From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46721) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YEJ34-0005hs-Ta for qemu-devel@nongnu.org; Thu, 22 Jan 2015 09:47:59 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YEJ33-0001tl-WB for qemu-devel@nongnu.org; Thu, 22 Jan 2015 09:47:54 -0500 Received: from mail-wg0-x22c.google.com ([2a00:1450:400c:c00::22c]:33728) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YEJ33-0001sw-M5 for qemu-devel@nongnu.org; Thu, 22 Jan 2015 09:47:53 -0500 Received: by mail-wg0-f44.google.com with SMTP id z12so2163807wgg.3 for ; Thu, 22 Jan 2015 06:47:53 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Thu, 22 Jan 2015 15:47:21 +0100 Message-Id: <1421938053-10318-4-git-send-email-pbonzini@redhat.com> In-Reply-To: <1421938053-10318-1-git-send-email-pbonzini@redhat.com> References: <1421938053-10318-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 03/15] 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 Cc: borntraeger@de.ibm.com, famz@redhat.com, stefanha@redhat.com 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 214985f..31461c3 100644 --- a/tests/rcutorture.c +++ b/tests/rcutorture.c @@ -257,9 +257,11 @@ 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