[mpich2-dev] [PATCH 1/1] Issue 4120: Fix attr alignment check from MPI_Aint to long alignment

[Jeff Parker]

In the mpi/attr code, there were checks to ensure the attribute was aligned on a void*
boundary.  This check anded the pointer with sizeof(MPI_Aint)-1.  In the case of an
MPI_Aint being 8 bytes, this was forcing the attribute to be on an 8-byte boundary, when
in fact a 4-byte boundary would do.  Changed the and operation to use sizeof(long)-1 instead.

Signed-off-by: Jeff Parker <jjparker at us.ibm.com>
---
 lib/mpi/mpich2/src/mpi/attr/attr_get.c      |    7 +++++--
 lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c |    7 +++++--
 lib/mpi/mpich2/src/mpi/attr/type_get_attr.c |    7 +++++--
 lib/mpi/mpich2/src/mpi/attr/win_get_attr.c  |    9 ++++++---
 4 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/lib/mpi/mpich2/src/mpi/attr/attr_get.c b/lib/mpi/mpich2/src/mpi/attr/attr_get.c
index 095c979..cc39822 100644
--- a/lib/mpi/mpich2/src/mpi/attr/attr_get.c
+++ b/lib/mpi/mpich2/src/mpi/attr/attr_get.c
@@ -93,8 +93,11 @@ int MPI_Attr_get(MPI_Comm comm, int keyval, void *attr_value, int *flag)
 	       int when the address of a pointer (or an address-sized int)
 	       should have been used.  We can test for this specific
 	       case.  Note that this code assumes sizeof(MPI_Aint) is 
-	       a power of 2. */
-	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attr_value & (sizeof(MPI_Aint)-1)) {
+	       a power of 2. Note that this formerly used MPI_Aint for the
+               address sized int, but since this is configurable and could
+               be larger than a pointer, we use long for the check, since
+               long is expected to be the size of a pointer.*/
+	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attr_value & (sizeof(long)-1)) {
 		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
 	    }
 #           endif
diff --git a/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c b/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
index ce5c836..b243968 100644
--- a/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
+++ b/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
@@ -85,8 +85,11 @@ int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval, void *attribute_val, int *
 	       int when the address of a pointer (or an address-sized int)
 	       should have been used.  We can test for this specific
 	       case.  Note that this code assumes sizeof(MPI_Aint) is 
-	       a power of 2. */
-	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(MPI_Aint)-1)) {
+	       a power of 2. Note that this formerly used MPI_Aint for the
+               address sized int, but since this is configurable and could
+               be larger than a pointer, we use long for the check, since
+               long is expected to be the size of a pointer. */
+	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(long)-1)) {
 		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
 	    }
 #           endif
diff --git a/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c b/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
index 7547bbb..7a41051 100644
--- a/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
+++ b/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
@@ -87,8 +87,11 @@ int MPI_Type_get_attr(MPI_Datatype type, int type_keyval, void *attribute_val,
 	       int when the address of a pointer (or an address-sized int)
 	       should have been used.  We can test for this specific
 	       case.  Note that this code assumes sizeof(MPI_Aint) is 
-	       a power of 2. */
-	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(MPI_Aint)-1)) {
+	       a power of 2. Note that this formerly used MPI_Aint for the
+               address sized int, but since this is configurable and could
+               be larger than a pointer, we use long for the check, since
+               long is expected to be the size of a pointer. */
+	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(long)-1)) {
 		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
 	    }
 #           endif
diff --git a/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c b/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
index 5fbef66..921f018 100644
--- a/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
+++ b/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
@@ -82,9 +82,12 @@ int MPI_Win_get_attr(MPI_Win win, int win_keyval, void *attribute_val,
             /* A common user error is to pass the address of a 4-byte
 	       int when the address of a pointer (or an address-sized int)
 	       should have been used.  We can test for this specific
-	       case.  Note that this code assumes sizeof(MPI_Aint) is 
-	       a power of 2. */
-	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(MPI_Aint)-1)) {
+	       case.  Note that this code assumes sizeof(long) is 
+	       a power of 2. Note that this formerly used MPI_Aint for the
+               address sized int, but since this is configurable and could
+               be larger than a pointer, we use long for the check, since
+               long is expected to be the size of a pointer. */
+	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof(long)-1)) {
 		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
 	    }
 #           endif
-- 
1.5.3.7