Re: [PATCH] kcov: add missing #include <linux/sched.h>
From: Mark Rutland
Date: Tue Dec 06 2016 - 06:10:02 EST
On Tue, Dec 06, 2016 at 02:56:24PM +0800, Kefeng Wang wrote:
> It is needed by struct task_struct, fixes the following build problem
> with old gcc:
>
> ../kernel/kcov.c: In function â__sanitizer_cov_trace_pcâ:
> ../kernel/kcov.c:66: error: dereferencing pointer to incomplete type
> ......
> ../kernel/kcov.c:239: error: dereferencing pointer to incomplete type
>
It's somewhat confusing to strip the useful part of the error message
(which mentions task struct).
How about:
In __sanitizer_cov_trace_pc we use task_struct and fields within it,
but as we haven't included <linux/sched.h>, it is not guaranteed to be
defined. While we usually happen to acquire the definition through a
transitive include, this is fragile (and hasn't been true in the past,
causing issues with backports).
Include <linux/sched.h> to avoid any fragility.
Either way this looks like a sensible fix/cleanup, so FWIW:
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
It looks like we're missing some other headers (e.g. <linux/export.h>
for EXPORT_SYMBOL(), <linux/preempt.h> for preempt_count() and friends).
It may be worth fixing all of those at once.
Thanks,
Mark.
> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> ---
>
> note:
> - Build error occurred when I backported kcov to an old kernel version
> with an old gcc
>
> kernel/kcov.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/kcov.c b/kernel/kcov.c
> index 30e6d05..3cbb0c8 100644
> --- a/kernel/kcov.c
> +++ b/kernel/kcov.c
> @@ -7,6 +7,7 @@
> #include <linux/fs.h>
> #include <linux/mm.h>
> #include <linux/printk.h>
> +#include <linux/sched.h>
> #include <linux/slab.h>
> #include <linux/spinlock.h>
> #include <linux/vmalloc.h>
> --
> 1.7.12.4
>