Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754569Ab3JCRxc (ORCPT ); Thu, 3 Oct 2013 13:53:32 -0400 Received: from relay1.sgi.com ([192.48.179.29]:41460 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753893Ab3JCRxb (ORCPT ); Thu, 3 Oct 2013 13:53:31 -0400 Message-ID: <524DAF17.8040104@sgi.com> Date: Thu, 03 Oct 2013 10:53:27 -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> In-Reply-To: <20131003171520.GA5144@gmail.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: 3989 Lines: 115 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? -- 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/