From 410d591a19543f1347bc2b4b4ec3399cb548ba47 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Mon, 4 Oct 2021 09:03:53 +0800 Subject: [PATCH 1/4] kernfs: don't create a negative dentry if inactive node exists It's been reported that doing stress test for module insertion and removal can result in an ENOENT from libkmod for a valid module. In kernfs_iop_lookup() a negative dentry is created if there's no kernfs node associated with the dentry or the node is inactive. But inactive kernfs nodes are meant to be invisible to the VFS and creating a negative dentry for these can have unexpected side effects when the node transitions to an active state. The point of creating negative dentries is to avoid the expensive alloc/free cycle that occurs if there are frequent lookups for kernfs attributes that don't exist. So kernfs nodes that are not yet active should not result in a negative dentry being created so when they transition to an active state VFS lookups can create an associated dentry is a natural way. It's also been reported that https://github.com/osandov/blktests.git test block/001 hangs during the test. It was suggested that recent changes to blktests might have caused it but applying this patch resolved the problem without change to blktests. Fixes: c7e7c04274b1 ("kernfs: use VFS negative dentry caching") Tested-by: Yi Zhang ACKed-by: Al Viro Signed-off-by: Ian Kent Link: https://lore.kernel.org/r/163330943316.19450.15056895533949392922.stgit@mickey.themaw.net Signed-off-by: Greg Kroah-Hartman --- fs/kernfs/dir.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index cfc3ce8b815a..8e0a1378a4b1 100644 --- a/fs/kernfs/dir.c +++ b/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); From f729a592adb6760013c3e48622a5bf256b992452 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Wed, 29 Sep 2021 12:05:49 -0700 Subject: [PATCH 2/4] driver core: Reject pointless SYNC_STATE_ONLY device links SYNC_STATE_ONLY device links intentionally allow cycles because cyclic sync_state() dependencies are valid and necessary. However a SYNC_STATE_ONLY device link where the consumer and the supplier are the same device is pointless because the device link would be deleted as soon as the device probes (because it's also the consumer) and won't affect when the sync_state() callback is called. It's a waste of CPU cycles and memory to create this device link. So reject any attempts to create such a device link. Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag") Cc: stable Reported-by: Ulf Hansson Reviewed-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210929190549.860541-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 15986cc2fe5e..249da496581a 100644 --- a/drivers/base/core.c +++ b/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) || From 98e96cf80045a383fcc47c58dd4e87b3ae587b3e Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Tue, 28 Sep 2021 17:07:33 -0700 Subject: [PATCH 3/4] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices fw_devlink could end up creating device links for bus only devices. However, bus only devices don't get probed and can block probe() or sync_state() [1] call backs of other devices. To avoid this, probe these devices using the simple-pm-bus driver. However, there are instances of devices that are not simple buses (they get probed by their specific drivers) that also list the "simple-bus" (or other bus only compatible strings) in their compatible property to automatically populate their child devices. We still want these devices to get probed by their specific drivers. So, we make sure this driver only probes devices that are only buses. [1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/ Fixes: c442a0d18744 ("driver core: Set fw_devlink to "permissive" behavior by default") Cc: stable Cc: Rob Herring Tested-by: Saravana Kannan Tested-by: Ulf Hansson Tested-by: Geert Uytterhoeven Tested-by: Damien Le Moal Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210929000735.585237-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/bus/simple-pm-bus.c | 42 ++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c index 01a3d0cd08ed..6b8d6257ed8a 100644 --- a/drivers/bus/simple-pm-bus.c +++ b/drivers/bus/simple-pm-bus.c @@ -13,11 +13,36 @@ #include #include - static int simple_pm_bus_probe(struct platform_device *pdev) { - const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev); - struct device_node *np = pdev->dev.of_node; + const struct device *dev = &pdev->dev; + 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); From 81967efb5f3966e8692f9173c7fa2964034ece5d Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Tue, 28 Sep 2021 17:07:34 -0700 Subject: [PATCH 4/4] drivers: bus: Delete CONFIG_SIMPLE_PM_BUS The simple-pm-bus driver is mandatory for CONFIG_OF based platforms to work with fw_devlink. So, always compile it in for CONFIG_OF and delete the config since it's no longer necessary. Tested-by: Ulf Hansson Tested-by: Geert Uytterhoeven Tested-by: Damien Le Moal Cc: Rob Herring Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210929000735.585237-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- arch/arm/configs/multi_v7_defconfig | 1 - arch/arm/configs/oxnas_v6_defconfig | 1 - arch/arm/configs/shmobile_defconfig | 1 - arch/arm/mach-omap2/Kconfig | 1 - arch/arm64/configs/defconfig | 1 - drivers/bus/Kconfig | 12 ------------ drivers/bus/Makefile | 2 +- drivers/soc/canaan/Kconfig | 1 - 8 files changed, 1 insertion(+), 19 deletions(-) diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig index ba67c4717dcc..1f72c67438f9 100644 --- a/arch/arm/configs/multi_v7_defconfig +++ b/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 diff --git a/arch/arm/configs/oxnas_v6_defconfig b/arch/arm/configs/oxnas_v6_defconfig index cae0db6b4eaf..de37f7e90999 100644 --- a/arch/arm/configs/oxnas_v6_defconfig +++ b/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 diff --git a/arch/arm/configs/shmobile_defconfig b/arch/arm/configs/shmobile_defconfig index d9a27e4e0914..18d2a960b2d2 100644 --- a/arch/arm/configs/shmobile_defconfig +++ b/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 diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig index 7f13adf26e61..02c253de9b6e 100644 --- a/arch/arm/mach-omap2/Kconfig +++ b/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 diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig index 156d96afbbfc..545197bc0501 100644 --- a/arch/arm64/configs/defconfig +++ b/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 diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index a5b96f3aad67..a4cf3d692dc3 100644 --- a/drivers/bus/Kconfig +++ b/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 diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile index 1c29c5e8ffb8..52c2f35a26a9 100644 --- a/drivers/bus/Makefile +++ b/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 diff --git a/drivers/soc/canaan/Kconfig b/drivers/soc/canaan/Kconfig index 8179b69518b4..853096b7e84c 100644 --- a/drivers/soc/canaan/Kconfig +++ b/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