On Fri, Dec 1, 2017 at 3:29 PM, Tom Herbert <t...@quantonium.net> wrote: > On Fri, Dec 1, 2017 at 2:18 PM, Herbert Xu <herb...@gondor.apana.org.au> > wrote: >> On Thu, Nov 30, 2017 at 04:03:01PM -0800, Tom Herbert wrote: >>> Remove the code that resets the walker table. The walker table should >>> only be initialized in the walk init function or when a future table is >>> encountered. If the walker table is NULL this is the indication that >>> the walk has completed and this information can be used to break a >>> multi-call walk in the table (e.g. successive calls to nelink_dump >>> that are dumping elements of an rhashtable). >>> >>> This also allows us to change rhashtable_walk_start to return void >>> since the only error it was returning was -EAGAIN for a table change. >>> This patch changes all the callers of rhashtable_walk_start to expect >>> void which eliminates logic needed to check the return value for a >>> rare condition. Note that -EAGAIN will be returned in a call >>> to rhashtable_walk_next which seems to always follow the start >>> of the walk so there should be no behavioral change in doing this. >>> >>> Signed-off-by: Tom Herbert <t...@quantonium.net> >> >> Doesn't this mean that if a walk encounters a rehash you may end up >> missing half or more of the hash table? >> > Because of tbl->rehash < tbl->size conditions in walk stop? How about > we add a flag to iter that indicates table needs a reset and set it > along with setting walker.tbl to NULL? On the next walk start do the > reload when walker.tbl is NULL and flag is set. In this case walk > start would automatically set walker.tbl which is already done by > nearly all callers already in that they ignore -EAGAIN returned from > start walk. > Herbert,
Looking at this some more, I am wondering if the walkers list is necessary. When a rehash table is done, the new table is assigned to ht->tbl and walker->tbl is cleared for all walkers. In walk start the walker tbl is checked and if it's NULL ht->tbl is loaded. Assuming that -EAGAIN isn't interesting to callers here, it seems like we could just get iter->walker.tbl in each call to walk start and not need to maintain the walkers list at all. Am I missing something? Tom > Thanks, > Tom > >> Cheers, >> -- >> Email: Herbert Xu <herb...@gondor.apana.org.au> >> Home Page: http://gondor.apana.org.au/~herbert/ >> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
