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hw/9pfs: Replace rwlocks with RCU variants of interfaces. 

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 <harsh@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
This commit is contained in:
Harsh Prateek Bora 2011-10-14 02:05:02 +05:30 committed by Aneesh Kumar K.V
parent 5f7d05ecfd
commit 2583e44367
1 changed files with 13 additions and 16 deletions
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29
hw/9pfs/virtio-9p-synth.c
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@ -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;
@ -60,7 +59,7 @@ static V9fsSynthNode *v9fs_add_dir_node(V9fsSynthNode *parent, int mode,
}
node->private = node;
strncpy(node->name, name, sizeof(node->name));
QLIST_INSERT_HEAD(&parent->child, node, sibling);
QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling);
return node;
}
@ -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;
@ -519,11 +519,8 @@ static int v9fs_synth_unlinkat(FsContext *ctx, V9fsPath *dir,
static int v9fs_synth_init(FsContext *ctx)
{
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,