/* * digi00x-proc.c - a part of driver for Digidesign Digi 002/003 family * * Copyright (c) 2014-2015 Takashi Sakamoto * * Licensed under the terms of the GNU General Public License, version 2. */ #include "digi00x.h" static int get_optical_iface_mode(struct snd_dg00x *dg00x, enum snd_dg00x_optical_mode *mode) { __be32 data; int err; err = snd_fw_transaction(dg00x->unit, TCODE_READ_QUADLET_REQUEST, DG00X_ADDR_BASE + DG00X_OFFSET_OPT_IFACE_MODE, &data, sizeof(data), 0); if (err >= 0) *mode = be32_to_cpu(data) & 0x01; return err; } static void proc_read_clock(struct snd_info_entry *entry, struct snd_info_buffer *buf) { static const char *const source_name[] = { [SND_DG00X_CLOCK_INTERNAL] = "internal", [SND_DG00X_CLOCK_SPDIF] = "s/pdif", [SND_DG00X_CLOCK_ADAT] = "adat", [SND_DG00X_CLOCK_WORD] = "word clock", }; static const char *const optical_name[] = { [SND_DG00X_OPT_IFACE_MODE_ADAT] = "adat", [SND_DG00X_OPT_IFACE_MODE_SPDIF] = "s/pdif", }; struct snd_dg00x *dg00x = entry->private_data; enum snd_dg00x_optical_mode mode; unsigned int rate; enum snd_dg00x_clock clock; bool detect; if (get_optical_iface_mode(dg00x, &mode) < 0) return; if (snd_dg00x_stream_get_local_rate(dg00x, &rate) < 0) return; if (snd_dg00x_stream_get_clock(dg00x, &clock) < 0) return; snd_iprintf(buf, "Optical mode: %s\n", optical_name[mode]); snd_iprintf(buf, "Sampling Rate: %d\n", rate); snd_iprintf(buf, "Clock Source: %s\n", source_name[clock]); if (clock == SND_DG00X_CLOCK_INTERNAL) return; if (snd_dg00x_stream_check_external_clock(dg00x, &detect) < 0) return; snd_iprintf(buf, "External source: %s\n", detect ? "detected" : "not"); if (!detect) return; if (snd_dg00x_stream_get_external_rate(dg00x, &rate) >= 0) snd_iprintf(buf, "External sampling rate: %d\n", rate); } void snd_dg00x_proc_init(struct snd_dg00x *dg00x) { struct snd_info_entry *root, *entry; /* * All nodes are automatically removed at snd_card_disconnect(), * by following to link list. */ root = snd_info_create_card_entry(dg00x->card, "firewire", dg00x->card->proc_root); if (root == NULL) return; root->mode = S_IFDIR | S_IRUGO | S_IXUGO; if (snd_info_register(root) < 0) { snd_info_free_entry(root); return; } entry = snd_info_create_card_entry(dg00x->card, "clock", root); if (entry == NULL) { snd_info_free_entry(root); return; } snd_info_set_text_ops(entry, dg00x, proc_read_clock); if (snd_info_register(entry) < 0) { snd_info_free_entry(entry); snd_info_free_entry(root); } } e=''/>
path: root/drivers/usb/host/ehci-q.c
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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 /drivers/usb/host/ehci-q.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 'drivers/usb/host/ehci-q.c')