Yes, a *_safe list traversal method can meet the needs,
I will modify it and simplify the codes.
Thanks,
Tang Junhui
发件人: "Benjamin Marzinski" <bmarzins@xxxxxxxxxx>
收件人: tang.junhui@xxxxxxxxxx,
抄送: tang.wenjun3@xxxxxxxxxx, zhang.kai16@xxxxxxxxxx, dm-devel@xxxxxxxxxx, bart.vanassche@xxxxxxxxxxx, mwilck@xxxxxxxx
日期: 2017/01/04 08:39
主题: Re: [dm-devel] [PATCH 09/12] multipathd: merge uevents before proccessing
发件人: dm-devel-bounces@xxxxxxxxxx
On Tue, Dec 27, 2016 at 04:03:26PM +0800, tang.junhui@xxxxxxxxxx wrote:
> From: tang.junhui <tang.junhui@xxxxxxxxxx>
>
> These uevents are going to be merged:
> 1) uevents come from paths and
> 2) uevents type is same and
> 3) uevents type is addition or deletion and
> 4) uevents wwid is same.
This is just a nit, and I might be missing something subtle here, but it
seems like instead of adding list_for_some_entry_reverse, and then
breaking the abstraction to manually get previous entries, you could
have just added list_for_some_entry_reverse_safe in your earlier patch,
and hid the work of traversing a list while removing elements behind the
well understood abstraction of a *_safe list traversal method.
-Ben
>
> Change-Id: I05ee057391c092aa0c5f989b7a4f9cb550bb4d98
> Signed-off-by: tang.junhui <tang.junhui@xxxxxxxxxx>
> ---
> libmultipath/uevent.c | 125 +++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 114 insertions(+), 11 deletions(-)
>
> diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
> index b0b05e9..114068c 100644
> --- a/libmultipath/uevent.c
> +++ b/libmultipath/uevent.c
> @@ -85,6 +85,20 @@ struct uevent * alloc_uevent (void)
> return uev;
> }
>
> +void
> +uevq_cleanup(struct list_head *tmpq)
> +{
> + struct uevent *uev, *tmp;
> +
> + list_for_each_entry_safe(uev, tmp, tmpq, node) {
> + list_del_init(&uev->node);
> +
> + if (uev->udev)
> + udev_device_unref(uev->udev);
> + FREE(uev);
> + }
> +}
> +
> bool
> uevent_can_discard(char *devpath, char *kernel)
> {
> @@ -125,6 +139,103 @@ uevent_can_discard(char *devpath, char *kernel)
> return false;
> }
>
> +bool
> +merge_need_stop(struct uevent *earlier, struct uevent *later)
> +{
> + /*
> + * dm uevent do not try to merge with left uevents
> + */
> + if (!strncmp(later->kernel, "dm-", 3))
> + return true;
> +
> + /*
> + * we can not make a jugement without wwid,
> + * so it is sensible to stop merging
> + */
> + if (!earlier->wwid || !later->wwid)
> + return true;
> + /*
> + * uevents merging stoped
> + * when we meet an opposite action uevent from the same LUN to AVOID
> + * "add path1 |remove path1 |add path2 |remove path2 |add path3"
> + * to merge as "remove path1, path2" and "add path1, path2, path3"
> + * OR
> + * "remove path1 |add path1 |remove path2 |add path2 |remove path3"
> + * to merge as "add path1, path2" and "remove path1, path2, path3"
> + * SO
> + * when we meet a non-change uevent from the same LUN
> + * with the same wwid and different action
> + * it would be better to stop merging.
> + */
> + if (!strcmp(earlier->wwid, later->wwid) &&
> + strcmp(earlier->action, later->action) &&
> + strcmp(earlier->action, "change") &&
> + strcmp(later->action, "change"))
> + return true;
> +
> + return false;
> +}
> +
> +bool
> +uevent_can_merge(struct uevent *earlier, struct uevent *later)
> +{
> + /* merge paths uevents
> + * whose wwids exsit and are same
> + * and actions are same,
> + * and actions are addition or deletion
> + */
> + if (earlier->wwid && later->wwid &&
> + !strcmp(earlier->wwid, later->wwid) &&
> + !strcmp(earlier->action, later->action) &&
> + strncmp(earlier->action, "change", 6) &&
> + strncmp(earlier->kernel, "dm-", 3)) {
> + return true;
> + }
> +
> + return false;
> +}
> +
> +void
> +uevent_merge(struct uevent *later, struct list_head *tmpq)
> +{
> + struct uevent *earlier, *temp;
> + /*
> + * compare the uevent with earlier uevents
> + */
> + list_for_some_entry_reverse(earlier, &later->node, tmpq, node) {
> +next_earlier_node:
> + if (merge_need_stop(earlier, later))
> + break;
> + /*
> + * try to merge earlier uevents to the later uevent
> + */
> + if (uevent_can_merge(earlier, later)) {
> + condlog(3, "merged uevent: %s-%s-%s with uevent: %s-%s-%s",
> + earlier->action, earlier->kernel, earlier->wwid,
> + later->action, later->kernel, later->wwid);
> + temp = earlier;
> +
> + earlier = list_entry(earlier->node.prev, typeof(struct uevent), node);
> + list_move(&temp->node, &later->merge_node);
> +
> + if (earlier == list_entry(tmpq, typeof(struct uevent), node))
> + break;
> + else
> + goto next_earlier_node;
> + }
> + }
> +}
> +
> +void
> +merge_uevq(struct list_head *tmpq)
> +{
> + struct uevent *later;
> +
> + list_for_each_entry_reverse(later, tmpq, node) {
> + uevent_merge(later, tmpq);
> + }
> +}
> +
> void
> service_uevq(struct list_head *tmpq)
> {
> @@ -136,6 +247,8 @@ service_uevq(struct list_head *tmpq)
> if (my_uev_trigger && my_uev_trigger(uev, my_trigger_data))
> condlog(0, "uevent trigger error");
>
> + uevq_cleanup(&uev->merge_node);
> +
> if (uev->udev)
> udev_device_unref(uev->udev);
> FREE(uev);
> @@ -150,17 +263,6 @@ static void uevent_cleanup(void *arg)
> udev_unref(udev);
> }
>
> -void
> -uevq_cleanup(struct list_head *tmpq)
> -{
> - struct uevent *uev, *tmp;
> -
> - list_for_each_entry_safe(uev, tmp, tmpq, node) {
> - list_del_init(&uev->node);
> - FREE(uev);
> - }
> -}
> -
> /*
> * Service the uevent queue.
> */
> @@ -189,6 +291,7 @@ int uevent_dispatch(int (*uev_trigger)(struct uevent *, void * trigger_data),
> pthread_mutex_unlock(uevq_lockp);
> if (!my_uev_trigger)
> break;
> + merge_uevq(&uevq_tmp);
> service_uevq(&uevq_tmp);
> }
> condlog(3, "Terminating uev service queue");
> --
> 2.8.1.windows.1
>
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