Use vfs functions to allocate/free the resources used for a socket (Part I)

This part changes LWIP so that it lets vfs to free the resources
used to integrate sockets in vfs.

Right now sock_net_close frees the vfscore_file, dentry and vnode
used for the socket. This can cause problems since vfs unlocks the
vnode after calling sock_net_close so it accesses freed memory.

We will let vfs handle the freeing of the resources used for a
socket by setting the dentry refcount to 1 such that, when a socket is
closed (so its vfscore_file is also closed), the dentry's refcount
hits 0, the dentry is deleted so the vnode refcount hits 0
and it is also deleted.

Signed-off-by: Mihai Pogonaru <pogonarumihai@gmail.com>
Reviewed-by: Costin Lupu <costin.lupu@cs.pub.ro>

diff --git a/sockets.c b/sockets.c
index e95758d83e8b55c38bbfc080d52272431cb3525b..cbe3030812cf3d3526a23a6c1363bab73f4f1a49 100644 (file)
--- a/sockets.c
+++ b/sockets.c
@@ -37,6 +37,7 @@
 #include <sys/time.h>
 #include <vfscore/file.h>
 #include <vfscore/fs.h>
+#include <vfscore/mount.h>
 #include <vfscore/vnode.h>
 #include <uk/alloc.h>
 #include <uk/essentials.h>
@@ -48,8 +49,16 @@
 #define SOCK_NET_SET_ERRNO(errcode) \
        (errno = -(errcode))
 
+/*
+ * Bogus mount point used by all sockets
+ *
+ * We need this because when deleting a vnode
+ * vfs calls vfs_unbusy on its mount point
+ */
+static struct mount s_mount;
+
 struct sock_net_file {
-       struct vfscore_file vfscore_file;
+       struct vfscore_file *vfscore_file;
        int sock_fd;
 };
 
@@ -58,7 +67,7 @@ static inline struct sock_net_file *sock_net_file_get(int fd)
        struct sock_net_file *file = NULL;
        struct vfscore_file *fos;
 
-       fos  = vfscore_get_file(fd);
+       fos = vfscore_get_file(fd);
        if (!fos) {
                LWIP_DEBUGF(SOCKETS_DEBUG,
                            ("failed with invalid descriptor\n"));
@@ -71,7 +80,7 @@ static inline struct sock_net_file *sock_net_file_get(int fd)
                file = ERR2PTR(-EBADF);
                goto EXIT;
        }
-       file = __containerof(fos, struct sock_net_file, vfscore_file);
+       file = fos->f_data;
 EXIT:
        return file;
 }
@@ -81,6 +90,7 @@ static int sock_fd_alloc(struct vnops *v_op, int sock_fd)
        int ret = 0;
        int vfs_fd;
        struct sock_net_file *file = NULL;
+       struct vfscore_file *vfs_file = NULL;
        struct dentry *s_dentry;
        struct vnode *s_vnode;
 
@@ -101,6 +111,13 @@ static int sock_fd_alloc(struct vnops *v_op, int sock_fd)
                            ("Failed to allocate socket file: Out of memory\n"));
                goto ERR_MALLOC_FILE;
        }
+       vfs_file = uk_calloc(uk_alloc_get_default(), 1, sizeof(*vfs_file));
+       if (!vfs_file) {
+               ret = -ENOMEM;
+               LWIP_DEBUGF(SOCKETS_DEBUG,
+                               ("Failed to allocate socket vfs_file: Out of memory\n"));
+               goto ERR_MALLOC_VFS_FILE;
+       }
        s_dentry = uk_calloc(uk_alloc_get_default(), 1, sizeof(*s_dentry));
        if (!s_dentry) {
                ret = -ENOMEM;
@@ -117,26 +134,46 @@ static int sock_fd_alloc(struct vnops *v_op, int sock_fd)
        }
 
        /* Put things together, and fill out necessary fields */
-       file->vfscore_file.fd = vfs_fd;
-       file->vfscore_file.f_flags = UK_FWRITE | UK_FREAD;
-       file->vfscore_file.f_count = 1;
-       file->vfscore_file.f_dentry = s_dentry;
+       vfs_file->fd = vfs_fd;
+       vfs_file->f_flags = UK_FWRITE | UK_FREAD;
+       vfs_file->f_count = 1;
+       vfs_file->f_data = file;
+       vfs_file->f_dentry = s_dentry;
 
+       s_dentry->d_refcnt = 1;
        s_dentry->d_vnode = s_vnode;
 
+       /*
+        * Provide bogus but valid addresses to allow
+        * vfs to remove nodes from lists
+        */
+       s_dentry->d_link.pprev = &s_dentry->d_link.next;
+       s_dentry->d_names_link.next = &s_dentry->d_names_link;
+       s_dentry->d_names_link.prev = &s_dentry->d_names_link;
+
        s_vnode->v_op = v_op;
        uk_mutex_init(&s_vnode->v_lock);
        s_vnode->v_refcnt = 1;
        s_vnode->v_data = file;
        s_vnode->v_type = VSOCK;
+       s_vnode->v_mount = &s_mount;
+       s_mount.m_count++;
 
+       /*
+        * Provide bogus but valid addresses to allow
+        * vfs to remove nodes from lists
+        */
+       s_vnode->v_link.next = &s_vnode->v_link;
+       s_vnode->v_link.prev = &s_vnode->v_link;
+
+       file->vfscore_file = vfs_file;
        file->sock_fd = sock_fd;
        LWIP_DEBUGF(SOCKETS_DEBUG, ("Allocated socket %d (%x)\n",
-                                   file->vfscore_file.fd,
+                                   file->vfscore_file->fd,
                                    file->sock_fd));
 
        /* Storing the information within the vfs structure */
-       ret = vfscore_install_fd(vfs_fd, &file->vfscore_file);
+       ret = vfscore_install_fd(vfs_fd, file->vfscore_file);
        if (ret) {
                LWIP_DEBUGF(SOCKETS_DEBUG,
                            ("Failed to install socket fd\n"));
@@ -151,6 +188,8 @@ ERR_VFS_INSTALL:
 ERR_MALLOC_VNODE:
        uk_free(uk_alloc_get_default(), s_dentry);
 ERR_MALLOC_DENTRY:
+       uk_free(uk_alloc_get_default(), vfs_file);
+ERR_MALLOC_VFS_FILE:
        uk_free(uk_alloc_get_default(), file);
 ERR_MALLOC_FILE:
        vfscore_put_fd(vfs_fd);
@@ -160,15 +199,15 @@ ERR_EXIT:
 }
 
 static int sock_net_close(struct vnode *s_vnode,
-                         struct vfscore_file *vfscore_file __maybe_unused)
+                         struct vfscore_file *vfscore_file)
 {
-       int ret = 0;
+       int ret;
        struct sock_net_file *file = NULL;
 
        file = s_vnode->v_data;
        LWIP_DEBUGF(SOCKETS_DEBUG, ("%s fd:%d lwip_fd:%d\n",
                                    __func__,
-                                   file->vfscore_file.fd,
+                                   file->vfscore_file->fd,
                                    file->sock_fd));
 
        UK_ASSERT(vfscore_file->f_dentry->d_vnode == s_vnode);
@@ -176,12 +215,13 @@ static int sock_net_close(struct vnode *s_vnode,
 
        /* Close and release the lwip socket */
        ret = lwip_close(file->sock_fd);
-       /* Free socket vnode */
-       uk_free(uk_alloc_get_default(), file->vfscore_file.f_dentry->d_vnode);
-       /* Free socket dentry */
-       uk_free(uk_alloc_get_default(), file->vfscore_file.f_dentry);
-       /* Free socket file */
+
+       /*
+        * Free socket file
+        * The rest of the resources will be freed by vfs
+        */
        uk_free(uk_alloc_get_default(), file);
+
        return ret;
 }
 
@@ -194,7 +234,7 @@ static ssize_t sock_net_write(struct vnode *s_vnode,
        file = s_vnode->v_data;
        LWIP_DEBUGF(SOCKETS_DEBUG, ("%s fd:%d lwip_fd:%d\n",
                                    __func__,
-                                   file->vfscore_file.fd,
+                                   file->vfscore_file->fd,
                                    file->sock_fd));
        ret = lwip_writev(file->sock_fd, buf->uio_iov, buf->uio_iovcnt);
        return ret;
@@ -210,16 +250,19 @@ static ssize_t sock_net_read(struct vnode *s_vnode,
        file = s_vnode->v_data;
        LWIP_DEBUGF(SOCKETS_DEBUG, ("%s fd:%d lwip_fd:%d\n",
                                    __func__,
-                                   file->vfscore_file.fd,
+                                   file->vfscore_file->fd,
                                    file->sock_fd));
        ret = lwip_readv(file->sock_fd, buf->uio_iov, buf->uio_iovcnt);
        return ret;
 }
 
+#define sock_net_inactive  ((vnop_inactive_t) vfscore_vop_nullop)
+
 static struct vnops sock_net_fops = {
        .vop_close = sock_net_close,
        .vop_write = sock_net_write,
        .vop_read  = sock_net_read,
+       .vop_inactive = sock_net_inactive
 };
 
 int socket(int domain, int type, int protocol)
@@ -296,7 +339,7 @@ int accept(int s, struct sockaddr *addr, socklen_t *addrlen)
        }
        ret = vfs_fd;
 EXIT_FDROP:
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 
@@ -328,7 +371,7 @@ int bind(int s, const struct sockaddr *name, socklen_t namelen)
                goto EXIT_FDROP;
        }
 EXIT_FDROP:
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -355,7 +398,7 @@ int poll(struct pollfd fds[], nfds_t nfds, int timeout)
                        }
                        lwip_fds[i].fd = file->sock_fd;
                        lwip_fds[i].events = fds[i].events;
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
        }
 
@@ -408,7 +451,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                        if (maxfd < file->sock_fd)
                                maxfd = file->sock_fd;
                        FD_SET(file->sock_fd, &rd);
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
                if (writefds && FD_ISSET(i, writefds)) {
                        file = sock_net_file_get(i);
@@ -423,7 +466,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                        if (maxfd < file->sock_fd)
                                maxfd = file->sock_fd;
                        FD_SET(file->sock_fd, &wr);
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
                if (exceptfds && FD_ISSET(i, exceptfds)) {
                        file = sock_net_file_get(i);
@@ -438,7 +481,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                        if (maxfd < file->sock_fd)
                                maxfd = file->sock_fd;
                        FD_SET(file->sock_fd, &xc);
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
        }
 
@@ -459,7 +502,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                        file = sock_net_file_get(i);
                        if (!FD_ISSET(file->sock_fd, &rd))
                                FD_CLR(i, readfds);
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
                if (writefds && FD_ISSET(i, writefds)) {
                        /* This lookup can't fail, or it would already have
@@ -468,7 +511,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                        file = sock_net_file_get(i);
                        if (!FD_ISSET(file->sock_fd, &wr))
                                FD_CLR(i, writefds);
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
                if (exceptfds && FD_ISSET(i, exceptfds)) {
                        /* This lookup can't fail, or it would already have
@@ -477,7 +520,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                        file = sock_net_file_get(i);
                        if (!FD_ISSET(file->sock_fd, &xc))
                                FD_CLR(i, exceptfds);
-                       vfscore_put_file(&file->vfscore_file); /* release refcount */
+                       vfscore_put_file(file->vfscore_file); /* release refcount */
                }
        }
 
@@ -501,7 +544,7 @@ int shutdown(int s, int how)
        }
        /* Shutdown of the descriptor */
        ret = lwip_shutdown(file->sock_fd, how);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -519,7 +562,7 @@ int getpeername(int s, struct sockaddr *name, socklen_t *namelen)
                goto EXIT;
        }
        ret = lwip_getpeername(file->sock_fd, name, namelen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -537,7 +580,7 @@ int getsockname(int s, struct sockaddr *name, socklen_t *namelen)
                goto EXIT;
        }
        ret = lwip_getsockname(file->sock_fd, name, namelen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -556,7 +599,7 @@ int getsockopt(int s, int level, int optname, void *optval, socklen_t *optlen)
                goto EXIT;
        }
        ret = lwip_getsockopt(file->sock_fd, level, optname, optval, optlen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -576,7 +619,7 @@ int setsockopt(int s, int level, int optname, const void *optval,
                goto EXIT;
        }
        ret = lwip_setsockopt(file->sock_fd, level, optname, optval, optlen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -595,7 +638,7 @@ int connect(int s, const struct sockaddr *name, socklen_t namelen)
                goto EXIT;
        }
        ret = lwip_connect(file->sock_fd, name, namelen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -614,7 +657,7 @@ int listen(int s, int backlog)
                goto EXIT;
        }
        ret = lwip_listen(file->sock_fd, backlog);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -633,7 +676,7 @@ int recv(int s, void *mem, size_t len, int flags)
                goto EXIT;
        }
        ret = lwip_recv(file->sock_fd, mem, len, flags);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -653,7 +696,7 @@ int recvfrom(int s, void *mem, size_t len, int flags,
                goto EXIT;
        }
        ret = lwip_recvfrom(file->sock_fd, mem, len, flags, from, fromlen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -672,7 +715,7 @@ int send(int s, const void *dataptr, size_t size, int flags)
                goto EXIT;
        }
        ret = lwip_send(file->sock_fd, dataptr, size, flags);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -691,7 +734,7 @@ int sendmsg(int s, const struct msghdr *message, int flags)
                goto EXIT;
        }
        ret = lwip_sendmsg(file->sock_fd, message, flags);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }
@@ -711,7 +754,7 @@ int sendto(int s, const void *dataptr, size_t size, int flags,
                goto EXIT;
        }
        ret = lwip_sendto(file->sock_fd, dataptr, size, flags, to, tolen);
-       vfscore_put_file(&file->vfscore_file); /* release refcount */
+       vfscore_put_file(file->vfscore_file); /* release refcount */
 EXIT:
        return ret;
 }