Author: Trond Myklebust SUNRPC: rpc_timeout_upcall_queue should not sleep The function rpc_timeout_upcall_queue runs from a workqueue, and hence sleeping is not recommended. Convert the protection of the upcall queue from being mutex-based to being spinlock-based. Signed-off-by: Trond Myklebust --- net/sunrpc/rpc_pipe.c | 96 ++++++++++++++++++++++++++++++------------------- 1 files changed, 58 insertions(+), 38 deletions(-) diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index 9764c80..7281746 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -38,44 +38,42 @@ static kmem_cache_t *rpc_inode_cachep __ #define RPC_UPCALL_TIMEOUT (30*HZ) -static void -__rpc_purge_list(struct rpc_inode *rpci, struct list_head *head, int err) +static void rpc_purge_list(struct rpc_inode *rpci, struct list_head *head, + void (*destroy_msg)(struct rpc_pipe_msg *), int err) { struct rpc_pipe_msg *msg; - void (*destroy_msg)(struct rpc_pipe_msg *); - destroy_msg = rpci->ops->destroy_msg; - while (!list_empty(head)) { + if (list_empty(head)) + return; + do { msg = list_entry(head->next, struct rpc_pipe_msg, list); - list_del_init(&msg->list); + list_del(&msg->list); msg->errno = err; destroy_msg(msg); - } -} - -static void -__rpc_purge_upcall(struct inode *inode, int err) -{ - struct rpc_inode *rpci = RPC_I(inode); - - __rpc_purge_list(rpci, &rpci->pipe, err); - rpci->pipelen = 0; + } while (!list_empty(head)); wake_up(&rpci->waitq); } static void rpc_timeout_upcall_queue(void *data) { + LIST_HEAD(free_list); struct rpc_inode *rpci = (struct rpc_inode *)data; struct inode *inode = &rpci->vfs_inode; + void (*destroy_msg)(struct rpc_pipe_msg *); - mutex_lock(&inode->i_mutex); - if (rpci->ops == NULL) - goto out; - if (rpci->nreaders == 0 && !list_empty(&rpci->pipe)) - __rpc_purge_upcall(inode, -ETIMEDOUT); -out: - mutex_unlock(&inode->i_mutex); + spin_lock(&inode->i_lock); + if (rpci->ops == NULL) { + spin_unlock(&inode->i_lock); + return; + } + destroy_msg = rpci->ops->destroy_msg; + if (rpci->nreaders == 0) { + list_splice_init(&rpci->pipe, &free_list); + rpci->pipelen = 0; + } + spin_unlock(&inode->i_lock); + rpc_purge_list(rpci, &free_list, destroy_msg, -ETIMEDOUT); } int @@ -84,7 +82,7 @@ rpc_queue_upcall(struct inode *inode, st struct rpc_inode *rpci = RPC_I(inode); int res = -EPIPE; - mutex_lock(&inode->i_mutex); + spin_lock(&inode->i_lock); if (rpci->ops == NULL) goto out; if (rpci->nreaders) { @@ -100,7 +98,7 @@ rpc_queue_upcall(struct inode *inode, st res = 0; } out: - mutex_unlock(&inode->i_mutex); + spin_unlock(&inode->i_lock); wake_up(&rpci->waitq); return res; } @@ -115,21 +113,29 @@ static void rpc_close_pipes(struct inode *inode) { struct rpc_inode *rpci = RPC_I(inode); + struct rpc_pipe_ops *ops; mutex_lock(&inode->i_mutex); - if (rpci->ops != NULL) { + ops = rpci->ops; + if (ops != NULL) { + LIST_HEAD(free_list); + + spin_lock(&inode->i_lock); rpci->nreaders = 0; - __rpc_purge_list(rpci, &rpci->in_upcall, -EPIPE); - __rpc_purge_upcall(inode, -EPIPE); - rpci->nwriters = 0; - if (rpci->ops->release_pipe) - rpci->ops->release_pipe(inode); + list_splice_init(&rpci->in_upcall, &free_list); + list_splice_init(&rpci->pipe, &free_list); + rpci->pipelen = 0; rpci->ops = NULL; + spin_unlock(&inode->i_lock); + rpc_purge_list(rpci, &free_list, ops->destroy_msg, -EPIPE); + rpci->nwriters = 0; + if (ops->release_pipe) + ops->release_pipe(inode); + cancel_delayed_work(&rpci->queue_timeout); + flush_scheduled_work(); } rpc_inode_setowner(inode, NULL); mutex_unlock(&inode->i_mutex); - cancel_delayed_work(&rpci->queue_timeout); - flush_scheduled_work(); } static struct inode * @@ -177,16 +183,26 @@ rpc_pipe_release(struct inode *inode, st goto out; msg = (struct rpc_pipe_msg *)filp->private_data; if (msg != NULL) { + spin_lock(&inode->i_lock); msg->errno = -EAGAIN; - list_del_init(&msg->list); + list_del(&msg->list); + spin_unlock(&inode->i_lock); rpci->ops->destroy_msg(msg); } if (filp->f_mode & FMODE_WRITE) rpci->nwriters --; - if (filp->f_mode & FMODE_READ) + if (filp->f_mode & FMODE_READ) { rpci->nreaders --; - if (!rpci->nreaders) - __rpc_purge_upcall(inode, -EAGAIN); + if (rpci->nreaders == 0) { + LIST_HEAD(free_list); + spin_lock(&inode->i_lock); + list_splice_init(&rpci->pipe, &free_list); + rpci->pipelen = 0; + spin_unlock(&inode->i_lock); + rpc_purge_list(rpci, &free_list, + rpci->ops->destroy_msg, -EAGAIN); + } + } if (rpci->ops->release_pipe) rpci->ops->release_pipe(inode); out: @@ -209,6 +225,7 @@ rpc_pipe_read(struct file *filp, char __ } msg = filp->private_data; if (msg == NULL) { + spin_lock(&inode->i_lock); if (!list_empty(&rpci->pipe)) { msg = list_entry(rpci->pipe.next, struct rpc_pipe_msg, @@ -218,6 +235,7 @@ rpc_pipe_read(struct file *filp, char __ filp->private_data = msg; msg->copied = 0; } + spin_unlock(&inode->i_lock); if (msg == NULL) goto out_unlock; } @@ -225,7 +243,9 @@ rpc_pipe_read(struct file *filp, char __ res = rpci->ops->upcall(filp, msg, buf, len); if (res < 0 || msg->len == msg->copied) { filp->private_data = NULL; - list_del_init(&msg->list); + spin_lock(&inode->i_lock); + list_del(&msg->list); + spin_unlock(&inode->i_lock); rpci->ops->destroy_msg(msg); } out_unlock: