MDEV-23510: arm64 lf_hashbb-10.3-danielblack-MDEV-23510-arm-lfhash

volatile has no memory barrier schemantics, its for mmaped IO
so lets allow some optimizer gains and stop pretending it helps
with memory atomicity.

The MDEV lists a SEGV an assumption is made that an address was
partially read. As C packs structs strictly and on arm64 the
cache line size is 128, move the 32bit hashnr to the end so
we don't get the *key pointer split across two cache lines.

1 files changed, 3 insertions, 3 deletions

diff --git a/mysys/lf_hash.c b/mysys/lf_hash.c
index 5dbbc17141f..3e9e8ed3e7e 100644
--- a/mysys/lf_hash.c
+++ b/mysys/lf_hash.c
@@ -31,10 +31,10 @@
 
 /* An element of the list */
 typedef struct {
-  intptr volatile link; /* a pointer to the next element in a list and a flag */
-  uint32 hashnr;        /* reversed hash number, for sorting                 */
+  intptr link;   /* a pointer to the next element in a list and a flag */
   const uchar *key;
   size_t keylen;
+  uint32 hashnr; /* reversed hash number, for sorting */
   /*
     data is stored here, directly after the keylen.
     thus the pointer to data is (void*)(slist_element_ptr+1)
@@ -48,7 +48,7 @@ const int LF_HASH_OVERHEAD= sizeof(LF_SLIST);
   in a list) from l_find to l_insert/l_delete
 */
 typedef struct {
-  intptr volatile *prev;
+  intptr *prev;
   LF_SLIST *curr, *next;
 } CURSOR;