Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754784Ab3JCR7E (ORCPT ); Thu, 3 Oct 2013 13:59:04 -0400 Received: from relay3.sgi.com ([192.48.152.1]:36689 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754249Ab3JCR7C (ORCPT ); Thu, 3 Oct 2013 13:59:02 -0400 Message-ID: <524DB05F.3030906@sgi.com> Date: Thu, 03 Oct 2013 10:58:55 -0700 From: Mike Travis User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: Ingo Molnar CC: Ingo Molnar , Jason Wessel , Peter Zijlstra , Paul Mackerras , Arnaldo Carvalho de Melo , "H. Peter Anvin" , Thomas Gleixner , Andrew Morton , Dimitri Sivanich , Hedi Berriche , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] PATCH: KGDB/KDB Fix no KDB config problem. References: <20131003163824.966169920@asylum.americas.sgi.com> <20131003163825.184494258@asylum.americas.sgi.com> <20131003165122.GB32755@gmail.com> <524DA381.2050108@sgi.com> <20131003171520.GA5144@gmail.com> <524DAF17.8040104@sgi.com> In-Reply-To: <524DAF17.8040104@sgi.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4235 Lines: 122 On 10/3/2013 10:53 AM, Mike Travis wrote: > > > On 10/3/2013 10:15 AM, Ingo Molnar wrote: >> >> * Mike Travis wrote: >> >>> >>> >>> On 10/3/2013 9:51 AM, Ingo Molnar wrote: >>>> >>>> * Mike Travis wrote: >>>> >>>>> Some code added to the debug_core module had KDB dependencies >>>>> that it shouldn't have. >>>>> >>>>> Signed-off-by: Mike Travis >>>>> --- >>>>> 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 >>>> >>> >>> Would you prefer a simple #ifdef CONFIG_KGDB_KDB around the assignment? >> >> An #ifdef doesn't solve the layering violation! >> >> kernel/debug/debug_core.c didn't have any serious use of #ifdef >> CONFIG_KGDB_KDB before (it used it to flavor a few printks) and I'm not >> convinced it needs one for this feature either. >> >> So if that whole chunk is kdb dependent, why not shuffle that into a >> nicely named function and host it somewhere appropriate in >> kernel/debug/kdb/? That function would turn into an empty inline function >> in the !CONFIG_KGDB_KDB case. >> >> But ... it's up to Jason really whether he wants to abstract that piece of >> code out, I'm just kibitzing here really. >> >> Thanks, >> >> Ingo >> > > If I moved it to KDB then we would lose the capability to enter KGDB > mode and the gdb_stub functionality. The #ifdef could have a comment > to this effect? > Another option would be to pass the code in as the caller knows if KDB is defined or not? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/