Merge tag 'driver-core-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the "big" set of changes to the driver core, and some drivers
  using the changes, for 5.9-rc1.

  "Biggest" thing in here is the device link exposure in sysfs, to help
  to tame the madness that is SoC device tree representations and driver
  interactions with it.

  Other stuff in here that is interesting is:

   - device probe log helper so that drivers can report problems in a
     unified way easier.

   - devres functions added

   - DEVICE_ATTR_ADMIN_* macro added to make it harder to write
     incorrect sysfs file permissions

   - documentation cleanups

   - ability for debugfs to be present in the kernel, yet not exposed to
     userspace. Needed for systems that want it enabled, but do not
     trust users, so they can still use some kernel functions that were
     otherwise disabled.

   - other minor fixes and cleanups

  The patches outside of drivers/base/ all have acks from the respective
  subsystem maintainers to go through this tree instead of theirs.

  All of these have been in linux-next with no reported issues"

* tag 'driver-core-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (39 commits)
  drm/bridge: lvds-codec: simplify error handling
  drm/bridge/sii8620: fix resource acquisition error handling
  driver core: add deferring probe reason to devices_deferred property
  driver core: add device probe log helper
  driver core: Avoid binding drivers to dead devices
  Revert "test_firmware: Test platform fw loading on non-EFI systems"
  firmware_loader: EFI firmware loader must handle pre-allocated buffer
  selftest/firmware: Add selftest timeout in settings
  test_firmware: Test platform fw loading on non-EFI systems
  driver core: Change delimiter in devlink device's name to "--"
  debugfs: Add access restriction option
  tracefs: Remove unnecessary debug_fs checks.
  driver core: Fix probe_count imbalance in really_probe()
  kobject: remove unused KOBJ_MAX action
  driver core: Fix sleeping in invalid context during device link deletion
  driver core: Add waiting_for_supplier sysfs file for devices
  driver core: Add state_synced sysfs file for devices that support it
  driver core: Expose device link details in sysfs
  driver core: Drop mention of obsolete bus rwsem from kernel-doc
  debugfs: file: Remove unnecessary cast in kfree()
  ...

3 files changed, 54 insertions, 1 deletions

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index ae49a55bda00..3753c4c484fc 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -273,7 +273,7 @@ static int full_proxy_release(struct inode *inode, struct file *filp)
 		r = real_fops->release(inode, filp);
 
 	replace_fops(filp, d_inode(dentry)->i_fop);
-	kfree((void *)proxy_fops);
+	kfree(proxy_fops);
 	fops_put(real_fops);
 	return r;
 }
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index b7f2e971ecbc..2fcf66473436 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -35,6 +35,7 @@
 static struct vfsmount *debugfs_mount;
 static int debugfs_mount_count;
 static bool debugfs_registered;
+static unsigned int debugfs_allow = DEFAULT_DEBUGFS_ALLOW_BITS;
 
 /*
  * Don't allow access attributes to be changed whilst the kernel is locked down
@@ -266,6 +267,9 @@ static struct dentry *debug_mount(struct file_system_type *fs_type,
 			int flags, const char *dev_name,
 			void *data)
 {
+	if (!(debugfs_allow & DEBUGFS_ALLOW_API))
+		return ERR_PTR(-EPERM);
+
 	return mount_single(fs_type, flags, data, debug_fill_super);
 }
 
@@ -311,6 +315,9 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	struct dentry *dentry;
 	int error;
 
+	if (!(debugfs_allow & DEBUGFS_ALLOW_API))
+		return ERR_PTR(-EPERM);
+
 	pr_debug("creating file '%s'\n", name);
 
 	if (IS_ERR(parent))
@@ -385,6 +392,11 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 	if (IS_ERR(dentry))
 		return dentry;
 
+	if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
+		failed_creating(dentry);
+		return ERR_PTR(-EPERM);
+	}
+
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
 		pr_err("out of free dentries, can not create file '%s'\n",
@@ -541,6 +553,11 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 	if (IS_ERR(dentry))
 		return dentry;
 
+	if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
+		failed_creating(dentry);
+		return ERR_PTR(-EPERM);
+	}
+
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
 		pr_err("out of free dentries, can not create directory '%s'\n",
@@ -583,6 +600,11 @@ struct dentry *debugfs_create_automount(const char *name,
 	if (IS_ERR(dentry))
 		return dentry;
 
+	if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
+		failed_creating(dentry);
+		return ERR_PTR(-EPERM);
+	}
+
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
 		pr_err("out of free dentries, can not create automount '%s'\n",
@@ -786,10 +808,27 @@ bool debugfs_initialized(void)
 }
 EXPORT_SYMBOL_GPL(debugfs_initialized);
 
+static int __init debugfs_kernel(char *str)
+{
+	if (str) {
+		if (!strcmp(str, "on"))
+			debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
+		else if (!strcmp(str, "no-mount"))
+			debugfs_allow = DEBUGFS_ALLOW_API;
+		else if (!strcmp(str, "off"))
+			debugfs_allow = 0;
+	}
+
+	return 0;
+}
+early_param("debugfs", debugfs_kernel);
 static int __init debugfs_init(void)
 {
 	int retval;
 
+	if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
+		return -EPERM;
+
 	retval = sysfs_create_mount_point(kernel_kobj, "debug");
 	if (retval)
 		return retval;
diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h
index 034e6973cead..92af8ae31313 100644
--- a/fs/debugfs/internal.h
+++ b/fs/debugfs/internal.h
@@ -29,4 +29,18 @@ struct debugfs_fsdata {
  */
 #define DEBUGFS_FSDATA_IS_REAL_FOPS_BIT BIT(0)
 
+/* Access BITS */
+#define DEBUGFS_ALLOW_API	BIT(0)
+#define DEBUGFS_ALLOW_MOUNT	BIT(1)
+
+#ifdef CONFIG_DEBUG_FS_ALLOW_ALL
+#define DEFAULT_DEBUGFS_ALLOW_BITS (DEBUGFS_ALLOW_MOUNT | DEBUGFS_ALLOW_API)
+#endif
+#ifdef CONFIG_DEBUG_FS_DISALLOW_MOUNT
+#define DEFAULT_DEBUGFS_ALLOW_BITS (DEBUGFS_ALLOW_API)
+#endif
+#ifdef CONFIG_DEBUG_FS_ALLOW_NONE
+#define DEFAULT_DEBUGFS_ALLOW_BITS (0)
+#endif
+
 #endif /* _DEBUGFS_INTERNAL_H_ */