xfrm: remove useless hash_resize_mutex locks (0244790c) · Commits · 戴 / test

In xfrm_state.c, hash_resize_mutex is defined as a local variable and only used in xfrm_hash_resize() which is declared as a work handler of xfrm.state_hash_work. But when the xfrm.state_hash_work work is put in the global workqueue(system_wq) with schedule_work(), the work will be really inserted in the global workqueue if it was not already queued, otherwise, it is still left in the same position on the the global workqueue. This means the xfrm_hash_resize() work handler is only executed once at any time no matter how many times its work is scheduled, that is, xfrm_hash_resize() is not called concurrently at all, so hash_resize_mutex is redundant for us. Cc: Christophe Gouault <christophe.gouault@6wind.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by:

Ying Xue <ying.xue@windriver.com> Acked-by:

David S. Miller <davem@davemloft.net> Signed-off-by:

Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_state.c

+3 −10

Original line number	Diff line number	Diff line
		@@ -97,8 +97,6 @@ static unsigned long xfrm_hash_new_size(unsigned int state_hmask)
		return ((state_hmask + 1) << 1) * sizeof(struct hlist_head);
		}

		static DEFINE_MUTEX(hash_resize_mutex);

		static void xfrm_hash_resize(struct work_struct *work)
		{
		struct net *net = container_of(work, struct net, xfrm.state_hash_work);
		@@ -107,22 +105,20 @@ static void xfrm_hash_resize(struct work_struct *work)
		unsigned int nhashmask, ohashmask;
		int i;

		mutex_lock(&hash_resize_mutex);

		nsize = xfrm_hash_new_size(net->xfrm.state_hmask);
		ndst = xfrm_hash_alloc(nsize);
		if (!ndst)
		goto out_unlock;
		return;
		nsrc = xfrm_hash_alloc(nsize);
		if (!nsrc) {
		xfrm_hash_free(ndst, nsize);
		goto out_unlock;
		return;
		}
		nspi = xfrm_hash_alloc(nsize);
		if (!nspi) {
		xfrm_hash_free(ndst, nsize);
		xfrm_hash_free(nsrc, nsize);
		goto out_unlock;
		return;
		}

		spin_lock_bh(&net->xfrm.xfrm_state_lock);
		@@ -148,9 +144,6 @@ static void xfrm_hash_resize(struct work_struct *work)
		xfrm_hash_free(odst, osize);
		xfrm_hash_free(osrc, osize);
		xfrm_hash_free(ospi, osize);

		out_unlock:
		mutex_unlock(&hash_resize_mutex);
		}

		static DEFINE_SPINLOCK(xfrm_state_afinfo_lock);

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