Commit 2583e443 authored by Harsh Prateek Bora's avatar Harsh Prateek Bora Committed by Aneesh Kumar K.V
Browse files

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: default avatarHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
parent 5f7d05ec

hw/9pfs/virtio-9p-synth.c

+13 −16
Original line number Diff line number Diff line
@@ -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,