Hello Ben, Yes, <tt>a *_safe list traversal method can meet the needs,</tt> <tt>I will modify it and simplify the codes.</tt> <tt>Thanks,</tt> <tt>Tang Junhui</tt> 发件人: "Benjamin Marzinski" <bmarzins@redhat.com> 收件人: tang.junhui@zte.com.cn, 抄送: tang.wenjun3@zte.com.cn, zhang.kai16@zte.com.cn, dm-devel@redhat.com, bart.vanassche@sandisk.com, mwilck@suse.com 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@redhat.com <hr noshade> <tt>On Tue, Dec 27, 2016 at 04:03:26PM +0800, tang.junhui@zte.com.cn wrote: > From: tang.junhui <tang.junhui@zte.com.cn> > > 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@zte.com.cn> > --- > 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 > -- dm-devel mailing list dm-devel@redhat.com </tt><a href="https://www.redhat.com/mailman/listinfo/dm-devel"><tt>https://www.redhat.com/mailman/listinfo/dm-devel</tt></a><tt> </tt>