cxgb3i: convert cdev->l2opt to use rcu to prevent NULL dereference
commit e48f129c2f200dde8899f6ea5c6e7173674fc482 upstream.
This oops was reported recently:
d:mon> e
cpu 0xd: Vector: 300 (Data Access) at [c0000000fd4c7120]
pc: d00000000076f194: .t3_l2t_get+0x44/0x524 [cxgb3]
lr: d000000000b02108: .init_act_open+0x150/0x3d4 [cxgb3i]
sp: c0000000fd4c73a0
msr: 8000000000009032
dar: 0
dsisr: 40000000
current = 0xc0000000fd640d40
paca = 0xc00000000054ff80
pid = 5085, comm = iscsid
d:mon> t
[c0000000fd4c7450] d000000000b02108 .init_act_open+0x150/0x3d4 [cxgb3i]
[c0000000fd4c7500] d000000000e45378 .cxgbi_ep_connect+0x784/0x8e8 [libcxgbi]
[c0000000fd4c7650] d000000000db33f0 .iscsi_if_rx+0x71c/0xb18
[scsi_transport_iscsi2]
[c0000000fd4c7740] c000000000370c9c .netlink_data_ready+0x40/0xa4
[c0000000fd4c77c0] c00000000036f010 .netlink_sendskb+0x4c/0x9c
[c0000000fd4c7850] c000000000370c18 .netlink_sendmsg+0x358/0x39c
[c0000000fd4c7950] c00000000033be24 .sock_sendmsg+0x114/0x1b8
[c0000000fd4c7b50] c00000000033d208 .sys_sendmsg+0x218/0x2ac
[c0000000fd4c7d70] c00000000033f55c .sys_socketcall+0x228/0x27c
[c0000000fd4c7e30] c0000000000086a4 syscall_exit+0x0/0x40
diff --git a/drivers/net/cxgb3/l2t.h b/drivers/net/cxgb3/l2t.h
index fd3eb07..c4dd066 100644
--- a/drivers/net/cxgb3/l2t.h
+++ b/drivers/net/cxgb3/l2t.h
@@ -76,6 +76,7 @@
atomic_t nfree; /* number of free entries */
rwlock_t lock;
struct l2t_entry l2tab[0];
+ struct rcu_head rcu_head; /* to handle rcu cleanup */
};
typedef void (*arp_failure_handler_func)(struct t3cdev * dev,
@@ -99,7 +100,7 @@
/*
* Getting to the L2 data from an offload device.
*/
-#define L2DATA(dev) ((dev)->l2opt)
+#define L2DATA(cdev) (rcu_dereference((cdev)->l2opt))
#define W_TCB_L2T_IX 0
#define S_TCB_L2T_IX 7
@@ -126,15 +127,22 @@
return t3_l2t_send_slow(dev, skb, e);
}
-static inline void l2t_release(struct l2t_data *d, struct l2t_entry *e)
+static inline void l2t_release(struct t3cdev *t, struct l2t_entry *e)
{
- if (atomic_dec_and_test(&e->refcnt))
+ struct l2t_data *d;
+
+ rcu_read_lock();
+ d = L2DATA(t);
+
+ if (atomic_dec_and_test(&e->refcnt) && d)
t3_l2e_free(d, e);
+
+ rcu_read_unlock();
}
static inline void l2t_hold(struct l2t_data *d, struct l2t_entry *e)
{
- if (atomic_add_return(1, &e->refcnt) == 1) /* 0 -> 1 transition */
+ if (d && atomic_add_return(1, &e->refcnt) == 1) /* 0 -> 1 transition */
atomic_dec(&d->nfree);
}