[PATCH] Directed yield: direct yield of spinlocks for s390.

Use the new diagnose 0x9c in the spinlock implementation for s390.  It
yields the remaining timeslice of the virtual cpu that tries to acquire a
lock to the virtual cpu that is the current holder of the lock.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/s390/kernel/head31.S b/arch/s390/kernel/head31.S
index 1fa9fa1ca740..1b952a3664e2 100644
--- a/arch/s390/kernel/head31.S
+++ b/arch/s390/kernel/head31.S
@@ -254,6 +254,16 @@ startup_continue:
         oi      3(%r12),0x80            # set IDTE flag
 .Lchkidte:
 
+#
+# find out if the diag 0x9c is available
+#
+        mvc     __LC_PGM_NEW_PSW(8),.Lpcdiag9c-.LPG1(%r13)
+        stap   __LC_CPUID+4             # store cpu address
+        lh     %r1,__LC_CPUID+4
+        diag   %r1,0,0x9c               # test diag 0x9c
+        oi     2(%r12),1                # set diag9c flag
+.Lchkdiag9c:
+
         lpsw  .Lentry-.LPG1(13)         # jump to _stext in primary-space,
                                         # virtual and never return ...
         .align  8
@@ -281,6 +291,7 @@ startup_continue:
 .Lpccsp:.long   0x00080000,0x80000000 + .Lchkcsp
 .Lpcmvpg:.long  0x00080000,0x80000000 + .Lchkmvpg
 .Lpcidte:.long  0x00080000,0x80000000 + .Lchkidte
+.Lpcdiag9c:.long 0x00080000,0x80000000 + .Lchkdiag9c
 .Lmemsize:.long memory_size
 .Lmchunk:.long  memory_chunk
 .Lmflags:.long  machine_flags