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HID: bpf: protect HID-BPF prog_list access by a SRCU

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We want to add sleepable callbacks for hid_hw_raw_request() and
hid_hw_output_report(), but we can not use a plain RCU for those.

Prepare for a SRCU so we can extend HID-BPF.

This changes a little bit how hid_bpf_device_init() behaves, as it may
now fail, so there is a tiny hid-core.c change to accommodate for this.

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-3-cfd60fb6c79f@kernel.org
Acked-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
This commit is contained in:
Benjamin Tissoires 2024-06-26 15:46:24 +02:00
parent 67eccf151d
commit 6cd735f0e5
4 changed files with 18 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/hid/bpf/hid_bpf_dispatch.c
View File

@ -506,13 +506,17 @@ void hid_bpf_destroy_device(struct hid_device *hdev)
hdev->bpf.destroyed = true;
__hid_bpf_ops_destroy_device(hdev);
synchronize_srcu(&hdev->bpf.srcu);
cleanup_srcu_struct(&hdev->bpf.srcu);
}
EXPORT_SYMBOL_GPL(hid_bpf_destroy_device);
void hid_bpf_device_init(struct hid_device *hdev)
int hid_bpf_device_init(struct hid_device *hdev)
{
INIT_LIST_HEAD(&hdev->bpf.prog_list);
mutex_init(&hdev->bpf.prog_list_lock);
return init_srcu_struct(&hdev->bpf.srcu);
}
EXPORT_SYMBOL_GPL(hid_bpf_device_init);

2
drivers/hid/bpf/hid_bpf_struct_ops.c
View File

@ -214,6 +214,7 @@ static int hid_bpf_reg(void *kdata)
list_add_rcu(&ops->list, &hdev->bpf.prog_list);
else
list_add_tail_rcu(&ops->list, &hdev->bpf.prog_list);
synchronize_srcu(&hdev->bpf.srcu);
out_unlock:
mutex_unlock(&hdev->bpf.prog_list_lock);
@ -244,6 +245,7 @@ static void hid_bpf_unreg(void *kdata)
mutex_lock(&hdev->bpf.prog_list_lock);
list_del_rcu(&ops->list);
synchronize_srcu(&hdev->bpf.srcu);
reconnect = hdev->bpf.rdesc_ops == ops;
if (reconnect)

8
drivers/hid/hid-core.c
View File

@ -2875,9 +2875,15 @@ struct hid_device *hid_allocate_device(void)
mutex_init(&hdev->ll_open_lock);
kref_init(&hdev->ref);
hid_bpf_device_init(hdev);
ret = hid_bpf_device_init(hdev);
if (ret)
goto out_err;
return hdev;
out_err:
hid_destroy_device(hdev);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(hid_allocate_device);

6
include/linux/hid_bpf.h
View File

@ -5,6 +5,7 @@
#include <linux/bpf.h>
#include <linux/mutex.h>
#include <linux/srcu.h>
#include <uapi/linux/hid.h>
struct hid_device;
@ -145,6 +146,7 @@ struct hid_bpf {
struct hid_bpf_ops *rdesc_ops;
struct list_head prog_list;
struct mutex prog_list_lock; /* protects prog_list update */
struct srcu_struct srcu; /* protects prog_list read-only access */
};
#ifdef CONFIG_HID_BPF
@ -153,7 +155,7 @@ u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type t
int hid_bpf_connect_device(struct hid_device *hdev);
void hid_bpf_disconnect_device(struct hid_device *hdev);
void hid_bpf_destroy_device(struct hid_device *hid);
void hid_bpf_device_init(struct hid_device *hid);
int hid_bpf_device_init(struct hid_device *hid);
u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size);
#else /* CONFIG_HID_BPF */
static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
@ -162,7 +164,7 @@ static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid
static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
static inline void hid_bpf_destroy_device(struct hid_device *hid) {}
static inline void hid_bpf_device_init(struct hid_device *hid) {}
static inline int hid_bpf_device_init(struct hid_device *hid) { return 0; }
#define call_hid_bpf_rdesc_fixup(_hdev, _rdesc, _size) \
((u8 *)kmemdup(_rdesc, *(_size), GFP_KERNEL))