/* * w1_netlink.h * * Copyright (c) 2003 Evgeniy Polyakov * * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #ifndef __W1_NETLINK_H #define __W1_NETLINK_H #include #include #include "w1.h" /** * enum w1_cn_msg_flags - bitfield flags for struct cn_msg.flags * * @W1_CN_BUNDLE: Request bundling replies into fewer messagse. Be prepared * to handle multiple struct cn_msg, struct w1_netlink_msg, and * struct w1_netlink_cmd in one packet. */ enum w1_cn_msg_flags { W1_CN_BUNDLE = 1, }; /** * enum w1_netlink_message_types - message type * * @W1_SLAVE_ADD: notification that a slave device was added * @W1_SLAVE_REMOVE: notification that a slave device was removed * @W1_MASTER_ADD: notification that a new bus master was added * @W1_MASTER_REMOVE: notification that a bus masterwas removed * @W1_MASTER_CMD: initiate operations on a specific master * @W1_SLAVE_CMD: sends reset, selects the slave, then does a read/write/touch * operation * @W1_LIST_MASTERS: used to determine the bus master identifiers */ enum w1_netlink_message_types { W1_SLAVE_ADD = 0, W1_SLAVE_REMOVE, W1_MASTER_ADD, W1_MASTER_REMOVE, W1_MASTER_CMD, W1_SLAVE_CMD, W1_LIST_MASTERS, }; /** * struct w1_netlink_msg - holds w1 message type, id, and result * * @type: one of enum w1_netlink_message_types * @status: kernel feedback for success 0 or errno failure value * @len: length of data following w1_netlink_msg * @id: union holding master bus id (msg.id) and slave device id (id[8]). * @data: start address of any following data * * The base message structure for w1 messages over netlink. * The netlink connector data sequence is, struct nlmsghdr, struct cn_msg, * then one or more struct w1_netlink_msg (each with optional data). */ struct w1_netlink_msg { __u8 type; __u8 status; __u16 len; union { __u8 id[8]; struct w1_mst { __u32 id; __u32 res; } mst; } id; __u8 data[0]; }; /** * enum w1_commands - commands available for master or slave operations * * @W1_CMD_READ: read len bytes * @W1_CMD_WRITE: write len bytes * @W1_CMD_SEARCH: initiate a standard search, returns only the slave * devices found during that search * @W1_CMD_ALARM_SEARCH: search for devices that are currently alarming * @W1_CMD_TOUCH: Touches a series of bytes. * @W1_CMD_RESET: sends a bus reset on the given master * @W1_CMD_SLAVE_ADD: adds a slave to the given master, * 8 byte slave id at data[0] * @W1_CMD_SLAVE_REMOVE: removes a slave to the given master, * 8 byte slave id at data[0] * @W1_CMD_LIST_SLAVES: list of slaves registered on this master * @W1_CMD_MAX: number of available commands */ enum w1_commands { W1_CMD_READ = 0, W1_CMD_WRITE, W1_CMD_SEARCH, W1_CMD_ALARM_SEARCH, W1_CMD_TOUCH, W1_CMD_RESET, W1_CMD_SLAVE_ADD, W1_CMD_SLAVE_REMOVE, W1_CMD_LIST_SLAVES, W1_CMD_MAX }; /** * struct w1_netlink_cmd - holds the command and data * * @cmd: one of enum w1_commands * @res: reserved * @len: length of data following w1_netlink_cmd * @data: start address of any following data * * One or more struct w1_netlink_cmd is placed starting at w1_netlink_msg.data * each with optional data. */ struct w1_netlink_cmd { __u8 cmd; __u8 res; __u16 len; __u8 data[0]; }; #ifdef __KERNEL__ void w1_netlink_send(struct w1_master *, struct w1_netlink_msg *); int w1_init_netlink(void); void w1_fini_netlink(void); #endif /* __KERNEL__ */ #endif /* __W1_NETLINK_H */ '>
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 /net/qrtr
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 'net/qrtr')