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<ha...@linux.vnet.ibm.com> --- 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,