On Mon, 2006-27-02 at 03:31 -0500, Shailabh Nagar wrote:
> +#define TASKSTATS_LISTEN_GROUP 0x1
You do multicast to this group - does this mean there could be multiple
listeners subscribed for this event?
How does this correlate to TASKSTATS_CMD_LISTEN/IGNORE?
Typically, an equivalent of listen is when the first user space app
joins this group; and when it leaves, you have equivalency to ignore.
Unless i misunderstood what you are trying to do with this.
> +
> +/*
> + * Commands sent from userspace
> + * Not versioned. New commands should only be inserted at the enum's end
> + */
> +
> +enum {
> + TASKSTATS_CMD_UNSPEC, /* Reserved */
> + TASKSTATS_CMD_NONE, /* Not a valid cmd to send
> + * Marks data sent on task/tgid exit */
you should call it NONE just because it is unidirectional
(kernel->user). You should check in the kernel if someone sends it from
user space and/or set a command flag etc.
> + TASKSTATS_CMD_LISTEN, /* Start listening */
> + TASKSTATS_CMD_IGNORE, /* Stop listening */
> + TASKSTATS_CMD_PID, /* Send stats for a pid */
> + TASKSTATS_CMD_TGID, /* Send stats for a tgid */
> +};
> +
> +/* Parameters for commands
> + * New parameters should only be inserted at the struct's end
> + */
> +
> +struct taskstats_cmd_param {
> + union {
> + pid_t pid;
> + pid_t tgid;
> + } id;
> +};
> +
> +/*
> + * Reply sent from kernel
> + * Version number affects size/format of struct taskstats only
> + */
> +
> +struct taskstats_reply {
> + enum outtype {
> + TASKSTATS_REPLY_NONE = 1, /* Control cmd response */
> + TASKSTATS_REPLY_PID, /* per-pid data cmd response*/
> + TASKSTATS_REPLY_TGID, /* per-tgid data cmd response*/
> + TASKSTATS_REPLY_EXIT_PID, /* Exiting task's stats */
> + TASKSTATS_REPLY_EXIT_TGID, /* Exiting tgid's stats
> + * (sent on each tid's exit) */
> + } outtype;
> + __u32 version;
> + __u32 err;
> + struct taskstats stats; /* Invalid if err != 0 */
> +};
> +
Make sure you have proper alignment of above for things like x86-64
> +/* NETLINK_GENERIC related info */
> +
> +#define TASKSTATS_GENL_NAME "TASKSTATS"
> +#define TASKSTATS_GENL_VERSION 0x1
> +/* Following must be > NLMSG_MIN_TYPE */
> +#define TASKSTATS_GENL_ID 0x123
You do not check whether you got this id on registration or not.
It is not guaranteed for you.
cheers,
jamal
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