From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philippe Gerum In-Reply-To: <470E1FD6.2030607@domain.hid> References: <470E1FD6.2030607@domain.hid> Content-Type: text/plain Date: Mon, 15 Oct 2007 19:29:32 +0200 Message-Id: <1192469372.6001.20.camel@domain.hid> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: Philippe Gerum Subject: Re: [Adeos-main] [PATCH 1/4] tracer: cleanup critical paths Reply-To: rpm@xenomai.org List-Id: General discussion about Adeos List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: adeos-main@gna.org On Thu, 2007-10-11 at 15:06 +0200, Jan Kiszka wrote: > for_each_online_cpu is not free of function calls on SMP, thus causes > false NMI noise in the tracer log (due to tracer recursions). Switch to > some plain loop instead. This one breaks badly on SMP, where NR_CPUS is likely greater than the highest numbered CPU from the possible CPU map (at least if you don't lower the former value at config time), so in the TRACE_VMALLOC case, you end up dereferencing NULL trace_paths[] pointers. Since we may not want to mark __next_cpu() and find_next_bit() as notrace routines, we have to check the boundaries: diff --git a/kernel/ipipe/tracer.c b/kernel/ipipe/tracer.c index 2326706..8ecbe1a 100644 --- a/kernel/ipipe/tracer.c +++ b/kernel/ipipe/tracer.c @@ -255,7 +255,7 @@ __ipipe_trace_freeze(int cpu_id, struct ipipe_trace_path *tp, int pos) active = __ipipe_get_free_trace_path(active, cpu_id); /* check if this is the first frozen path */ - for (i = 0; i < NR_CPUS; i++) { + for (i = 0; i < NR_CPUS && trace_paths[i] != NULL; i++) { if ((i != cpu_id) && (trace_paths[i][frozen_path[i]].end >= 0)) tp->end = -1; @@ -520,7 +520,7 @@ int ipipe_trace_max_reset(void) flags = __ipipe_global_path_lock(); - for (cpu_id = 0; cpu_id < NR_CPUS; cpu_id++) { + for (cpu_id = 0; cpu_id < NR_CPUS && trace_paths[cpu_id] != NULL; cpu_id++) { path = &trace_paths[cpu_id][max_path[cpu_id]]; if (path->dump_lock) { -- Philippe.