sysfs: Remove sysfs_get/put_active_two

It turns out that holding an active reference on a directory is
pointless.  The purpose of the active references are to allows us to
block when removing sysfs entries that have custom methods so we don't
remove modules while running modular code and to keep those custom
methods from accessing data structures after the files have been
removed.  Further sysfs_remove_dir remove all elements in the
directory before removing the directory itself, so there is no chance
we will remove a directory with active children.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index a0a500af24a14d81f13d121f39915bd9dc1e59a2..e9d293593e52f79bc51bef2bbc352898b9bdd1ee 100644 (file)
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -54,14 +54,14 @@ fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
        int rc;
 
        /* need attr_sd for attr, its parent for kobj */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -ENODEV;
 
        rc = -EIO;
        if (attr->read)
                rc = attr->read(kobj, attr, buffer, off, count);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 
        return rc;
 }
@@ -125,14 +125,14 @@ flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
        int rc;
 
        /* need attr_sd for attr, its parent for kobj */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -ENODEV;
 
        rc = -EIO;
        if (attr->write)
                rc = attr->write(kobj, attr, buffer, offset, count);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 
        return rc;
 }
@@ -184,12 +184,12 @@ static void bin_vma_open(struct vm_area_struct *vma)
        if (!bb->vm_ops || !bb->vm_ops->open)
                return;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return;
 
        bb->vm_ops->open(vma);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 }
 
 static void bin_vma_close(struct vm_area_struct *vma)
@@ -201,12 +201,12 @@ static void bin_vma_close(struct vm_area_struct *vma)
        if (!bb->vm_ops || !bb->vm_ops->close)
                return;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return;
 
        bb->vm_ops->close(vma);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 }
 
 static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
@@ -219,12 +219,12 @@ static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
        if (!bb->vm_ops || !bb->vm_ops->fault)
                return VM_FAULT_SIGBUS;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return VM_FAULT_SIGBUS;
 
        ret = bb->vm_ops->fault(vma, vmf);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return ret;
 }
 
@@ -241,12 +241,12 @@ static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
        if (!bb->vm_ops->page_mkwrite)
                return 0;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return VM_FAULT_SIGBUS;
 
        ret = bb->vm_ops->page_mkwrite(vma, vmf);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return ret;
 }
 
@@ -261,12 +261,12 @@ static int bin_access(struct vm_area_struct *vma, unsigned long addr,
        if (!bb->vm_ops || !bb->vm_ops->access)
                return -EINVAL;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -EINVAL;
 
        ret = bb->vm_ops->access(vma, addr, buf, len, write);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return ret;
 }
 
@@ -281,12 +281,12 @@ static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
        if (!bb->vm_ops || !bb->vm_ops->set_policy)
                return 0;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -EINVAL;
 
        ret = bb->vm_ops->set_policy(vma, new);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return ret;
 }
 
@@ -301,12 +301,12 @@ static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
        if (!bb->vm_ops || !bb->vm_ops->get_policy)
                return vma->vm_policy;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return vma->vm_policy;
 
        pol = bb->vm_ops->get_policy(vma, addr);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return pol;
 }
 
@@ -321,12 +321,12 @@ static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
        if (!bb->vm_ops || !bb->vm_ops->migrate)
                return 0;
 
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return 0;
 
        ret = bb->vm_ops->migrate(vma, from, to, flags);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return ret;
 }
 #endif
@@ -356,7 +356,7 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
 
        /* need attr_sd for attr, its parent for kobj */
        rc = -ENODEV;
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                goto out_unlock;
 
        rc = -EINVAL;
@@ -384,7 +384,7 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
        bb->vm_ops = vma->vm_ops;
        vma->vm_ops = &bin_vm_ops;
 out_put:
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 out_unlock:
        mutex_unlock(&bb->mutex);
 
@@ -399,7 +399,7 @@ static int open(struct inode * inode, struct file * file)
        int error;
 
        /* binary file operations requires both @sd and its parent */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -ENODEV;
 
        error = -EACCES;
@@ -426,11 +426,11 @@ static int open(struct inode * inode, struct file * file)
        mutex_unlock(&sysfs_bin_lock);
 
        /* open succeeded, put active references */
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return 0;
 
  err_out:
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        kfree(bb);
        return error;
 }

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5c4703d751b50ba877f4d3b1f0aadeaa814edfe2..1bdc42f4fd93a92db8e2cd486103afc272f729b5 100644 (file)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -93,7 +93,7 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
  *     RETURNS:
  *     Pointer to @sd on success, NULL on failure.
  */
-static struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
 {
        if (unlikely(!sd))
                return NULL;
@@ -124,7 +124,7 @@ static struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
  *     Put an active reference to @sd.  This function is noop if @sd
  *     is NULL.
  */
-static void sysfs_put_active(struct sysfs_dirent *sd)
+void sysfs_put_active(struct sysfs_dirent *sd)
 {
        struct completion *cmpl;
        int v;
@@ -144,45 +144,6 @@ static void sysfs_put_active(struct sysfs_dirent *sd)
        complete(cmpl);
 }
 
-/**
- *     sysfs_get_active_two - get active references to sysfs_dirent and parent
- *     @sd: sysfs_dirent of interest
- *
- *     Get active reference to @sd and its parent.  Parent's active
- *     reference is grabbed first.  This function is noop if @sd is
- *     NULL.
- *
- *     RETURNS:
- *     Pointer to @sd on success, NULL on failure.
- */
-struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
-{
-       if (sd) {
-               if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
-                       return NULL;
-               if (unlikely(!sysfs_get_active(sd))) {
-                       sysfs_put_active(sd->s_parent);
-                       return NULL;
-               }
-       }
-       return sd;
-}
-
-/**
- *     sysfs_put_active_two - put active references to sysfs_dirent and parent
- *     @sd: sysfs_dirent of interest
- *
- *     Put active references to @sd and its parent.  This function is
- *     noop if @sd is NULL.
- */
-void sysfs_put_active_two(struct sysfs_dirent *sd)
-{
-       if (sd) {
-               sysfs_put_active(sd);
-               sysfs_put_active(sd->s_parent);
-       }
-}
-
 /**
  *     sysfs_deactivate - deactivate sysfs_dirent
  *     @sd: sysfs_dirent to deactivate

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index ced2299f1c9a3286443dbb4796f9691e82fe2d5e..40961366e929ac4d1a18a3f13a2e5dc7494b90d6 100644 (file)
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -85,13 +85,13 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer
                return -ENOMEM;
 
        /* need attr_sd for attr and ops, its parent for kobj */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -ENODEV;
 
        buffer->event = atomic_read(&attr_sd->s_attr.open->event);
        count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 
        /*
         * The code works fine with PAGE_SIZE return but it's likely to
@@ -203,12 +203,12 @@ flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t
        int rc;
 
        /* need attr_sd for attr and ops, its parent for kobj */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -ENODEV;
 
        rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 
        return rc;
 }
@@ -344,7 +344,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
                memmove(last_sysfs_file, p, strlen(p) + 1);
 
        /* need attr_sd for attr and ops, its parent for kobj */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                return -ENODEV;
 
        /* every kobject with an attribute needs a ktype assigned */
@@ -393,13 +393,13 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
                goto err_free;
 
        /* open succeeded, put active references */
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return 0;
 
  err_free:
        kfree(buffer);
  err_out:
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
        return error;
 }
 
@@ -437,12 +437,12 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
        struct sysfs_open_dirent *od = attr_sd->s_attr.open;
 
        /* need parent for the kobj, grab both */
-       if (!sysfs_get_active_two(attr_sd))
+       if (!sysfs_get_active(attr_sd))
                goto trigger;
 
        poll_wait(filp, &od->poll, wait);
 
-       sysfs_put_active_two(attr_sd);
+       sysfs_put_active(attr_sd);
 
        if (buffer->event != atomic_read(&od->event))
                goto trigger;

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index cdd9377a6e06a9d3d5fafc18e295bb8b5565b662..bb7723c4f5a5f4997bf5eb35f9abc8635273863b 100644 (file)
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -124,8 +124,8 @@ extern const struct file_operations sysfs_dir_operations;
 extern const struct inode_operations sysfs_dir_inode_operations;
 
 struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
-struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
-void sysfs_put_active_two(struct sysfs_dirent *sd);
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
+void sysfs_put_active(struct sysfs_dirent *sd);
 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
                       struct sysfs_dirent *parent_sd);
 int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);