From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:36540) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RETTF-0005rD-MH for qemu-devel@nongnu.org; Thu, 13 Oct 2011 18:09:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RETTB-0001Gw-H2 for qemu-devel@nongnu.org; Thu, 13 Oct 2011 18:09:45 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:59849) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RETTA-0001Eq-Tp for qemu-devel@nongnu.org; Thu, 13 Oct 2011 18:09:41 -0400 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.31.245]) by e23smtp04.au.ibm.com (8.14.4/8.13.1) with ESMTP id p9DM2jFH014145 for ; Fri, 14 Oct 2011 09:02:45 +1100 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p9DM9PfT2281520 for ; Fri, 14 Oct 2011 09:09:31 +1100 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p9DM9OOD012060 for ; Fri, 14 Oct 2011 09:09:24 +1100 Message-ID: <4E976191.5020009@linux.vnet.ibm.com> Date: Fri, 14 Oct 2011 03:39:21 +0530 From: Harsh Bora MIME-Version: 1.0 References: <1318538102-6982-1-git-send-email-harsh@linux.vnet.ibm.com> <1318538102-6982-2-git-send-email-harsh@linux.vnet.ibm.com> In-Reply-To: <1318538102-6982-2-git-send-email-harsh@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 2/2] Replace rwlocks with RCU variants of interfaces. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Harsh Prateek Bora Cc: pbonzini@redhat.com, jan.kiszka@web.de, qemu-devel@nongnu.org, aneesh.kumar@linux.vnet.ibm.com On 10/14/2011 02:05 AM, Harsh Prateek Bora wrote: > Use QLIST_INSERT_HEAD_RCU and rcu_read_lock/unlock instead of rwlocks. > Use v9fs_synth_mutex as a write-only mutex to handle concurrent writers. This patch is based on top of: http://repo.or.cz/w/qemu/v9fs.git/commitdiff/d647a2337e6e010c9f733d1ff68f7f97b27c5f80 > > Signed-off-by: Harsh Prateek Bora > --- > hw/9pfs/virtio-9p-synth.c | 26 ++++++++++++-------------- > 1 files changed, 12 insertions(+), 14 deletions(-) > > diff --git a/hw/9pfs/virtio-9p-synth.c b/hw/9pfs/virtio-9p-synth.c > index cbf74e4..567611e 100644 > --- a/hw/9pfs/virtio-9p-synth.c > +++ b/hw/9pfs/virtio-9p-synth.c > @@ -30,8 +30,7 @@ V9fsSynthNode v9fs_synth_root = { > .attr =&v9fs_synth_root.actual_attr, > }; > > -/*FIXME!! should be converted to qemu_rwlock_t */ > -static pthread_rwlock_t v9fs_synth_mutex; > +static QemuMutex v9fs_synth_mutex; > static int v9fs_synth_node_count; > /* set to 1 when the synth fs is ready */ > static int v9fs_synth_fs; > @@ -79,7 +78,7 @@ int qemu_v9fs_synth_mkdir(V9fsSynthNode *parent, int mode, > if (!parent) { > parent =&v9fs_synth_root; > } > - pthread_rwlock_wrlock(&v9fs_synth_mutex); > + qemu_mutex_lock(&v9fs_synth_mutex); > QLIST_FOREACH(tmp,&parent->child, sibling) { > if (!strcmp(tmp->name, name)) { > ret = EEXIST; > @@ -95,7 +94,7 @@ int qemu_v9fs_synth_mkdir(V9fsSynthNode *parent, int mode, > *result = node; > ret = 0; > err_out: > - pthread_rwlock_unlock(&v9fs_synth_mutex); > + qemu_mutex_unlock(&v9fs_synth_mutex); > return ret; > } > > @@ -116,7 +115,7 @@ int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode, > parent =&v9fs_synth_root; > } > > - pthread_rwlock_wrlock(&v9fs_synth_mutex); > + qemu_mutex_lock(&v9fs_synth_mutex); > QLIST_FOREACH(tmp,&parent->child, sibling) { > if (!strcmp(tmp->name, name)) { > ret = EEXIST; > @@ -134,10 +133,10 @@ int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode, > node->attr->mode = mode; > node->private = arg; > strncpy(node->name, name, sizeof(node->name)); > - QLIST_INSERT_HEAD(&parent->child, node, sibling); > + QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling); > ret = 0; > err_out: > - pthread_rwlock_unlock(&v9fs_synth_mutex); > + qemu_mutex_unlock(&v9fs_synth_mutex); > return ret; > } > > @@ -230,7 +229,7 @@ static int v9fs_synth_get_dentry(V9fsSynthNode *dir, struct dirent *entry, > int i = 0; > V9fsSynthNode *node; > > - pthread_rwlock_rdlock(&v9fs_synth_mutex); > + rcu_read_lock(); > QLIST_FOREACH(node,&dir->child, sibling) { > /* This is the off child of the directory */ > if (i == off) { > @@ -238,7 +237,7 @@ static int v9fs_synth_get_dentry(V9fsSynthNode *dir, struct dirent *entry, > } > i++; > } > - pthread_rwlock_unlock(&v9fs_synth_mutex); > + rcu_read_unlock(); > if (!node) { > /* end of directory */ > *result = NULL; > @@ -483,13 +482,14 @@ static int v9fs_synth_name_to_path(FsContext *ctx, V9fsPath *dir_path, > goto out; > } > /* search for the name in the childern */ > - pthread_rwlock_rdlock(&v9fs_synth_mutex); > + rcu_read_lock(); > QLIST_FOREACH(node,&dir_node->child, sibling) { > if (!strcmp(node->name, name)) { > break; > } > } > - pthread_rwlock_unlock(&v9fs_synth_mutex); > + rcu_read_unlock(); > + > if (!node) { > errno = ENOENT; > return -1; > @@ -532,11 +532,9 @@ static ssize_t my_test_read(void *in_buf, int len, off_t offset, void *arg) > static int v9fs_synth_init(FsContext *ctx) > { > V9fsSynthNode *node; > - pthread_rwlockattr_t rwlockattr; > > QLIST_INIT(&v9fs_synth_root.child); > - pthread_rwlockattr_init(&rwlockattr); > - pthread_rwlock_init(&v9fs_synth_mutex,&rwlockattr); > + qemu_mutex_init(&v9fs_synth_mutex); > > /* Add "." and ".." entries for root */ > v9fs_add_dir_node(&v9fs_synth_root, v9fs_synth_root.attr->mode,