lkml.org 
[lkml]   [2022]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH bpf-next v2 25/28] bpf/hid: Add a flag to add the program at the beginning of the list
    Date
    When tracing the incoming events, if a bpf program is already loaded,
    the next bpf program will see the potentially changed data.

    Add a flag to BPF_LINK_CREATE that allows to chose the position of the
    inserted program: at the beginning or at the end.

    This way, we can have a tracing program that compare the raw event from
    the device and the transformed stream from all the other bpf programs.

    Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

    ---

    new in v2
    ---
    include/uapi/linux/bpf.h | 10 ++++++++++
    kernel/bpf/hid.c | 11 +++++++----
    2 files changed, 17 insertions(+), 4 deletions(-)

    diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
    index 417cf1c31579..23ebe5e96d69 100644
    --- a/include/uapi/linux/bpf.h
    +++ b/include/uapi/linux/bpf.h
    @@ -1123,6 +1123,16 @@ enum bpf_link_type {
    */
    #define BPF_F_XDP_HAS_FRAGS (1U << 5)

    +/* HID flag used in BPF_LINK_CREATE command
    + *
    + * NONE(default): The bpf program will be added at the tail of the list
    + * of existing bpf program for this type.
    + *
    + * BPF_F_INSERT_HEAD: The bpf program will be added at the beginning
    + * of the list of existing bpf program for this type..
    + */
    +#define BPF_F_INSERT_HEAD (1U << 0)
    +
    /* When BPF ldimm64's insn[0].src_reg != 0 then this can have
    * the following extensions:
    *
    diff --git a/kernel/bpf/hid.c b/kernel/bpf/hid.c
    index b3dc1cd37a3e..141eb4169079 100644
    --- a/kernel/bpf/hid.c
    +++ b/kernel/bpf/hid.c
    @@ -416,7 +416,7 @@ static int bpf_hid_max_progs(enum bpf_hid_attach_type type)
    }

    static int bpf_hid_link_attach(struct hid_device *hdev, struct bpf_link *link,
    - enum bpf_hid_attach_type type)
    + enum bpf_hid_attach_type type, u32 flags)
    {
    struct bpf_hid_link *hid_link =
    container_of(link, struct bpf_hid_link, link);
    @@ -443,7 +443,10 @@ static int bpf_hid_link_attach(struct hid_device *hdev, struct bpf_link *link,
    goto out_unlock;
    }

    - list_add_tail(&hid_link->node, &hdev->bpf.links[type]);
    + if (flags & BPF_F_INSERT_HEAD)
    + list_add(&hid_link->node, &hdev->bpf.links[type]);
    + else
    + list_add_tail(&hid_link->node, &hdev->bpf.links[type]);

    fill_prog_array(hdev, type, run_array);
    run_array = rcu_replace_pointer(hdev->bpf.run_array[type], run_array,
    @@ -467,7 +470,7 @@ int bpf_hid_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
    struct hid_device *hdev;
    int err;

    - if (attr->link_create.flags || !hid_hooks.hdev_from_fd)
    + if ((attr->link_create.flags & ~BPF_F_INSERT_HEAD) || !hid_hooks.hdev_from_fd)
    return -EINVAL;

    type = attr->link_create.attach_type;
    @@ -495,7 +498,7 @@ int bpf_hid_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
    return err;
    }

    - err = bpf_hid_link_attach(hdev, &hid_link->link, hid_type);
    + err = bpf_hid_link_attach(hdev, &hid_link->link, hid_type, attr->link_create.flags);
    if (err) {
    bpf_link_cleanup(&link_primer);
    return err;
    --
    2.35.1
    \
     
     \ /
      Last update: 2022-03-04 18:37    [W:4.216 / U:0.048 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site