Thread (2 messages) flat view 2 messages, 2 authors, 2015-05-30

Re: [PATCH 49/98] Break dependency loop between linux/if.h and linux/hdlc/ioctl.h

From: Frans Klaver <hidden>
Date: 2015-05-30 19:51:55
Also in: lkml

On Sat, May 30, 2015 at 05:38:41PM +0200, Mikko Rapeli wrote:
quoted hunk ↗ jump to hunk
This isn't pretty but does the job. I assume including plain linux/hdlc/ioctl.h
without linux/if.h is much more rare than the other way round, and that
these header file names are part of API, and that creating a new header file
just for IFNAMSIZ isn't a good idea either.

Fixes userspace compiler error:

error: ‘IFNAMSIZ’ undeclared here (not in a function)

Signed-off-by: Mikko Rapeli <redacted>
---
 include/uapi/linux/hdlc/ioctl.h | 5 ++++-
 include/uapi/linux/if.h         | 4 ++++
 2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/hdlc/ioctl.h b/include/uapi/linux/hdlc/ioctl.h
index 8bbee11..73982ec 100644
--- a/include/uapi/linux/hdlc/ioctl.h
+++ b/include/uapi/linux/hdlc/ioctl.h
@@ -1,7 +1,10 @@
 #ifndef __HDLC_IOCTL_H__
 #define __HDLC_IOCTL_H__
 
-#include <linux/if.h>
+/* For breaking dependency loop between if.h and hdlc/ioctl.h */
+#ifndef IFNAMSIZ
+#define IFNAMSIZ        16
+#endif
 
 #define GENERIC_HDLC_VERSION 4	/* For synchronization with sethdlc utility */
 
diff --git a/include/uapi/linux/if.h b/include/uapi/linux/if.h
index 9cf2394..e4b130a 100644
--- a/include/uapi/linux/if.h
+++ b/include/uapi/linux/if.h
@@ -23,6 +23,10 @@
 #include <linux/socket.h>		/* for "struct sockaddr" et al	*/
 #include <linux/compiler.h>		/* for "__user" et al           */
 
+/**
+ * IFNAMSIZ is also defined in linux/hdlc/ioctl.h if it does not exists
+ * to break dependency loop between linux/if.h and linux/hdlc/ioctl.h.
+ */
 #define	IFNAMSIZ	16
 #define	IFALIASZ	256
 #include <linux/hdlc/ioctl.h>
This feels backwards to me. Wouldn't it be less funky to accept that
IFNAMSIZE isn't defined in if.h, but rather in hdlc/ioctl.h? If now
someone feels giddy and does

#include <linux/hdlc/ioctl.h>
#include <linux/if.h>

We have a new and unnecessary warning on our hands ;-)

Thanks,
Frans
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