On Tue, 2024-10-22 at 15:55 +0200, Greg Kroah-Hartman wrote: > On Tue, Oct 22, 2024 at 03:18:34PM +0200, Johannes Berg wrote: > > From: Johannes Berg <johannes.berg@xxxxxxxxx> > > > > As struct file_operations is really big, but (most) debugfs > > files only use simple_open, read, write and perhaps seek, and > > don't need anything else, this wastes a lot of space for NULL > > pointers. > > > > Add a struct debugfs_short_fops and some bookkeeping code in > > debugfs so that users can use that with debugfs_create_file() > > using _Generic to figure out which function to use. > > > > Converting mac80211 to use it where possible saves quite a > > bit of space: > > > > 1010127 205064 1220 1216411 128f9b net/mac80211/mac80211.ko (before) > > 981199 205064 1220 1187483 121e9b net/mac80211/mac80211.ko (after) > > ------- > > -28928 = ~28KiB > > > > With a marginal space cost in debugfs: > > > > 8701 550 16 9267 2433 fs/debugfs/inode.o (before) > > 25233 325 32 25590 63f6 fs/debugfs/file.o (before) > > 8914 558 16 9488 2510 fs/debugfs/inode.o (after) > > 25380 325 32 25737 6489 fs/debugfs/file.o (after) > > --------------- > > +360 +8 > > > > (All on x86-64) > > > > A simple spatch suggests there are more than 300 instances, > > not even counting the ones hidden in macros like in mac80211, > > that could be trivially converted, for additional savings of > > about 240 bytes for each. > > > > Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> > > I imagine you want to take this through the wireless tree for the second > patch, so feel free to do that and add: I don't even really care, we're not likely to be changing the mac80211 debugfs code in a way that'd create (significant) conflicts. But I can do that, thanks! johannes
