From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758147Ab3FTQTW (ORCPT ); Thu, 20 Jun 2013 12:19:22 -0400 Received: from terminus.zytor.com ([198.137.202.10]:48286 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758092Ab3FTQTP (ORCPT ); Thu, 20 Jun 2013 12:19:15 -0400 Date: Thu, 20 Jun 2013 09:18:55 -0700 From: tip-bot for Oleg Nesterov Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, fweisbec@gmail.com, vincent.weaver@maine.edu, oleg@redhat.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, vincent.weaver@maine.edu, fweisbec@gmail.com, tglx@linutronix.de, oleg@redhat.com In-Reply-To: <20130620155011.GA6330@redhat.com> References: <20130620155011.GA6330@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] hw_breakpoint: Simplify list/ idx mess in toggle_bp_slot() paths Git-Commit-ID: e1ebe86203e6532eb5a0ae8f26ccae47aca548ae X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Thu, 20 Jun 2013 09:19:01 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: e1ebe86203e6532eb5a0ae8f26ccae47aca548ae Gitweb: http://git.kernel.org/tip/e1ebe86203e6532eb5a0ae8f26ccae47aca548ae Author: Oleg Nesterov AuthorDate: Thu, 20 Jun 2013 17:50:11 +0200 Committer: Ingo Molnar CommitDate: Thu, 20 Jun 2013 17:58:55 +0200 hw_breakpoint: Simplify list/idx mess in toggle_bp_slot() paths The enable/disable logic in toggle_bp_slot() is not symmetrical and imho very confusing. "old_count" in toggle_bp_task_slot() is actually new_count because this bp was already removed from the list. Change toggle_bp_slot() to always call list_add/list_del after toggle_bp_task_slot(). This way old_idx is task_bp_pinned() and this entry should be decremented, new_idx is +/-weight and we need to increment this element. The code/logic looks obvious. Reported-by: Vince Weaver Signed-off-by: Oleg Nesterov Acked-by: Frederic Weisbecker Link: http://lkml.kernel.org/r/20130620155011.GA6330@redhat.com Signed-off-by: Ingo Molnar --- kernel/events/hw_breakpoint.c | 40 ++++++++++++++++------------------------ 1 file changed, 16 insertions(+), 24 deletions(-) diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index ef8ebe5..dee0148 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -185,26 +185,20 @@ fetch_this_slot(struct bp_busy_slots *slots, int weight) static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable, enum bp_type_idx type, int weight) { - unsigned int *tsk_pinned; - int old_count = 0; - int old_idx = 0; - int idx = 0; - - old_count = task_bp_pinned(cpu, bp, type); - old_idx = old_count - 1; - idx = old_idx + weight; - - /* tsk_pinned[n] is the number of tasks having n breakpoints */ - tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); - if (enable) { - tsk_pinned[idx]++; - if (old_count > 0) - tsk_pinned[old_idx]--; - } else { - tsk_pinned[idx]--; - if (old_count > 0) - tsk_pinned[old_idx]++; - } + /* tsk_pinned[n-1] is the number of tasks having n>0 breakpoints */ + unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); + int old_idx, new_idx; + + old_idx = task_bp_pinned(cpu, bp, type) - 1; + if (enable) + new_idx = old_idx + weight; + else + new_idx = old_idx - weight; + + if (old_idx >= 0) + tsk_pinned[old_idx]--; + if (new_idx >= 0) + tsk_pinned[new_idx]++; } /* @@ -228,10 +222,6 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, } /* Pinned counter task profiling */ - - if (!enable) - list_del(&bp->hw.bp_list); - if (cpu >= 0) { toggle_bp_task_slot(bp, cpu, enable, type, weight); } else { @@ -241,6 +231,8 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, if (enable) list_add_tail(&bp->hw.bp_list, &bp_task_head); + else + list_del(&bp->hw.bp_list); } /*