diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/kernfs/dir.c | 31 | ||||
| -rw-r--r-- | fs/kernfs/file.c | 47 |
2 files changed, 45 insertions, 33 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index e205fde7163a..6eca72cfa1f2 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -18,7 +18,15 @@ #include "kernfs-internal.h" static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ -static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */ +/* + * Don't use rename_lock to piggy back on pr_cont_buf. We don't want to + * call pr_cont() while holding rename_lock. Because sometimes pr_cont() + * will perform wakeups when releasing console_sem. Holding rename_lock + * will introduce deadlock if the scheduler reads the kernfs_name in the + * wakeup path. + */ +static DEFINE_SPINLOCK(kernfs_pr_cont_lock); +static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by pr_cont_lock */ static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) @@ -229,12 +237,12 @@ void pr_cont_kernfs_name(struct kernfs_node *kn) { unsigned long flags; - spin_lock_irqsave(&kernfs_rename_lock, flags); + spin_lock_irqsave(&kernfs_pr_cont_lock, flags); - kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); + kernfs_name(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); pr_cont("%s", kernfs_pr_cont_buf); - spin_unlock_irqrestore(&kernfs_rename_lock, flags); + spin_unlock_irqrestore(&kernfs_pr_cont_lock, flags); } /** @@ -248,10 +256,10 @@ void pr_cont_kernfs_path(struct kernfs_node *kn) unsigned long flags; int sz; - spin_lock_irqsave(&kernfs_rename_lock, flags); + spin_lock_irqsave(&kernfs_pr_cont_lock, flags); - sz = kernfs_path_from_node_locked(kn, NULL, kernfs_pr_cont_buf, - sizeof(kernfs_pr_cont_buf)); + sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf, + sizeof(kernfs_pr_cont_buf)); if (sz < 0) { pr_cont("(error)"); goto out; @@ -265,7 +273,7 @@ void pr_cont_kernfs_path(struct kernfs_node *kn) pr_cont("%s", kernfs_pr_cont_buf); out: - spin_unlock_irqrestore(&kernfs_rename_lock, flags); + spin_unlock_irqrestore(&kernfs_pr_cont_lock, flags); } /** @@ -823,13 +831,12 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem); - /* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */ - spin_lock_irq(&kernfs_rename_lock); + spin_lock_irq(&kernfs_pr_cont_lock); len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); if (len >= sizeof(kernfs_pr_cont_buf)) { - spin_unlock_irq(&kernfs_rename_lock); + spin_unlock_irq(&kernfs_pr_cont_lock); return NULL; } @@ -841,7 +848,7 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, parent = kernfs_find_ns(parent, name, ns); } - spin_unlock_irq(&kernfs_rename_lock); + spin_unlock_irq(&kernfs_pr_cont_lock); return parent; } diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 88423069407c..e3abfa843879 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -33,7 +33,6 @@ static DEFINE_SPINLOCK(kernfs_open_node_lock); static DEFINE_MUTEX(kernfs_open_file_mutex); struct kernfs_open_node { - atomic_t refcnt; atomic_t event; wait_queue_head_t poll; struct list_head files; /* goes through kernfs_open_file.list */ @@ -530,10 +529,8 @@ static int kernfs_get_open_node(struct kernfs_node *kn, } on = kn->attr.open; - if (on) { - atomic_inc(&on->refcnt); + if (on) list_add_tail(&of->list, &on->files); - } spin_unlock_irq(&kernfs_open_node_lock); mutex_unlock(&kernfs_open_file_mutex); @@ -548,7 +545,6 @@ static int kernfs_get_open_node(struct kernfs_node *kn, if (!new_on) return -ENOMEM; - atomic_set(&new_on->refcnt, 0); atomic_set(&new_on->event, 1); init_waitqueue_head(&new_on->poll); INIT_LIST_HEAD(&new_on->files); @@ -556,17 +552,19 @@ static int kernfs_get_open_node(struct kernfs_node *kn, } /** - * kernfs_put_open_node - put kernfs_open_node - * @kn: target kernfs_nodet + * kernfs_unlink_open_file - Unlink @of from @kn. + * + * @kn: target kernfs_node * @of: associated kernfs_open_file * - * Put @kn->attr.open and unlink @of from the files list. If - * reference count reaches zero, disassociate and free it. + * Unlink @of from list of @kn's associated open files. If list of + * associated open files becomes empty, disassociate and free + * kernfs_open_node. * * LOCKING: * None. */ -static void kernfs_put_open_node(struct kernfs_node *kn, +static void kernfs_unlink_open_file(struct kernfs_node *kn, struct kernfs_open_file *of) { struct kernfs_open_node *on = kn->attr.open; @@ -578,7 +576,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn, if (of) list_del(&of->list); - if (atomic_dec_and_test(&on->refcnt)) + if (list_empty(&on->files)) kn->attr.open = NULL; else on = NULL; @@ -706,7 +704,7 @@ static int kernfs_fop_open(struct inode *inode, struct file *file) return 0; err_put_node: - kernfs_put_open_node(kn, of); + kernfs_unlink_open_file(kn, of); err_seq_release: seq_release(inode, file); err_free: @@ -752,7 +750,7 @@ static int kernfs_fop_release(struct inode *inode, struct file *filp) mutex_unlock(&kernfs_open_file_mutex); } - kernfs_put_open_node(kn, of); + kernfs_unlink_open_file(kn, of); seq_release(inode, filp); kfree(of->prealloc_buf); kfree(of); @@ -768,15 +766,24 @@ void kernfs_drain_open_files(struct kernfs_node *kn) if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE))) return; - spin_lock_irq(&kernfs_open_node_lock); - on = kn->attr.open; - if (on) - atomic_inc(&on->refcnt); - spin_unlock_irq(&kernfs_open_node_lock); - if (!on) + /* + * lockless opportunistic check is safe below because no one is adding to + * ->attr.open at this point of time. This check allows early bail out + * if ->attr.open is already NULL. kernfs_unlink_open_file makes + * ->attr.open NULL only while holding kernfs_open_file_mutex so below + * check under kernfs_open_file_mutex will ensure bailing out if + * ->attr.open became NULL while waiting for the mutex. + */ + if (!kn->attr.open) return; mutex_lock(&kernfs_open_file_mutex); + if (!kn->attr.open) { + mutex_unlock(&kernfs_open_file_mutex); + return; + } + + on = kn->attr.open; list_for_each_entry(of, &on->files, list) { struct inode *inode = file_inode(of->file); @@ -789,8 +796,6 @@ void kernfs_drain_open_files(struct kernfs_node *kn) } mutex_unlock(&kernfs_open_file_mutex); - - kernfs_put_open_node(kn, NULL); } /* |