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Re: [Qemu-devel] [PATCH v2 2/2] Replace rwlocks with RCU variants of int
From: |
Aneesh Kumar K.V |
Subject: |
Re: [Qemu-devel] [PATCH v2 2/2] Replace rwlocks with RCU variants of interfaces. |
Date: |
Fri, 14 Oct 2011 10:26:35 +0530 |
User-agent: |
Notmuch/0.9_rc1-42-g76fdca8 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
On Fri, 14 Oct 2011 02:05:02 +0530, Harsh Prateek Bora <address@hidden> 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.
>
> Signed-off-by: Harsh Prateek Bora <address@hidden>
> ---
> 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;
We sould be using QLIST_INSERT_HEAD_RCU even in v9fs_add_dir_node
> }
>
> @@ -116,7 +115,7 @@ int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int
> mode,
> parent = &v9fs_synth_root;
> }
>
-aneesh