[rdma-core,3/8] verbs: Use cmake to detect if net/if.h vs netling/route/link.h is broken

Commit Message

Jason Gunthorpe Oct. 14, 2016, 10:14 p.m. UTC

If not then just use the header directly, otherwise use the work around.

The issue is that old libnl libraries include linux/if.h and the
declarations there conflict with net/if.h. New libraries do not
do this.

Signed-off-by: Jason Gunthorpe <[e-mail]>
---
 CMakeLists.txt       | 16 ++++++++++++++++
 buildlib/config.h.in |  2 ++
 libibverbs/neigh.c   |  5 +++--
 3 files changed, 21 insertions(+), 2 deletions(-)

Comments

Steve Wise Oct. 17, 2016, 2:48 p.m. UTC | #1

> Subject: [PATCH rdma-core 3/8] verbs: Use cmake to detect if net/if.h vs
> netling/route/link.h is broken

nit: netling -> netlink



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Patch

diff --git a/CMakeLists.txt b/CMakeLists.txt
index bede766adf4d..58de78d6cde0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -210,6 +210,18 @@  else()
   set(NL_LIBRARIES "")
 endif()
 
+# Older stuff blows up if these headers are included together
+if (NOT NL_KIND EQUAL 0)
+  set(SAFE_CMAKE_REQUIRED_INCLUDES "${CMAKE_REQUIRED_INCLUDES}")
+  set(CMAKE_REQUIRED_INCLUDES "${NL_INCLUDE_DIRS}")
+  CHECK_C_SOURCE_COMPILES("
+#include <netlink/route/link.h>
+#include <net/if.h>
+ int main(int argc,const char *argv[]) {return 0;}"
+    HAVE_WORKING_IF_H)
+  set(CMAKE_REQUIRED_INCLUDES "${SAFE_CMAKE_REQUIRED_INCLUDES}")
+endif()
+
 # Statically determine sizeof(long), this is largely unnecessary, no new code
 # should rely on this.
 check_type_size("long" SIZEOF_LONG BUILTIN_TYPES_ONLY LANGUAGE C)
@@ -325,6 +337,10 @@  if (NL_KIND EQUAL 1)
 endif()
 if (NL_KIND EQUAL 0)
   message(STATUS " neighbour resolution NOT enabled")
+else()
+  if (NOT HAVE_WORKING_IF_H)
+    message(STATUS " netlink/route/link.h and net/if.h NOT co-includable (old headers)")
+  endif()
 endif()
 if (NOT HAVE_RDMA_USER_RXE)
   message(STATUS " rdma/rdma_user_rxe.h NOT found (old system kernel headers)")
diff --git a/buildlib/config.h.in b/buildlib/config.h.in
index 99103b779baf..23781807bce8 100644
--- a/buildlib/config.h.in
+++ b/buildlib/config.h.in
@@ -31,6 +31,8 @@ 
 // FIXME This has been supported in compilers forever, we should just fail to build on such old systems.
 #cmakedefine HAVE_FUNC_ATTRIBUTE_ALWAYS_INLINE 1
 
+#cmakedefine HAVE_WORKING_IF_H 1
+
 @SIZEOF_LONG_CODE@
 
 #if @NL_KIND@ == 3
diff --git a/libibverbs/neigh.c b/libibverbs/neigh.c
index 5acfcf06fcde..67a83eb0fd27 100644
--- a/libibverbs/neigh.c
+++ b/libibverbs/neigh.c
@@ -20,10 +20,11 @@ 
 #include <ifaddrs.h>
 #include <netdb.h>
 #include <assert.h>
-#ifndef _LINUX_IF_H
+#if HAVE_WORKING_IF_H
 #include <net/if.h>
 #else
-/*Workaround when there's a collision between the includes */
+/* We need this decl from net/if.h but old systems do not let use co-include
+   net/if.h and netlink/route/link.h */
 extern unsigned int if_nametoindex(__const char *__ifname) __THROW;
 #endif