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SUNRPC: rpc_timeout_upcall_queue should not sleep
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 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 <Trond.Myklebust@netapp.com>
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Trond Myklebust authored and Trond Myklebust committed Feb 1, 2006
1 parent 8a31776 commit 9842ef3
Showing 1 changed file with 58 additions and 38 deletions.
96 changes: 58 additions & 38 deletions net/sunrpc/rpc_pipe.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -38,44 +38,42 @@ static kmem_cache_t *rpc_inode_cachep __read_mostly;

#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
Expand All @@ -84,7 +82,7 @@ rpc_queue_upcall(struct inode *inode, struct rpc_pipe_msg *msg)
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) {
Expand All @@ -100,7 +98,7 @@ rpc_queue_upcall(struct inode *inode, struct rpc_pipe_msg *msg)
res = 0;
}
out:
mutex_unlock(&inode->i_mutex);
spin_unlock(&inode->i_lock);
wake_up(&rpci->waitq);
return res;
}
Expand All @@ -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 *
Expand Down Expand Up @@ -177,16 +183,26 @@ rpc_pipe_release(struct inode *inode, struct file *filp)
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:
Expand All @@ -209,6 +225,7 @@ rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
}
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,
Expand All @@ -218,14 +235,17 @@ rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
filp->private_data = msg;
msg->copied = 0;
}
spin_unlock(&inode->i_lock);
if (msg == NULL)
goto out_unlock;
}
/* NOTE: it is up to the callback to update msg->copied */
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:
Expand Down

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