[PATCH] misc/coverity: Model __builtin_unreachable()

[PATCH] misc/coverity: Model __builtin_unreachable()

[Andrew Cooper]

This resolves 23 issues Coverity had identified by following the false path of
an ASSERT().

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: coverity@xenproject.org
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>
CC: Tim Deegan <tim@xen.org>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
---
 misc/coverity/model.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/misc/coverity/model.c b/misc/coverity/model.c
index fac2ecb..bd62566 100644
--- a/misc/coverity/model.c
+++ b/misc/coverity/model.c
@@ -121,6 +121,16 @@ void libxl__ctx_unlock(libxl_ctx *ctx)
 }
 
 /*
+ * Coverity doesn't understand __builtin_unreachable(), which causes it to
+ * incorrectly find issues based on continuing execution along the false
+ * branch of an ASSERT().
+ */
+void __builtin_unreachable(void)
+{
+    __coverity_panic__();
+}
+
+/*
  * Local variables:
  * mode: C
  * c-file-style: "BSD"
-- 
1.7.10.4

Re: [PATCH] misc/coverity: Model __builtin_unreachable()

[Jan Beulich]

>>> On 24.09.14 at 15:53, <andrew.cooper3@citrix.com> wrote:
>  /*
> + * Coverity doesn't understand __builtin_unreachable(), which causes it to
> + * incorrectly find issues based on continuing execution along the false
> + * branch of an ASSERT().
> + */
> +void __builtin_unreachable(void)
> +{
> +    __coverity_panic__();
> +}

And (for those of us without intimate knowledge of Coverity)
__coverity_panic__() does what? By its name I would conclude
it terminates the current scan altogether...

Jan

Re: [PATCH] misc/coverity: Model __builtin_unreachable()

[Andrew Cooper]

On 24/09/14 15:50, Jan Beulich wrote:
>>>> On 24.09.14 at 15:53, <andrew.cooper3@citrix.com> wrote:
>>  /*
>> + * Coverity doesn't understand __builtin_unreachable(), which causes it to
>> + * incorrectly find issues based on continuing execution along the false
>> + * branch of an ASSERT().
>> + */
>> +void __builtin_unreachable(void)
>> +{
>> +    __coverity_panic__();
>> +}
> And (for those of us without intimate knowledge of Coverity)
> __coverity_panic__() does what? By its name I would conclude
> it terminates the current scan altogether...
>
> Jan
>

__coverity_panic__() is a coverity modelling function defined as "ending
the current execution path".  (See https://scan.coverity.com/tune which
might be behind a login)

Its naming is somewhat unfortunate.

~Andrew