linux-kernel - Re: [PATCH v2] nfs: remove incorrect fallthrough label

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Date:   Thu, 17 Sep 2020 18:36:01 -0700
From:   Joe Perches <joe@...ches.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        "Gustavo A . R . Silva" <gustavo@...eddedor.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Hongxiang Lou <louhongxiang@...wei.com>,
        Miaohe Lin <linmiaohe@...wei.com>, linux-nfs@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH v2] nfs: remove incorrect fallthrough label

On Thu, 2020-09-17 at 14:41 -0700, Nick Desaulniers wrote:
> On Wed, Sep 16, 2020 at 1:19 PM Joe Perches <joe@...ches.com> wrote:
> > On Wed, 2020-09-16 at 13:02 -0700, Nick Desaulniers wrote:
> > > * (call of function with __attribute__(__noreturn__))
> > 
> > I guess panic counts.  I count 11 of those.
> > 
> > Are there any other uses of functions with __noreturn
> > in switch/case label blocks?
> 
> If you look at global_noreturns in tools/objtool/check.c:
>  145   static const char * const global_noreturns[] = {
>  146     "__stack_chk_fail",
>  147     "panic",
>  148     "do_exit",
>  149     "do_task_dead",
>  150     "__module_put_and_exit",
>  151     "complete_and_exit",
>  152     "__reiserfs_panic",
>  153     "lbug_with_loc",
>  154     "fortify_panic",
>  155     "usercopy_abort",
>  156     "machine_real_restart",
>  157     "rewind_stack_do_exit",
>  158     "kunit_try_catch_throw",
>  159   };
> 
> Whether they occur or not at the position you ask; I haven't checked.

Just fyi:

Other than the 11 instances of panic, I found only a
single use of any other function above in a switch/case:

drivers/pnp/pnpbios/core.c:163:			complete_and_exit(&unload_sem, 0);
		case PNP_SYSTEM_NOT_DOCKED:

Found with:

$ grep-2.5.4 -rP --include=*.[ch] -n '\b(?:__stack_chk_fail|panic|do_exit|do_task_dead|__module_put_and_exit|complete_and_exit|__reiserfs_panic|lbug_with_loc|fortify_panic|usercopy_abort|machine_real_restart|rewind_stack_do_exit|kunit_try_catch_throw)\s*(?:\([^\)]*\))?\s*;\s*(case\s+\w+|default)\s*:' *