The manual says that it is required and we actually have crash reports
where loads see stale data due to not having membars here.
In one case the networking does:
memset(skb, 0, offsetof(struct sk_buff, truesize));
and then some code later checks skb->nohdr for zero, but it's still
the value that was there before the memset().
Note that arch/sparc64/lib/xor.S already got this right.
Signed-off-by: David S. Miller <davem@davemloft.net>
subcc %o1, 0x100, %o1
bne,pt %xcc, 1b
add %o0, 0x100, %o0
+ membar #Sync
retl
wr %g2, 0x0, %asi
.size NGtsb_init, .-NGtsb_init
bne,pt %xcc, NGbzero_loop
add %o0, 64, %o0
+ membar #Sync
wr %o4, 0x0, %asi
brz,pn %o1, NGbzero_done
NGbzero_medium:
/* fall through */
60:
+ membar #Sync
+
/* %o2 contains any final bytes still needed to be copied
* over. If anything is left, we copy it one byte at a time.
*/
subcc %g7, 64, %g7
bne,pt %xcc, 1b
add %o0, 32, %o0
+ membar #Sync
retl
nop
subcc %g7, 64, %g7
bne,pt %xcc, 1b
add %o0, 32, %o0
+ membar #Sync
retl
nop