[IA64] Fix race condition in the rt_sigprocmask fastcall
current->blocked will be set to the value of current->thread_info->flags if the
cmpxchg to update thread_info->flags fails. For performance reasons the store into
current->blocked was placed in the cmpxchg loop. However, the cmpxchg overwrites the
register holding the value to be stored. In the rare case of a retry the value of
thread_info->flags will be written into current->blocked.
The fix is to use another register so that the register containing the current->blocked
value is not overwritten.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/fsys.S b/arch/ia64/kernel/fsys.S
index 4f3cdef..962b6c4 100644
--- a/arch/ia64/kernel/fsys.S
+++ b/arch/ia64/kernel/fsys.S
@@ -460,9 +460,9 @@
;;
st8 [r2]=r14 // update current->blocked with new mask
- cmpxchg4.acq r14=[r9],r18,ar.ccv // current->thread_info->flags <- r18
+ cmpxchg4.acq r8=[r9],r18,ar.ccv // current->thread_info->flags <- r18
;;
- cmp.ne p6,p0=r17,r14 // update failed?
+ cmp.ne p6,p0=r17,r8 // update failed?
(p6) br.cond.spnt.few 1b // yes -> retry
#ifdef CONFIG_SMP