On Wed, 2013-04-10 at 19:15 +0200, Johannes Berg wrote: > > Sure, lets what's the idea or do you want to do that on another thread? Let me give it a different subject :-) > It's kinda half-baked and I'm not completely sure it's a good idea > (because we may have to follow header file renames, though they happen > rarely), but I was basically thinking this: > > Say there's > > void my_foo_function(struct foo *f); > > that we want to backport. Let's also say it's defined in <linux/foo.h>, > and that it was usually present starting from kernel 3.0, but for now > let's assume the "foo" subsystem always existed (i.e. <linux/foo.h>) > > Typically, we'd therefore add it to <linux/compat-3.0.h> and declare it > there, maybe with the LINUX_BACKPORT() wrapper, and then define it in > compat/compat-3.0.c. > > What I'm thinking is that we should maybe declare it in compat in > include/linux/foo.h instead, maybe like this: > > #ifndef __BACKPORT_FOO > #define __BACKPORT_FOO > #include_next <linux/foo.h> > > #if LINUX_VERSION < 3.0 > #define my_foo_function LINUX_BACKPORT(my_foo_function) > > void my_foo_function(struct foo *f); > #endif > > #endif /* __BACKPORT_FOO */ > > > > I'm a bit undecided. On the one hand I think it's nice that we can spot > in one place what's backported where in all the > include/linux/compat-xyz.h files, but on the other hand it's kinda > becoming a messy jumble of features across different subsystems, and > hard to determine what you have already and might need for a given > header file? In addition to what I said, I just realized that we should probably do this, and do it consistently even for old things. That way, we can get rid of all the pr_fmt patches. The reason for the pr_fmt patches is that typically, a source file would have #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <whatever, including somehow getting printk.h> Now that we force them to include compat-2.6.h at the very beginning of the file, printk.h already gets included in some way through compat-2.6.h (there are of course MANY MANY paths to it.) To avoid redefine warnings, we thus patch everything to be #undef pr_fmt #define pr_fmt ... which of course works, but it's pretty ugly (we have >1000 patchlines for this!) If we were able to get rid of compat-2.6.h and put all the backports into their appropriate headers (linux/foo.h) we could only force an include of compat_autoconf.h (which doesn't include printk.h of course) and then we'd be able to get rid of all these patches. johannes -- To unsubscribe from this list: send the line "unsubscribe backports" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
