#include #include #include #include #include #include #include #include static const struct genl_multicast_group quota_mcgrps[] = { { .name = "events", }, }; /* Netlink family structure for quota */ static struct genl_family quota_genl_family __ro_after_init = { .module = THIS_MODULE, .hdrsize = 0, .name = "VFS_DQUOT", .version = 1, .maxattr = QUOTA_NL_A_MAX, .mcgrps = quota_mcgrps, .n_mcgrps = ARRAY_SIZE(quota_mcgrps), }; /** * quota_send_warning - Send warning to userspace about exceeded quota * @qid: The kernel internal quota identifier. * @dev: The device on which the fs is mounted (sb->s_dev) * @warntype: The type of the warning: QUOTA_NL_... * * This can be used by filesystems (including those which don't use * dquot) to send a message to userspace relating to quota limits. * */ void quota_send_warning(struct kqid qid, dev_t dev, const char warntype) { static atomic_t seq; struct sk_buff *skb; void *msg_head; int ret; int msg_size = 4 * nla_total_size(sizeof(u32)) + 2 * nla_total_size_64bit(sizeof(u64)); /* We have to allocate using GFP_NOFS as we are called from a * filesystem performing write and thus further recursion into * the fs to free some data could cause deadlocks. */ skb = genlmsg_new(msg_size, GFP_NOFS); if (!skb) { printk(KERN_ERR "VFS: Not enough memory to send quota warning.\n"); return; } msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq), "a_genl_family, 0, QUOTA_NL_C_WARNING); if (!msg_head) { printk(KERN_ERR "VFS: Cannot store netlink header in quota warning.\n"); goto err_out; } ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type); if (ret) goto attr_err_out; ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID, from_kqid_munged(&init_user_ns, qid), QUOTA_NL_A_PAD); if (ret) goto attr_err_out; ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype); if (ret) goto attr_err_out; ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev)); if (ret) goto attr_err_out; ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev)); if (ret) goto attr_err_out; ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID, from_kuid_munged(&init_user_ns, current_uid()), QUOTA_NL_A_PAD); if (ret) goto attr_err_out; genlmsg_end(skb, msg_head); genlmsg_multicast("a_genl_family, skb, 0, 0, GFP_NOFS); return; attr_err_out: printk(KERN_ERR "VFS: Not enough space to compose quota message!\n"); err_out: kfree_skb(skb); } EXPORT_SYMBOL(quota_send_warning); static int __init quota_init(void) { if (genl_register_family("a_genl_family) != 0) printk(KERN_ERR "VFS: Failed to create quota netlink interface.\n"); return 0; }; fs_initcall(quota_init); ubmit' value='search'/>
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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/lguest/.gitignore
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/lguest/.gitignore')