Michal Marek <mmarek@xxxxxxx> writes: > On 2014-07-11 13:51, Rasmus Villemoes wrote: >> Hi, >> >> gcc/cpp claims to be smart enough to recognize the include guard idiom, >> and most of the time this works very well: the second and subsequent >> #includes do not even cause the file to be opened (thus saving at least >> open+fstat+read+close). Except in a few cases, which are so common that >> it might be worth investigating. >> >> For example, linux/mm.h often shows up exactly twice in strace output; >> another very common header such as linux/types.h always occurs only >> once. > > My guess is that <linux/mm.h> includes a header which at some point > includes <linux/mm.h> again. Indeed. I naively thought that the kernel didn't have any cyclic includes, but if ever I was wrong about something... The cycle is very short (mm.h and vmstat.h include each other). Including vmstat.h before mm.h breaks the build. Thanks for enlightening me, Rasmus -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
