From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52616) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHD4e-00038U-FK for qemu-devel@nongnu.org; Fri, 30 Jan 2015 10:01:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YHD4d-0005aC-KM for qemu-devel@nongnu.org; Fri, 30 Jan 2015 10:01:32 -0500 Received: from mail-wi0-x233.google.com ([2a00:1450:400c:c05::233]:41881) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHD4d-0005a2-Cl for qemu-devel@nongnu.org; Fri, 30 Jan 2015 10:01:31 -0500 Received: by mail-wi0-f179.google.com with SMTP id l15so3185513wiw.0 for ; Fri, 30 Jan 2015 07:01:30 -0800 (PST) Received: from playground.station (net-93-66-105-136.cust.vodafonedsl.it. [93.66.105.136]) by mx.google.com with ESMTPSA id q10sm15273370wjr.41.2015.01.30.07.01.29 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 30 Jan 2015 07:01:29 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Fri, 30 Jan 2015 16:01:10 +0100 Message-Id: <1422630078-18704-4-git-send-email-pbonzini@redhat.com> In-Reply-To: <1422630078-18704-1-git-send-email-pbonzini@redhat.com> References: <1422630078-18704-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 03/11] rcu: allow nesting of rcu_read_lock/rcu_read_unlock List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Reviewed-by: Fam Zheng Signed-off-by: Paolo Bonzini --- include/qemu/rcu.h | 15 ++++++++++++++- tests/rcutorture.c | 2 ++ 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h index cfef36e..da043f2 100644 --- a/include/qemu/rcu.h +++ b/include/qemu/rcu.h @@ -68,6 +68,9 @@ struct rcu_reader_data { unsigned long ctr; bool waiting; + /* Data used by reader only */ + unsigned depth; + /* Data used for registry, protected by rcu_gp_lock */ QLIST_ENTRY(rcu_reader_data) node; }; @@ -77,8 +80,13 @@ extern __thread struct rcu_reader_data rcu_reader; static inline void rcu_read_lock(void) { struct rcu_reader_data *p_rcu_reader = &rcu_reader; + unsigned ctr; + + if (p_rcu_reader->depth++ > 0) { + return; + } - unsigned ctr = atomic_read(&rcu_gp_ctr); + ctr = atomic_read(&rcu_gp_ctr); atomic_xchg(&p_rcu_reader->ctr, ctr); if (atomic_read(&p_rcu_reader->waiting)) { atomic_set(&p_rcu_reader->waiting, false); @@ -90,6 +98,11 @@ static inline void rcu_read_unlock(void) { struct rcu_reader_data *p_rcu_reader = &rcu_reader; + assert(p_rcu_reader->depth != 0); + if (--p_rcu_reader->depth > 0) { + return; + } + atomic_xchg(&p_rcu_reader->ctr, 0); if (atomic_read(&p_rcu_reader->waiting)) { atomic_set(&p_rcu_reader->waiting, false); diff --git a/tests/rcutorture.c b/tests/rcutorture.c index e370843..93ec1b3 100644 --- a/tests/rcutorture.c +++ b/tests/rcutorture.c @@ -255,9 +255,11 @@ static void *rcu_read_stress_test(void *arg) if (p->mbtest == 0) { n_mberror++; } + rcu_read_lock(); for (i = 0; i < 100; i++) { garbage++; } + rcu_read_unlock(); pc = p->pipe_count; rcu_read_unlock(); if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) { -- 1.8.3.1