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Commit 5beb5c90 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

rhashtable: use cond_resched() 



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: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 061c1a6e

lib/rhashtable.c

+4 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/log2.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <linux/mm.h>
@@ -412,6 +413,7 @@ int rhashtable_expand(struct rhashtable *ht) 
			}

		}

		unlock_buckets(new_tbl, old_tbl, new_hash);

		cond_resched();

	}



	/* Unzip interleaved hash chains */
@@ -435,6 +437,7 @@ int rhashtable_expand(struct rhashtable *ht) 
				complete = false;



			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]);



		unlock_buckets(new_tbl, tbl, new_hash);

		cond_resched();

	}



	/* Publish the new, valid hash table */