From 0462c56c290a99a7f03e817ae5b843116dfb575c Mon Sep 17 00:00:00 2001 From: Herve Codina Date: Mon, 25 Mar 2024 16:21:25 +0100 Subject: driver core: Introduce device_link_wait_removal() The commit 80dd33cf72d1 ("drivers: base: Fix device link removal") introduces a workqueue to release the consumer and supplier devices used in the devlink. In the job queued, devices are release and in turn, when all the references to these devices are dropped, the release function of the device itself is called. Nothing is present to provide some synchronisation with this workqueue in order to ensure that all ongoing releasing operations are done and so, some other operations can be started safely. For instance, in the following sequence: 1) of_platform_depopulate() 2) of_overlay_remove() During the step 1, devices are released and related devlinks are removed (jobs pushed in the workqueue). During the step 2, OF nodes are destroyed but, without any synchronisation with devlink removal jobs, of_overlay_remove() can raise warnings related to missing of_node_put(): ERROR: memory leak, expected refcount 1 instead of 2 Indeed, the missing of_node_put() call is going to be done, too late, from the workqueue job execution. Introduce device_link_wait_removal() to offer a way to synchronize operations waiting for the end of devlink removals (i.e. end of workqueue jobs). Also, as a flushing operation is done on the workqueue, the workqueue used is moved from a system-wide workqueue to a local one. Cc: stable@vger.kernel.org Signed-off-by: Herve Codina Tested-by: Luca Ceresoli Reviewed-by: Nuno Sa Reviewed-by: Saravana Kannan Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20240325152140.198219-2-herve.codina@bootlin.com Signed-off-by: Rob Herring --- drivers/base/core.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index b93f3c5716ae..5f4e03336e68 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -44,6 +44,7 @@ static bool fw_devlink_is_permissive(void); static void __fw_devlink_link_to_consumers(struct device *dev); static bool fw_devlink_drv_reg_done; static bool fw_devlink_best_effort; +static struct workqueue_struct *device_link_wq; /** * __fwnode_link_add - Create a link between two fwnode_handles. @@ -533,12 +534,26 @@ static void devlink_dev_release(struct device *dev) /* * It may take a while to complete this work because of the SRCU * synchronization in device_link_release_fn() and if the consumer or - * supplier devices get deleted when it runs, so put it into the "long" - * workqueue. + * supplier devices get deleted when it runs, so put it into the + * dedicated workqueue. */ - queue_work(system_long_wq, &link->rm_work); + queue_work(device_link_wq, &link->rm_work); } +/** + * device_link_wait_removal - Wait for ongoing devlink removal jobs to terminate + */ +void device_link_wait_removal(void) +{ + /* + * devlink removal jobs are queued in the dedicated work queue. + * To be sure that all removal jobs are terminated, ensure that any + * scheduled work has run to completion. + */ + flush_workqueue(device_link_wq); +} +EXPORT_SYMBOL_GPL(device_link_wait_removal); + static struct class devlink_class = { .name = "devlink", .dev_groups = devlink_groups, @@ -4164,9 +4179,14 @@ int __init devices_init(void) sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj); if (!sysfs_dev_char_kobj) goto char_kobj_err; + device_link_wq = alloc_workqueue("device_link_wq", 0, 0); + if (!device_link_wq) + goto wq_err; return 0; + wq_err: + kobject_put(sysfs_dev_char_kobj); char_kobj_err: kobject_put(sysfs_dev_block_kobj); block_kobj_err: -- cgit v1.2.3-59-g8ed1b From 0bb322be5d389c00740d884351d4ba08fca938aa Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Mon, 25 Mar 2024 17:14:09 -0500 Subject: driver core: Remove unused platform_notify, platform_notify_remove The "platform_notify" and "platform_notify_remove" hooks have been unused since 00ba9357d189 ("ARM: ixp4xx: Drop custom DMA coherency and bouncing"). Remove "platform_notify" and "platform_notify_remove". No functional change intended. Signed-off-by: Bjorn Helgaas Cc: Heikki Krogerus Cc: Linus Walleij Reviewed-by: Andy Shevchenko Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20240325221409.1457036-1-helgaas@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 8 -------- include/linux/device.h | 11 ----------- 2 files changed, 19 deletions(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index b93f3c5716ae..78dfa74ee18b 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2331,8 +2331,6 @@ static void fw_devlink_link_device(struct device *dev) /* Device links support end. */ -int (*platform_notify)(struct device *dev) = NULL; -int (*platform_notify_remove)(struct device *dev) = NULL; static struct kobject *dev_kobj; /* /sys/dev/char */ @@ -2380,16 +2378,10 @@ static void device_platform_notify(struct device *dev) acpi_device_notify(dev); software_node_notify(dev); - - if (platform_notify) - platform_notify(dev); } static void device_platform_notify_remove(struct device *dev) { - if (platform_notify_remove) - platform_notify_remove(dev); - software_node_notify_remove(dev); acpi_device_notify_remove(dev); diff --git a/include/linux/device.h b/include/linux/device.h index 97c4b046c09d..c515ba5756e4 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -1206,17 +1206,6 @@ int __must_check devm_device_add_groups(struct device *dev, int __must_check devm_device_add_group(struct device *dev, const struct attribute_group *grp); -/* - * Platform "fixup" functions - allow the platform to have their say - * about devices and actions that the general device layer doesn't - * know about. - */ -/* Notify platform of device discovery */ -extern int (*platform_notify)(struct device *dev); - -extern int (*platform_notify_remove)(struct device *dev); - - /* * get_device - atomically increment the reference count for the device. * -- cgit v1.2.3-59-g8ed1b From 3cc50d07be10f67aff836f8247a240ec132c6a67 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Sat, 20 Apr 2024 22:00:01 +0200 Subject: driver core: Add device_show_string() helper for sysfs attributes For drivers wishing to expose an unsigned long, int or bool at a static memory location in sysfs, the driver core provides ready-made helpers such as device_show_ulong() to be used as ->show() callback. Some drivers need to expose a string and so far they all provide their own ->show() implementation. arch/powerpc/perf/hv-24x7.c went so far as to create a device_show_string() helper but kept it private. Make it public for reuse by other drivers. The pattern seems to be sufficiently frequent to merit a public helper. Add a DEVICE_STRING_ATTR_RO() macro in line with the existing DEVICE_ULONG_ATTR() and similar macros to ease declaration of string attributes. Signed-off-by: Lukas Wunner Acked-by: Michael Ellerman Link: https://lore.kernel.org/r/2e3eaaf2600bb55c0415c23ba301e809403a7aa2.1713608122.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/perf/hv-24x7.c | 10 ---------- drivers/base/core.c | 9 +++++++++ include/linux/device.h | 15 +++++++++++++++ 3 files changed, 24 insertions(+), 10 deletions(-) (limited to 'drivers/base/core.c') diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c index 057ec2e3451d..d400fa391c27 100644 --- a/arch/powerpc/perf/hv-24x7.c +++ b/arch/powerpc/perf/hv-24x7.c @@ -425,16 +425,6 @@ static char *memdup_to_str(char *maybe_str, int max_len, gfp_t gfp) return kasprintf(gfp, "%.*s", max_len, maybe_str); } -static ssize_t device_show_string(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct dev_ext_attribute *d; - - d = container_of(attr, struct dev_ext_attribute, attr); - - return sprintf(buf, "%s\n", (char *)d->var); -} - static ssize_t cpumask_show(struct device *dev, struct device_attribute *attr, char *buf) { diff --git a/drivers/base/core.c b/drivers/base/core.c index 4d51928c4088..131d96c6090b 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2538,6 +2538,15 @@ ssize_t device_show_bool(struct device *dev, struct device_attribute *attr, } EXPORT_SYMBOL_GPL(device_show_bool); +ssize_t device_show_string(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct dev_ext_attribute *ea = to_ext_attr(attr); + + return sysfs_emit(buf, "%s\n", (char *)ea->var); +} +EXPORT_SYMBOL_GPL(device_show_string); + /** * device_release - free device structure. * @kobj: device's kobject. diff --git a/include/linux/device.h b/include/linux/device.h index 07f4d2af1e3c..b6b6ff881a3f 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -132,6 +132,8 @@ ssize_t device_show_bool(struct device *dev, struct device_attribute *attr, char *buf); ssize_t device_store_bool(struct device *dev, struct device_attribute *attr, const char *buf, size_t count); +ssize_t device_show_string(struct device *dev, struct device_attribute *attr, + char *buf); /** * DEVICE_ATTR - Define a device attribute. @@ -251,6 +253,19 @@ ssize_t device_store_bool(struct device *dev, struct device_attribute *attr, struct dev_ext_attribute dev_attr_##_name = \ { __ATTR(_name, _mode, device_show_bool, device_store_bool), &(_var) } +/** + * DEVICE_STRING_ATTR_RO - Define a device attribute backed by a r/o string. + * @_name: Attribute name. + * @_mode: File mode. + * @_var: Identifier of string. + * + * Like DEVICE_ULONG_ATTR(), but @_var is a string. Because the length of the + * string allocation is unknown, the attribute must be read-only. + */ +#define DEVICE_STRING_ATTR_RO(_name, _mode, _var) \ + struct dev_ext_attribute dev_attr_##_name = \ + { __ATTR(_name, (_mode) & ~0222, device_show_string, NULL), (_var) } + #define DEVICE_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ struct device_attribute dev_attr_##_name = \ __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) -- cgit v1.2.3-59-g8ed1b