[lkml]   [2008]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Subjectwhose job is it to include various header files?

more a philosophy question than anything but, while poking around
the percpu stuff today, i noticed in the header file linux/percpu.h
the opening snippet:

#include <linux/preempt.h>
#include <linux/slab.h> /* For kmalloc() */
#include <linux/smp.h>
#include <linux/string.h> /* For memset() */
#include <linux/cpumask.h>

hmmm, i thought to myself (because that's how i refer to myself), i
wonder why this header file is including headers for kmalloc() and
memset() when this header file makes no reference to those routines.
let's see what happens if i remove them and:

$ make distclean
$ make defconfig [x86]
$ make

... chug chug chug ...

CC arch/x86/kernel/nmi_32.o
arch/x86/kernel/nmi_32.c: In function ‘check_nmi_watchdog’:
arch/x86/kernel/nmi_32.c:81: error: implicit declaration of function ‘kmalloc’
arch/x86/kernel/nmi_32.c:81: error: ‘GFP_KERNEL’ undeclared (first use in this function)
arch/x86/kernel/nmi_32.c:81: error: (Each undeclared identifier is reported only once
arch/x86/kernel/nmi_32.c:81: error: for each function it appears in.)
arch/x86/kernel/nmi_32.c:81: warning: assignment makes pointer from integer without a cast
arch/x86/kernel/nmi_32.c:118: error: implicit declaration of function ‘kfree’
make[1]: *** [arch/x86/kernel/nmi_32.o] Error 1
make: *** [arch/x86/kernel] Error 2

ok, now i know. but that means, of course, that nmi_32.c is
invoking kmalloc() without ever having included the necessary header
file for it -- it's just inheriting that from linux/percpu.h.

doesn't that (sort of) violate the kernel coding style? if a file
somewhere needs the contents of some header file, isn't it that file's
responsibility to explicitly include it, and not quietly realize it's
getting it from elsewhere?


Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry:
Have classroom, will lecture. Waterloo, Ontario, CANADA
 \ /
  Last update: 2008-03-13 23:11    [W:0.128 / U:0.364 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site