/* * llc_if.c - Defines LLC interface to upper layer * * Copyright (c) 1997 by Procom Technology, Inc. * 2001-2003 by Arnaldo Carvalho de Melo * * This program can be redistributed or modified under the terms of the * GNU General Public License as published by the Free Software Foundation. * This program is distributed without any warranty or implied warranty * of merchantability or fitness for a particular purpose. * * See the GNU General Public License for more details. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include /** * llc_build_and_send_pkt - Connection data sending for upper layers. * @sk: connection * @skb: packet to send * * This function is called when upper layer wants to send data using * connection oriented communication mode. During sending data, connection * will be locked and received frames and expired timers will be queued. * Returns 0 for success, -ECONNABORTED when the connection already * closed and -EBUSY when sending data is not permitted in this state or * LLC has send an I pdu with p bit set to 1 and is waiting for it's * response. */ int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb) { struct llc_conn_state_ev *ev; int rc = -ECONNABORTED; struct llc_sock *llc = llc_sk(sk); if (unlikely(llc->state == LLC_CONN_STATE_ADM)) goto out; rc = -EBUSY; if (unlikely(llc_data_accept_state(llc->state) || /* data_conn_refuse */ llc->p_flag)) { llc->failed_data_req = 1; goto out; } ev = llc_conn_ev(skb); ev->type = LLC_CONN_EV_TYPE_PRIM; ev->prim = LLC_DATA_PRIM; ev->prim_type = LLC_PRIM_TYPE_REQ; skb->dev = llc->dev; rc = llc_conn_state_process(sk, skb); out: return rc; } /** * llc_establish_connection - Called by upper layer to establish a conn * @sk: connection * @lmac: local mac address * @dmac: destination mac address * @dsap: destination sap * * Upper layer calls this to establish an LLC connection with a remote * machine. This function packages a proper event and sends it connection * component state machine. Success or failure of connection * establishment will inform to upper layer via calling it's confirm * function and passing proper information. */ int llc_establish_connection(struct sock *sk, u8 *lmac, u8 *dmac, u8 dsap) { int rc = -EISCONN; struct llc_addr laddr, daddr; struct sk_buff *skb; struct llc_sock *llc = llc_sk(sk); struct sock *existing; laddr.lsap = llc->sap->laddr.lsap; daddr.lsap = dsap; memcpy(daddr.mac, dmac, sizeof(daddr.mac)); memcpy(laddr.mac, lmac, sizeof(laddr.mac)); existing = llc_lookup_established(llc->sap, &daddr, &laddr); if (existing) { if (existing->sk_state == TCP_ESTABLISHED) { sk = existing; goto out_put; } else sock_put(existing); } sock_hold(sk); rc = -ENOMEM; skb = alloc_skb(0, GFP_ATOMIC); if (skb) { struct llc_conn_state_ev *ev = llc_conn_ev(skb); ev->type = LLC_CONN_EV_TYPE_PRIM; ev->prim = LLC_CONN_PRIM; ev->prim_type = LLC_PRIM_TYPE_REQ; skb_set_owner_w(skb, sk); rc = llc_conn_state_process(sk, skb); } out_put: sock_put(sk); return rc; } /** * llc_send_disc - Called by upper layer to close a connection * @sk: connection to be closed * * Upper layer calls this when it wants to close an established LLC * connection with a remote machine. This function packages a proper event * and sends it to connection component state machine. Returns 0 for * success, 1 otherwise. */ int llc_send_disc(struct sock *sk) { u16 rc = 1; struct llc_conn_state_ev *ev; struct sk_buff *skb; sock_hold(sk); if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED || llc_sk(sk)->state == LLC_CONN_STATE_ADM || llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC) goto out; /* * Postpone unassigning the connection from its SAP and returning the * connection until all ACTIONs have been completely executed */ skb = alloc_skb(0, GFP_ATOMIC); if (!skb) goto out; skb_set_owner_w(skb, sk); sk->sk_state = TCP_CLOSING; ev = llc_conn_ev(skb); ev->type = LLC_CONN_EV_TYPE_PRIM; ev->prim = LLC_DISC_PRIM; ev->prim_type = LLC_PRIM_TYPE_REQ; rc = llc_conn_state_process(sk, skb); out: sock_put(sk); return rc; } selected='selected'>unified
authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /tools/perf/tests/backward-ring-buffer.c
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'tools/perf/tests/backward-ring-buffer.c')