[PATCH] kcov: add missing #include <linux/sched.h>

[PATCH] kcov: add missing #include <linux/sched.h>

[Kefeng Wang]

It is needed by struct task_struct, fixes the following build problem
with old gcc:

../kernel/kcov.c: In function ‘__sanitizer_cov_trace_pc’:
../kernel/kcov.c:66: error: dereferencing pointer to incomplete type
	......
../kernel/kcov.c:239: error: dereferencing pointer to incomplete type

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---

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

Re: [PATCH] kcov: add missing #include <linux/sched.h>

[Mark Rutland]

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 ‘__sanitizer_cov_trace_pc’:
> ../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@arm.com>

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@huawei.com>
> ---
> 
> 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
> 

[PATCH] kcov: add more missing include

[Kefeng Wang]

It is fragile that some definitions acquired via transitive
dependencies, as shown in below:

atomic_*        (<linux/atomic.h>)
ENOMEM/EN*      (<linux/errno.h>)
EXPORT_SYMBOL   (<linux/export.h>)
device_initcall (<linux/init.h>)
preempt_*       (<linux/preempt.h>)

Include them to prevent possible issues.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 kernel/kcov.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 3cbb0c8..cc2fa35ca 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -1,11 +1,16 @@
 #define pr_fmt(fmt) "kcov: " fmt
 
 #define DISABLE_BRANCH_PROFILING
+#include <linux/atomic.h>
 #include <linux/compiler.h>
+#include <linux/errno.h>
+#include <linux/export.h>
 #include <linux/types.h>
 #include <linux/file.h>
 #include <linux/fs.h>
+#include <linux/init.h>
 #include <linux/mm.h>
+#include <linux/preempt.h>
 #include <linux/printk.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-- 
1.7.12.4