diff options
| author | Florian Westphal <fw@strlen.de> | 2016-08-09 12:16:05 +0200 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2016-08-10 11:23:23 +0200 |
| commit | 02efdff7e209859c2755ebe93b3bd0e3d40123ab (patch) | |
| tree | d7008910ee8bc52787e18eda78733c31ea44ba39 /net/xfrm | |
| parent | xfrm: state: use hlist_for_each_entry_rcu helper (diff) | |
| download | linux-02efdff7e209859c2755ebe93b3bd0e3d40123ab.tar.xz linux-02efdff7e209859c2755ebe93b3bd0e3d40123ab.zip | |
xfrm: state: use atomic_inc_not_zero to increment refcount
Once xfrm_state_lookup_byaddr no longer acquires the state lock another
cpu might be freeing the state entry at the same time.
To detect this we use atomic_inc_not_zero, we then signal -EAGAIN to
caller in case our result was stale.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/xfrm')
| -rw-r--r-- | net/xfrm/xfrm_state.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 904ab4d4ac05..84c1db6254d5 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -37,6 +37,11 @@ static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024; +static inline bool xfrm_state_hold_rcu(struct xfrm_state __rcu *x) +{ + return atomic_inc_not_zero(&x->refcnt); +} + static inline unsigned int xfrm_dst_hash(struct net *net, const xfrm_address_t *daddr, const xfrm_address_t *saddr, @@ -668,7 +673,8 @@ static struct xfrm_state *__xfrm_state_lookup(struct net *net, u32 mark, if ((mark & x->mark.m) != x->mark.v) continue; - xfrm_state_hold(x); + if (!xfrm_state_hold_rcu(x)) + continue; return x; } @@ -692,7 +698,8 @@ static struct xfrm_state *__xfrm_state_lookup_byaddr(struct net *net, u32 mark, if ((mark & x->mark.m) != x->mark.v) continue; - xfrm_state_hold(x); + if (!xfrm_state_hold_rcu(x)) + continue; return x; } @@ -871,10 +878,14 @@ found: } } out: - if (x) - xfrm_state_hold(x); - else + if (x) { + if (!xfrm_state_hold_rcu(x)) { + *err = -EAGAIN; + x = NULL; + } + } else { *err = acquire_in_progress ? -EAGAIN : error; + } spin_unlock_bh(&net->xfrm.xfrm_state_lock); if (to_put) xfrm_state_put(to_put); |