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sparc64: Make lock backoff really a NOP on UP builds.

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As noticed by Mikulas Patocka, the backoff macros don't
completely nop out for UP builds, we still get a
branch always and a delay slot nop.

Fix this by making the branch to the backoff spin loop
selective, then we can nop out the spin loop completely.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2010-08-18 22:53:26 -07:00
parent 6ec274750c
commit 0f58189d4a
3 changed files with 22 additions and 17 deletions
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16
arch/sparc/lib/atomic_64.S
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@@ -21,7 +21,7 @@ atomic_add: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@@ -36,7 +36,7 @@ atomic_sub: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@@ -51,7 +51,7 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
add %g1, %o0, %g1
retl
sra %g1, 0, %o0
@@ -66,7 +66,7 @@ atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
sub %g1, %o0, %g1
retl
sra %g1, 0, %o0
@@ -81,7 +81,7 @@ atomic64_add: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@@ -96,7 +96,7 @@ atomic64_sub: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@@ -111,7 +111,7 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
add %g1, %o0, %o0
@@ -126,7 +126,7 @@ atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
sub %g1, %o0, %o0