/* * linux/fs/hfs/bfind.c * * Copyright (C) 2001 * Brad Boyer (flar@allandria.com) * (C) 2003 Ardis Technologies * * Search routines for btrees */ #include #include "btree.h" int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) { void *ptr; fd->tree = tree; fd->bnode = NULL; ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); if (!ptr) return -ENOMEM; fd->search_key = ptr; fd->key = ptr + tree->max_key_len + 2; hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n", tree->cnid, __builtin_return_address(0)); mutex_lock(&tree->tree_lock); return 0; } void hfs_find_exit(struct hfs_find_data *fd) { hfs_bnode_put(fd->bnode); kfree(fd->search_key); hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n", fd->tree->cnid, __builtin_return_address(0)); mutex_unlock(&fd->tree->tree_lock); fd->tree = NULL; } /* Find the record in bnode that best matches key (not greater than...)*/ int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd) { int cmpval; u16 off, len, keylen; int rec; int b, e; int res; b = 0; e = bnode->num_recs - 1; res = -ENOENT; do { rec = (e + b) / 2; len = hfs_brec_lenoff(bnode, rec, &off); keylen = hfs_brec_keylen(bnode, rec); if (keylen == 0) { res = -EINVAL; goto fail; } hfs_bnode_read(bnode, fd->key, off, keylen); cmpval = bnode->tree->keycmp(fd->key, fd->search_key); if (!cmpval) { e = rec; res = 0; goto done; } if (cmpval < 0) b = rec + 1; else e = rec - 1; } while (b <= e); if (rec != e && e >= 0) { len = hfs_brec_lenoff(bnode, e, &off); keylen = hfs_brec_keylen(bnode, e); if (keylen == 0) { res = -EINVAL; goto fail; } hfs_bnode_read(bnode, fd->key, off, keylen); } done: fd->record = e; fd->keyoffset = off; fd->keylength = keylen; fd->entryoffset = off + keylen; fd->entrylength = len - keylen; fail: return res; } /* Traverse a B*Tree from the root to a leaf finding best fit to key */ /* Return allocated copy of node found, set recnum to best record */ int hfs_brec_find(struct hfs_find_data *fd) { struct hfs_btree *tree; struct hfs_bnode *bnode; u32 nidx, parent; __be32 data; int height, res; tree = fd->tree; if (fd->bnode) hfs_bnode_put(fd->bnode); fd->bnode = NULL; nidx = tree->root; if (!nidx) return -ENOENT; height = tree->depth; res = 0; parent = 0; for (;;) { bnode = hfs_bnode_find(tree, nidx); if (IS_ERR(bnode)) { res = PTR_ERR(bnode); bnode = NULL; break; } if (bnode->height != height) goto invalid; if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF)) goto invalid; bnode->parent = parent; res = __hfs_brec_find(bnode, fd); if (!height) break; if (fd->record < 0) goto release; parent = nidx; hfs_bnode_read(bnode, &data, fd->entryoffset, 4); nidx = be32_to_cpu(data); hfs_bnode_put(bnode); } fd->bnode = bnode; return res; invalid: pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n", height, bnode->height, bnode->type, nidx, parent); res = -EIO; release: hfs_bnode_put(bnode); return res; } int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len) { int res; res = hfs_brec_find(fd); if (res) return res; if (fd->entrylength > rec_len) return -EINVAL; hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength); return 0; } int hfs_brec_goto(struct hfs_find_data *fd, int cnt) { struct hfs_btree *tree; struct hfs_bnode *bnode; int idx, res = 0; u16 off, len, keylen; bnode = fd->bnode; tree = bnode->tree; if (cnt < 0) { cnt = -cnt; while (cnt > fd->record) { cnt -= fd->record + 1; fd->record = bnode->num_recs - 1; idx = bnode->prev; if (!idx) { res = -ENOENT; goto out; } hfs_bnode_put(bnode); bnode = hfs_bnode_find(tree, idx); if (IS_ERR(bnode)) { res = PTR_ERR(bnode); bnode = NULL; goto out; } } fd->record -= cnt; } else { while (cnt >= bnode->num_recs - fd->record) { cnt -= bnode->num_recs - fd->record; fd->record = 0; idx = bnode->next; if (!idx) { res = -ENOENT; goto out; } hfs_bnode_put(bnode); bnode = hfs_bnode_find(tree, idx); if (IS_ERR(bnode)) { res = PTR_ERR(bnode); bnode = NULL; goto out; } } fd->record += cnt; } len = hfs_brec_lenoff(bnode, fd->record, &off); keylen = hfs_brec_keylen(bnode, fd->record); if (keylen == 0) { res = -EINVAL; goto out; } fd->keyoffset = off; fd->keylength = keylen; fd->entryoffset = off + keylen; fd->entrylength = len - keylen; hfs_bnode_read(bnode, fd->key, off, keylen); out: fd->bnode = bnode; return res; } ;'>
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 /sound/hda/hdac_i915.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 'sound/hda/hdac_i915.c')