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Commit 7a474c36 authored by Florian Westphal's avatar Florian Westphal Committed by Steffen Klassert
Browse files

xfrm: policy: increment xfrm_hash_generation on hash rebuild 



Hash rebuild will re-set all the inexact entries, then re-insert them.
Lookups that can occur in parallel will therefore not find any policies.

This was safe when lookups were still guarded by rwlock.
After rcu-ification, lookups check the hash_generation seqcount to detect
when a hash resize takes place.  Hash rebuild missed the needed increment.

Hash resizes and hash rebuilds cannot occur in parallel (both acquire
hash_resize_mutex), so just increment xfrm_hash_generation, like resize.

Fixes: a7c44247 ("xfrm: policy: make xfrm_policy_lookup_bytype lockless")
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 355b00d1

net/xfrm/xfrm_policy.c

+2 −0
Original line number Diff line number Diff line
@@ -1235,6 +1235,7 @@ static void xfrm_hash_rebuild(struct work_struct *work) 
	} while (read_seqretry(&net->xfrm.policy_hthresh.lock, seq));



	spin_lock_bh(&net->xfrm.xfrm_policy_lock);

	write_seqcount_begin(&xfrm_policy_hash_generation);



	/* make sure that we can insert the indirect policies again before

	 * we start with destructive action.
@@ -1334,6 +1335,7 @@ static void xfrm_hash_rebuild(struct work_struct *work) 


out_unlock:

	__xfrm_policy_inexact_flush(net);

	write_seqcount_end(&xfrm_policy_hash_generation);

	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);



	mutex_unlock(&hash_resize_mutex);