fixeria has uploaded this change for review. (
https://gerrit.osmocom.org/c/libosmocore/+/43151?usp=email )
Change subject: linuxlist: drop no-op prefetch() calls
......................................................................
linuxlist: drop no-op prefetch() calls
prefetch() has always been a no-op stub in this header so calling
it buys nothing at runtime. Drop all call sites and remove the
now-dead stub itself.
The macro was copied over from the Linux kernel, where prefetch()
is a real, arch-specific cache prefetch hint; here it never was
anything but an empty inline function.
Change-Id: Id84973330df44b4efdd1bd85e4b7c3cb88642f92
Related: OS#7036, OS#6858
---
M include/osmocom/core/linuxlist.h
1 file changed, 16 insertions(+), 29 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/51/43151/1
diff --git a/include/osmocom/core/linuxlist.h b/include/osmocom/core/linuxlist.h
index e5e5075..94191e6 100644
--- a/include/osmocom/core/linuxlist.h
+++ b/include/osmocom/core/linuxlist.h
@@ -22,8 +22,6 @@
#define inline __inline__
#endif
-static inline void prefetch(const void *x) {;}
-
/*! Cast a member of a structure out to the containing structure.
* \param[in] ptr the pointer to the member.
* \param[in] type the type of the container struct this is embedded in.
@@ -283,15 +281,13 @@
* \param head the head of the list over which to iterate.
*/
#define llist_for_each(pos, head) \
- for (pos = (head)->next, prefetch(pos->next); pos != (head); \
- pos = pos->next, prefetch(pos->next))
+ for (pos = (head)->next; pos != (head); pos = pos->next)
-/*! Iterate over a linked list (no prefetch).
+/*! Iterate over a linked list.
* \param pos the llist_head to use as a loop counter.
* \param head the head of the list over which to iterate.
*
- * This variant differs from llist_for_each() in that it's the
- * simplest possible llist iteration code, no prefetching is done.
+ * Equivalent to llist_for_each(); kept for API compatibility.
* Use this for code that knows the llist to be very short (empty
* or 1 entry) most of the time.
*/
@@ -303,8 +299,7 @@
* \param head the head of the list over which to iterate.
*/
#define llist_for_each_prev(pos, head) \
- for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
- pos = pos->prev, prefetch(pos->prev))
+ for (pos = (head)->prev; pos != (head); pos = pos->prev)
/*! Iterate over a linked list, safe against removal of llist entry.
* \param pos the llist_head to use as a loop counter.
@@ -321,11 +316,9 @@
* \param member the name of the llist_head within the struct pos.
*/
#define llist_for_each_entry(pos, head, member)
\
- for (pos = llist_entry((head)->next, typeof(*pos), member), \
- prefetch(__llist_member(pos, member)->next); \
+ for (pos = llist_entry((head)->next, typeof(*pos), member); \
__llist_member(pos, member) != (head); \
- pos = llist_entry(__llist_member(pos, member)->next, typeof(*pos),
member), \
- prefetch(__llist_member(pos, member)->next))
+ pos = llist_entry(__llist_member(pos, member)->next, typeof(*pos),
member))
/*! Iterate backwards over a linked list of a given type.
* \param pos the 'type *' to use as a loop counter.
@@ -333,11 +326,9 @@
* \param member the name of the llist_head within the struct pos.
*/
#define llist_for_each_entry_reverse(pos, head, member)
\
- for (pos = llist_entry((head)->prev, typeof(*pos), member), \
- prefetch(__llist_member(pos, member)->prev); \
+ for (pos = llist_entry((head)->prev, typeof(*pos), member); \
__llist_member(pos, member) != (head); \
- pos = llist_entry(__llist_member(pos, member)->prev, typeof(*pos),
member), \
- prefetch(__llist_member(pos, member)->prev))
+ pos = llist_entry(__llist_member(pos, member)->prev, typeof(*pos),
member))
/*! Iterate over a linked list of a given type,
* continuing after an existing point.
@@ -346,11 +337,9 @@
* \param member the name of the llist_head within the struct pos.
*/
#define llist_for_each_entry_continue(pos, head, member) \
- for (pos = llist_entry(pos->member.next, typeof(*pos), member), \
- prefetch(__llist_member(pos, member)->next); \
+ for (pos = llist_entry(pos->member.next, typeof(*pos), member); \
__llist_member(pos, member) != (head); \
- pos = llist_entry(__llist_member(pos, member)->next, typeof(*pos),
member), \
- prefetch(__llist_member(pos, member)->next))
+ pos = llist_entry(__llist_member(pos, member)->next, typeof(*pos),
member))
/*! Iterate over llist of given type, safe against removal of llist entry.
* \param pos the 'type *' to use as a loop counter.
@@ -369,8 +358,8 @@
* \param head the head of the list over which to iterate.
*/
#define llist_for_each_rcu(pos, head) \
- for (pos = (head)->next, prefetch(pos->next); pos != (head); \
- pos = pos->next, ({ smp_read_barrier_depends(); 0;}),
prefetch(pos->next))
+ for (pos = (head)->next; pos != (head); \
+ pos = pos->next, ({ smp_read_barrier_depends(); 0;}))
#define __llist_for_each_rcu(pos, head) \
for (pos = (head)->next; pos != (head); \
@@ -391,12 +380,10 @@
* \param member the name of the llist_struct within the struct.
*/
#define llist_for_each_entry_rcu(pos, head, member) \
- for (pos = llist_entry((head)->next, typeof(*pos), member), \
- prefetch(__llist_member(pos, member)->next); \
+ for (pos = llist_entry((head)->next, typeof(*pos), member); \
__llist_member(pos, member) != (head); \
pos = llist_entry(__llist_member(pos, member)->next, typeof(*pos),
member), \
- ({ smp_read_barrier_depends(); 0;}), \
- prefetch(__llist_member(pos, member)->next))
+ ({ smp_read_barrier_depends(); 0;}))
/*! Iterate over an rcu-protected llist, continuing after existing point.
@@ -404,8 +391,8 @@
* \param head the head of the list over which to iterate.
*/
#define llist_for_each_continue_rcu(pos, head) \
- for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \
- (pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}),
prefetch((pos)->next))
+ for ((pos) = (pos)->next; (pos) != (head); \
+ (pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}))
/*! Count number of llist items by iterating.
* \param head the llist head to count items of.
--
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Gerrit-MessageType: newchange
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Change-Id: Id84973330df44b4efdd1bd85e4b7c3cb88642f92
Gerrit-Change-Number: 43151
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria <[email protected]>
