linux-kernel - Re: [PATCH 1/1] PATCH: KGDB/KDB Fix no KDB config problem.

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Message-ID: <20131003165122.GB32755@gmail.com>
Date:	Thu, 3 Oct 2013 18:51:22 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Mike Travis <travis@....com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dimitri Sivanich <sivanich@....com>,
	Hedi Berriche <hedi@....com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] PATCH: KGDB/KDB Fix no KDB config problem.


* Mike Travis <travis@....com> wrote:

> Some code added to the debug_core module had KDB dependencies
> that it shouldn't have.
> 
> Signed-off-by: Mike Travis <travis@....com>
> ---
>  kernel/debug/debug_core.c |    8 ++++----
>  kernel/debug/debug_core.h |    2 ++
>  2 files changed, 6 insertions(+), 4 deletions(-)
> 
> --- linux.orig/kernel/debug/debug_core.c
> +++ linux/kernel/debug/debug_core.c
> @@ -575,8 +575,8 @@ return_normal:
>  		raw_spin_lock(&dbg_slave_lock);
>  
>  #ifdef CONFIG_SMP
> -	/* If SYSTEM_NMI, slaves are already waiting */
> -	if (ks->err_code == KDB_REASON_SYSTEM_NMI)
> +	/* If send_ready set, slaves are already waiting */
> +	if (ks->send_ready)
>  		atomic_set(ks->send_ready, 1);
>  
>  	/* Signal the other CPUs to enter kgdb_wait() */
> @@ -682,11 +682,11 @@ kgdb_handle_exception(int evector, int s
>  	if (arch_kgdb_ops.enable_nmi)
>  		arch_kgdb_ops.enable_nmi(0);
>  
> +	memset(ks, 0, sizeof(struct kgdb_state));
>  	ks->cpu			= raw_smp_processor_id();
>  	ks->ex_vector		= evector;
>  	ks->signo		= signo;
>  	ks->err_code		= ecode;
> -	ks->kgdb_usethreadid	= 0;
>  	ks->linux_regs		= regs;
>  
>  	if (kgdb_reenter_check(ks))
> @@ -750,7 +750,7 @@ int kgdb_nmicallin(int cpu, int trapnr,
>  		ks->cpu			= cpu;
>  		ks->ex_vector		= trapnr;
>  		ks->signo		= SIGTRAP;
> -		ks->err_code		= KDB_REASON_SYSTEM_NMI;
> +		ks->err_code		= KGDB_KDB_REASON_SYSTEM_NMI;
>  		ks->linux_regs		= regs;
>  		ks->send_ready		= send_ready;
>  		kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
> --- linux.orig/kernel/debug/debug_core.h
> +++ linux/kernel/debug/debug_core.h
> @@ -75,11 +75,13 @@ extern int kdb_stub(struct kgdb_state *k
>  extern int kdb_parse(const char *cmdstr);
>  extern int kdb_common_init_state(struct kgdb_state *ks);
>  extern int kdb_common_deinit_state(void);
> +#define KGDB_KDB_REASON_SYSTEM_NMI KDB_REASON_SYSTEM_NMI
>  #else /* ! CONFIG_KGDB_KDB */
>  static inline int kdb_stub(struct kgdb_state *ks)
>  {
>  	return DBG_PASS_EVENT;
>  }
> +#define KGDB_KDB_REASON_SYSTEM_NMI 0
>  #endif /* CONFIG_KGDB_KDB */
>  
>  #endif /* _DEBUG_CORE_H_ */

Hm, the KGDB_KDB_REASON_SYSTEM_NMI definition is a bit ugly. I still think 
there are layering violations here and just kludging it around doesn't 
solve it - a helper function that keeps kgdb details to the kgdb code 
would.

Anyway, if Jason is fine with this solution and upholds his Acked-by then 
I'll merge this into the first patch and apply the two patches.

Thanks,

	Ingo
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