
- * either fall back to use of call_rcu() or rearrange the structure to
- * position the rcu_head structure into the first 4096 bytes.
- *
- * Note that the allowable offset might decrease in the future, for example,
- * to allow something like kmem_cache_free_rcu().
- */
-#define kfree_rcu(ptr, rcu_head) \
- __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
-
-
#endif /* (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,40)) */
#endif /* LINUX_26_40_COMPAT_H */
--
1.7.4.1
--
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