From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753543AbdK2IjO (ORCPT ); Wed, 29 Nov 2017 03:39:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49260 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753417AbdK2IjL (ORCPT ); Wed, 29 Nov 2017 03:39:11 -0500 From: Jiri Olsa To: Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo Cc: lkml , Namhyung Kim , David Ahern , Andi Kleen , Milind Chabbi , Alexander Shishkin , Michael Ellerman , Hari Bathini , Jin Yao , Kan Liang , Sukadev Bhattiprolu , Oleg Nesterov , Will Deacon Subject: [PATCH 3/8] hw_breakpoint: Add modify_bp_slot function Date: Wed, 29 Nov 2017 09:38:48 +0100 Message-Id: <20171129083853.28022-4-jolsa@kernel.org> In-Reply-To: <20171129083853.28022-1-jolsa@kernel.org> References: <20171129083853.28022-1-jolsa@kernel.org> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 29 Nov 2017 08:39:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Adding modify_bp_slot function to keep slot numbers correct when changing the breakpoint type. Using existing __release_bp_slot/__reserve_bp_slot call sequence to update the slot counts. Signed-off-by: Jiri Olsa --- kernel/events/hw_breakpoint.c | 46 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 39 insertions(+), 7 deletions(-) diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 9b31fbcc3305..776948beb4ac 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -44,6 +44,7 @@ #include #include #include +#include #include /* @@ -344,6 +345,38 @@ void release_bp_slot(struct perf_event *bp) mutex_unlock(&nr_bp_mutex); } +static int __modify_bp_slot(struct perf_event *bp, u64 old_type) +{ + int err; + + __release_bp_slot(bp, old_type); + + err = __reserve_bp_slot(bp, bp->attr.bp_type); + if (err) { + /* + * Reserve the old_type slot back in case + * there's no space for the new type. + * + * This must succeed, because we just released + * the old_type slot in the __release_bp_slot + * call above. If not, something is broken. + */ + WARN_ON(__reserve_bp_slot(bp, old_type)); + } + + return err; +} + +static int modify_bp_slot(struct perf_event *bp, u64 old_type) +{ + int ret; + + mutex_lock(&nr_bp_mutex); + ret = __modify_bp_slot(bp, old_type); + mutex_unlock(&nr_bp_mutex); + return ret; +} + /* * Allow the kernel debugger to reserve breakpoint slots without * taking a lock using the dbg_* variant of for the reserve and @@ -435,6 +468,7 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att u64 old_addr = bp->attr.bp_addr; u64 old_len = bp->attr.bp_len; int old_type = bp->attr.bp_type; + bool modify = attr->bp_type != old_type; int err = 0; /* @@ -452,12 +486,9 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att bp->attr.bp_type = attr->bp_type; bp->attr.bp_len = attr->bp_len; - if (attr->disabled) - goto end; - err = validate_hw_breakpoint(bp); - if (!err) - perf_event_enable(bp); + if (!err && modify) + err = modify_bp_slot(bp, old_type); if (err) { bp->attr.bp_addr = old_addr; @@ -469,9 +500,10 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att return err; } -end: - bp->attr.disabled = attr->disabled; + if (!attr->disabled) + perf_event_enable(bp); + bp->attr.disabled = attr->disabled; return 0; } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); -- 2.13.6