[v6,3/5] Implement modalias sysfs attribute for modules
Commit Message
When the modalias attribute is read, invoke a subsystem-specific
callback for each driver registered by the specific module.
The intent of the new modalias attribute is to expose the
match-id-based modaliases to userspace for builtin and loaded kernel
modules.
Signed-off-by: Allen Webb <allenwebb@google.com>
---
include/linux/device/bus.h | 7 +++++
kernel/module/sysfs.c | 57 +++++++++++++++++++++++++++++++++++++-
2 files changed, 63 insertions(+), 1 deletion(-)
Comments
Le 02/12/2022 à 23:47, Allen Webb a écrit :
> When the modalias attribute is read, invoke a subsystem-specific
> callback for each driver registered by the specific module.
>
> The intent of the new modalias attribute is to expose the
> match-id-based modaliases to userspace for builtin and loaded kernel
> modules.
>
> Signed-off-by: Allen Webb <allenwebb@google.com>
> ---
> include/linux/device/bus.h | 7 +++++
> kernel/module/sysfs.c | 57 +++++++++++++++++++++++++++++++++++++-
> 2 files changed, 63 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h
> index 82a5583437099..cce0bedec63d9 100644
> --- a/include/linux/device/bus.h
> +++ b/include/linux/device/bus.h
> @@ -61,6 +61,10 @@ struct fwnode_handle;
> * this bus.
> * @dma_cleanup: Called to cleanup DMA configuration on a device on
> * this bus.
> + * @drv_to_modalias: Called to convert the matching IDs in a
> + * struct device_driver to their corresponding modaliases.
> + * Note that the struct device_driver is expected to belong
> + * to this bus.
> * @pm: Power management operations of this bus, callback the specific
> * device driver's pm-ops.
> * @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU
> @@ -107,6 +111,9 @@ struct bus_type {
> int (*dma_configure)(struct device *dev);
> void (*dma_cleanup)(struct device *dev);
>
> + ssize_t (*drv_to_modalias)(struct device_driver *drv, char *buf,
> + size_t count);
> +
It doesn't fit on a single line ? Up to 100 chars are tolerated as it
would increase readability.
> const struct dev_pm_ops *pm;
>
> const struct iommu_ops *iommu_ops;
> diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c
> index 8dafec7455fbe..651c677c4ab96 100644
> --- a/kernel/module/sysfs.c
> +++ b/kernel/module/sysfs.c
> @@ -5,6 +5,8 @@
> * Copyright (C) 2008 Rusty Russell
> */
>
> +#include <linux/device/bus.h>
> +#include <linux/device/driver.h>
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/fs.h>
> @@ -240,11 +242,64 @@ static inline void add_notes_attrs(struct module *mod, const struct load_info *i
> static inline void remove_notes_attrs(struct module *mod) { }
> #endif /* CONFIG_KALLSYMS */
>
> +/* Track of the buffer and module identity in callbacks when walking the list of
> + * drivers for each bus.
> + */
Comments style.
> +struct modalias_bus_print_state {
> + struct module_kobject *mk;
> + char *buf;
> + size_t count;
> + ssize_t len;
> +};
> +
> +static int print_modalias_for_drv(struct device_driver *drv, void *p)
> +{
> + struct modalias_bus_print_state *s = p;
> + struct module_kobject *mk = s->mk;
> + ssize_t len;
> + /* Skip drivers that do not match this module. */
> + if (mk->mod) {
> + if (mk->mod != drv->owner)
> + return 0;
> + } else if (!mk->kobj.name || !drv->mod_name ||
> + strcmp(mk->kobj.name, drv->mod_name))
> + return 0;
if/else style, see
https://docs.kernel.org/process/coding-style.html#placing-braces-and-spaces
> +
> + if (drv->bus && drv->bus->drv_to_modalias) {
> + len = drv->bus->drv_to_modalias(drv, s->buf + s->len,
> + s->count - s->len);
> + if (len < 0)
> + return len;
> + s->len += len;
> + }
> + return 0;
> +}
> +
> +static int print_modalias_for_bus(struct bus_type *type, void *p)
> +{
> + return bus_for_each_drv(type, NULL, p, print_modalias_for_drv);
> +}
> +
> static ssize_t module_modalias_read(struct file *filp, struct kobject *kobj,
> struct bin_attribute *bin_attr,
> char *buf, loff_t pos, size_t count)
> {
> - return 0;
> + struct module_kobject *mk = container_of(kobj, struct module_kobject,
> + kobj);
Doesn't it fit on one 100 chars line ?
> + struct modalias_bus_print_state state = {mk, buf, count, 0};
> + int error = 0;
Don't initialise vars when it's not needed.
> +
> + if (pos != 0)
> + return -EINVAL;
> +
> + error = bus_for_each(&state, print_modalias_for_bus);
> + if (error)
> + return error;
> +
> + /*
> + * The caller checked the pos and count against our size.
> + */
> + return state.len;
> }
>
> /* Used in kernel/params.c for builtin modules.
On Fri, Dec 02, 2022 at 04:47:42PM -0600, Allen Webb wrote:
> When the modalias attribute is read, invoke a subsystem-specific
> callback for each driver registered by the specific module.
>
> The intent of the new modalias attribute is to expose the
> match-id-based modaliases to userspace for builtin and loaded kernel
> modules.
>
> Signed-off-by: Allen Webb <allenwebb@google.com>
> ---
> include/linux/device/bus.h | 7 +++++
> kernel/module/sysfs.c | 57 +++++++++++++++++++++++++++++++++++++-
> 2 files changed, 63 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h
> index 82a5583437099..cce0bedec63d9 100644
> --- a/include/linux/device/bus.h
> +++ b/include/linux/device/bus.h
> @@ -61,6 +61,10 @@ struct fwnode_handle;
> * this bus.
> * @dma_cleanup: Called to cleanup DMA configuration on a device on
> * this bus.
> + * @drv_to_modalias: Called to convert the matching IDs in a
> + * struct device_driver to their corresponding modaliases.
> + * Note that the struct device_driver is expected to belong
> + * to this bus.
If the driver was not part of this bus, that just wouldn't work at all
so I don't think you need to say this.
And what is the format here? New lines? structures?
> * @pm: Power management operations of this bus, callback the specific
> * device driver's pm-ops.
> * @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU
> @@ -107,6 +111,9 @@ struct bus_type {
> int (*dma_configure)(struct device *dev);
> void (*dma_cleanup)(struct device *dev);
>
> + ssize_t (*drv_to_modalias)(struct device_driver *drv, char *buf,
> + size_t count);
> +
> const struct dev_pm_ops *pm;
>
> const struct iommu_ops *iommu_ops;
> diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c
> index 8dafec7455fbe..651c677c4ab96 100644
> --- a/kernel/module/sysfs.c
> +++ b/kernel/module/sysfs.c
> @@ -5,6 +5,8 @@
> * Copyright (C) 2008 Rusty Russell
> */
>
> +#include <linux/device/bus.h>
> +#include <linux/device/driver.h>
That feels wrong, modules shouldn't care about busses or drivers.
Why can't this all be in the driver core instead?
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/fs.h>
> @@ -240,11 +242,64 @@ static inline void add_notes_attrs(struct module *mod, const struct load_info *i
> static inline void remove_notes_attrs(struct module *mod) { }
> #endif /* CONFIG_KALLSYMS */
>
> +/* Track of the buffer and module identity in callbacks when walking the list of
> + * drivers for each bus.
> + */
> +struct modalias_bus_print_state {
> + struct module_kobject *mk;
> + char *buf;
> + size_t count;
> + ssize_t len;
> +};
> +
> +static int print_modalias_for_drv(struct device_driver *drv, void *p)
> +{
> + struct modalias_bus_print_state *s = p;
> + struct module_kobject *mk = s->mk;
> + ssize_t len;
> + /* Skip drivers that do not match this module. */
Always use checkpatch.pl on your changes before sening them out :(
> + if (mk->mod) {
> + if (mk->mod != drv->owner)
> + return 0;
> + } else if (!mk->kobj.name || !drv->mod_name ||
> + strcmp(mk->kobj.name, drv->mod_name))
> + return 0;
> +
> + if (drv->bus && drv->bus->drv_to_modalias) {
> + len = drv->bus->drv_to_modalias(drv, s->buf + s->len,
> + s->count - s->len);
> + if (len < 0)
> + return len;
> + s->len += len;
> + }
> + return 0;
> +}
> +
> +static int print_modalias_for_bus(struct bus_type *type, void *p)
> +{
> + return bus_for_each_drv(type, NULL, p, print_modalias_for_drv);
> +}
> +
> static ssize_t module_modalias_read(struct file *filp, struct kobject *kobj,
> struct bin_attribute *bin_attr,
> char *buf, loff_t pos, size_t count)
> {
> - return 0;
> + struct module_kobject *mk = container_of(kobj, struct module_kobject,
> + kobj);
> + struct modalias_bus_print_state state = {mk, buf, count, 0};
You allocate this on the stack?
> + int error = 0;
No need to initialize this.
> +
> + if (pos != 0)
> + return -EINVAL;
Why?
> +
> + error = bus_for_each(&state, print_modalias_for_bus);
So for every module attribute, we walk all busses in the system? Why
not the bus that this module has a driver for instead?
thanks,
greg k-h
@@ -61,6 +61,10 @@ struct fwnode_handle;
* this bus.
* @dma_cleanup: Called to cleanup DMA configuration on a device on
* this bus.
+ * @drv_to_modalias: Called to convert the matching IDs in a
+ * struct device_driver to their corresponding modaliases.
+ * Note that the struct device_driver is expected to belong
+ * to this bus.
* @pm: Power management operations of this bus, callback the specific
* device driver's pm-ops.
* @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU
@@ -107,6 +111,9 @@ struct bus_type {
int (*dma_configure)(struct device *dev);
void (*dma_cleanup)(struct device *dev);
+ ssize_t (*drv_to_modalias)(struct device_driver *drv, char *buf,
+ size_t count);
+
const struct dev_pm_ops *pm;
const struct iommu_ops *iommu_ops;
@@ -5,6 +5,8 @@
* Copyright (C) 2008 Rusty Russell
*/
+#include <linux/device/bus.h>
+#include <linux/device/driver.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
@@ -240,11 +242,64 @@ static inline void add_notes_attrs(struct module *mod, const struct load_info *i
static inline void remove_notes_attrs(struct module *mod) { }
#endif /* CONFIG_KALLSYMS */
+/* Track of the buffer and module identity in callbacks when walking the list of
+ * drivers for each bus.
+ */
+struct modalias_bus_print_state {
+ struct module_kobject *mk;
+ char *buf;
+ size_t count;
+ ssize_t len;
+};
+
+static int print_modalias_for_drv(struct device_driver *drv, void *p)
+{
+ struct modalias_bus_print_state *s = p;
+ struct module_kobject *mk = s->mk;
+ ssize_t len;
+ /* Skip drivers that do not match this module. */
+ if (mk->mod) {
+ if (mk->mod != drv->owner)
+ return 0;
+ } else if (!mk->kobj.name || !drv->mod_name ||
+ strcmp(mk->kobj.name, drv->mod_name))
+ return 0;
+
+ if (drv->bus && drv->bus->drv_to_modalias) {
+ len = drv->bus->drv_to_modalias(drv, s->buf + s->len,
+ s->count - s->len);
+ if (len < 0)
+ return len;
+ s->len += len;
+ }
+ return 0;
+}
+
+static int print_modalias_for_bus(struct bus_type *type, void *p)
+{
+ return bus_for_each_drv(type, NULL, p, print_modalias_for_drv);
+}
+
static ssize_t module_modalias_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t pos, size_t count)
{
- return 0;
+ struct module_kobject *mk = container_of(kobj, struct module_kobject,
+ kobj);
+ struct modalias_bus_print_state state = {mk, buf, count, 0};
+ int error = 0;
+
+ if (pos != 0)
+ return -EINVAL;
+
+ error = bus_for_each(&state, print_modalias_for_bus);
+ if (error)
+ return error;
+
+ /*
+ * The caller checked the pos and count against our size.
+ */
+ return state.len;
}
/* Used in kernel/params.c for builtin modules.