Driver core fixes for 5.15-rc6

Here are some small driver core fixes for 5.15-rc6, all of which have
 been in linux-next for a while with no reported issues.
 
 They include:
 	- kernfs negative dentry bugfix
 	- simple pm bus fixes to resolve reported issues
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here are some small driver core fixes for 5.15-rc6, all of which have
  been in linux-next for a while with no reported issues.

  They include:

   - kernfs negative dentry bugfix

   - simple pm bus fixes to resolve reported issues"

* tag 'driver-core-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  drivers: bus: Delete CONFIG_SIMPLE_PM_BUS
  drivers: bus: simple-pm-bus: Add support for probing simple bus only devices
  driver core: Reject pointless SYNC_STATE_ONLY device links
  kernfs: don't create a negative dentry if inactive node exists

arch/arm/configs/multi_v7_defconfig

@@ -197,7 +197,6 @@ CONFIG_PCI_EPF_TEST=m
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_OMAP_OCP2SCP=y
-CONFIG_SIMPLE_PM_BUS=y
 CONFIG_MTD=y
 CONFIG_MTD_CMDLINE_PARTS=y
 CONFIG_MTD_BLOCK=y

arch/arm/configs/oxnas_v6_defconfig

@@ -46,7 +46,6 @@ CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DMA_CMA=y
 CONFIG_CMA_SIZE_MBYTES=64
-CONFIG_SIMPLE_PM_BUS=y
 CONFIG_MTD=y
 CONFIG_MTD_CMDLINE_PARTS=y
 CONFIG_MTD_BLOCK=y

arch/arm/configs/shmobile_defconfig

@@ -40,7 +40,6 @@ CONFIG_PCI_RCAR_GEN2=y
 CONFIG_PCIE_RCAR_HOST=y
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
-CONFIG_SIMPLE_PM_BUS=y
 CONFIG_MTD=y
 CONFIG_MTD_BLOCK=y
 CONFIG_MTD_CFI=y

arch/arm/mach-omap2/Kconfig

@@ -112,7 +112,6 @@ config ARCH_OMAP2PLUS
 	select PM_GENERIC_DOMAINS
 	select PM_GENERIC_DOMAINS_OF
 	select RESET_CONTROLLER
-	select SIMPLE_PM_BUS
 	select SOC_BUS
 	select TI_SYSC
 	select OMAP_IRQCHIP

arch/arm64/configs/defconfig

@@ -245,7 +245,6 @@ CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_FW_LOADER_USER_HELPER=y
 CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
 CONFIG_HISILICON_LPC=y
-CONFIG_SIMPLE_PM_BUS=y
 CONFIG_FSL_MC_BUS=y
 CONFIG_TEGRA_ACONNECT=m
 CONFIG_GNSS=m

drivers/base/core.c

@@ -687,7 +687,8 @@ struct device_link *device_link_add(struct device *consumer,
 {
 	struct device_link *link;
 
-	if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS ||
+	if (!consumer || !supplier || consumer == supplier ||
+	    flags & ~DL_ADD_VALID_FLAGS ||
 	    (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
 	    (flags & DL_FLAG_SYNC_STATE_ONLY &&
 	     (flags & ~DL_FLAG_INFERRED) != DL_FLAG_SYNC_STATE_ONLY) ||

drivers/bus/Kconfig

@@ -152,18 +152,6 @@ config QCOM_EBI2
 	  Interface 2, which can be used to connect things like NAND Flash,
 	  SRAM, ethernet adapters, FPGAs and LCD displays.
 
-config SIMPLE_PM_BUS
-	tristate "Simple Power-Managed Bus Driver"
-	depends on OF && PM
-	help
-	  Driver for transparent busses that don't need a real driver, but
-	  where the bus controller is part of a PM domain, or under the control
-	  of a functional clock, and thus relies on runtime PM for managing
-	  this PM domain and/or clock.
-	  An example of such a bus controller is the Renesas Bus State
-	  Controller (BSC, sometimes called "LBSC within Bus Bridge", or
-	  "External Bus Interface") as found on several Renesas ARM SoCs.
-
 config SUN50I_DE2_BUS
 	bool "Allwinner A64 DE2 Bus Driver"
 	  default ARM64

drivers/bus/Makefile

@@ -27,7 +27,7 @@ obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
 obj-$(CONFIG_QCOM_EBI2)		+= qcom-ebi2.o
 obj-$(CONFIG_SUN50I_DE2_BUS)	+= sun50i-de2.o
 obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
-obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o
+obj-$(CONFIG_OF)		+= simple-pm-bus.o
 obj-$(CONFIG_TEGRA_ACONNECT)	+= tegra-aconnect.o
 obj-$(CONFIG_TEGRA_GMI)		+= tegra-gmi.o
 obj-$(CONFIG_TI_PWMSS)		+= ti-pwmss.o

drivers/bus/simple-pm-bus.c

@@ -13,11 +13,36 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 
-
 static int simple_pm_bus_probe(struct platform_device *pdev)
 {
-	const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev);
+	const struct device *dev = &pdev->dev;
-	struct device_node *np = pdev->dev.of_node;
+	const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
+	struct device_node *np = dev->of_node;
+	const struct of_device_id *match;
+
+	/*
+	 * Allow user to use driver_override to bind this driver to a
+	 * transparent bus device which has a different compatible string
+	 * that's not listed in simple_pm_bus_of_match. We don't want to do any
+	 * of the simple-pm-bus tasks for these devices, so return early.
+	 */
+	if (pdev->driver_override)
+		return 0;
+
+	match = of_match_device(dev->driver->of_match_table, dev);
+	/*
+	 * These are transparent bus devices (not simple-pm-bus matches) that
+	 * have their child nodes populated automatically.  So, don't need to
+	 * do anything more. We only match with the device if this driver is
+	 * the most specific match because we don't want to incorrectly bind to
+	 * a device that has a more specific driver.
+	 */
+	if (match && match->data) {
+		if (of_property_match_string(np, "compatible", match->compatible) == 0)
+			return 0;
+		else
+			return -ENODEV;
+	}
 
 	dev_dbg(&pdev->dev, "%s\n", __func__);
 
@@ -31,14 +56,25 @@ static int simple_pm_bus_probe(struct platform_device *pdev)
 
 static int simple_pm_bus_remove(struct platform_device *pdev)
 {
+	const void *data = of_device_get_match_data(&pdev->dev);
+
+	if (pdev->driver_override || data)
+		return 0;
+
 	dev_dbg(&pdev->dev, "%s\n", __func__);
 
 	pm_runtime_disable(&pdev->dev);
 	return 0;
 }
 
+#define ONLY_BUS	((void *) 1) /* Match if the device is only a bus. */
+
 static const struct of_device_id simple_pm_bus_of_match[] = {
 	{ .compatible = "simple-pm-bus", },
+	{ .compatible = "simple-bus",	.data = ONLY_BUS },
+	{ .compatible = "simple-mfd",	.data = ONLY_BUS },
+	{ .compatible = "isa",		.data = ONLY_BUS },
+	{ .compatible = "arm,amba-bus",	.data = ONLY_BUS },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match);

drivers/soc/canaan/Kconfig

@@ -5,7 +5,6 @@ config SOC_K210_SYSCTL
 	depends on RISCV && SOC_CANAAN && OF
 	default SOC_CANAAN
         select PM
-        select SIMPLE_PM_BUS
         select SYSCON
         select MFD_SYSCON
 	help

fs/kernfs/dir.c

@@ -1111,7 +1111,14 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
 
 	kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
 	/* attach dentry and inode */
-	if (kn && kernfs_active(kn)) {
+	if (kn) {
+		/* Inactive nodes are invisible to the VFS so don't
+		 * create a negative.
+		 */
+		if (!kernfs_active(kn)) {
+			up_read(&kernfs_rwsem);
+			return NULL;
+		}
 		inode = kernfs_get_inode(dir->i_sb, kn);
 		if (!inode)
 			inode = ERR_PTR(-ENOMEM);