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rhashtable: use cond_resched()

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If a hash table has 128 slots and 16384 elems, expand to 256 slots
takes more than one second. For larger sets, a soft lockup is detected.

Holding cpu for that long, even in a work queue is a show stopper
for non preemptable kernels.

cond_resched() at strategic points to allow process scheduler
to reschedule us.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-02-26 07:20:34 -08:00 • committed by David S. Miller
commit 5beb5c90c1
1 changed files with 4 additions and 0 deletions
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4
lib/rhashtable.c
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@ -17,6 +17,7 @@
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/log2.h> #include <linux/log2.h>
#include <linux/sched.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/mm.h> #include <linux/mm.h>
@ -412,6 +413,7 @@ int rhashtable_expand(struct rhashtable *ht)
} }
} }
unlock_buckets(new_tbl, old_tbl, new_hash); unlock_buckets(new_tbl, old_tbl, new_hash);
cond_resched();
} }
/* Unzip interleaved hash chains */ /* Unzip interleaved hash chains */
@ -435,6 +437,7 @@ int rhashtable_expand(struct rhashtable *ht)
complete = false; complete = false;
unlock_buckets(new_tbl, old_tbl, old_hash); unlock_buckets(new_tbl, old_tbl, old_hash);
cond_resched();
} }
} }
@ -493,6 +496,7 @@ int rhashtable_shrink(struct rhashtable *ht)
tbl->buckets[new_hash + new_tbl->size]); tbl->buckets[new_hash + new_tbl->size]);
unlock_buckets(new_tbl, tbl, new_hash); unlock_buckets(new_tbl, tbl, new_hash);
cond_resched();
} }
/* Publish the new, valid hash table */ /* Publish the new, valid hash table */