/* * Copyright (c) by Jaroslav Kysela * GUS's memory access via proc filesystem * * * 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 * */ #include #include #include #include struct gus_proc_private { int rom; /* data are in ROM */ unsigned int address; unsigned int size; struct snd_gus_card * gus; }; static ssize_t snd_gf1_mem_proc_dump(struct snd_info_entry *entry, void *file_private_data, struct file *file, char __user *buf, size_t count, loff_t pos) { struct gus_proc_private *priv = entry->private_data; struct snd_gus_card *gus = priv->gus; int err; err = snd_gus_dram_read(gus, buf, pos, count, priv->rom); if (err < 0) return err; return count; } static void snd_gf1_mem_proc_free(struct snd_info_entry *entry) { struct gus_proc_private *priv = entry->private_data; kfree(priv); } static struct snd_info_entry_ops snd_gf1_mem_proc_ops = { .read = snd_gf1_mem_proc_dump, }; int snd_gf1_mem_proc_init(struct snd_gus_card * gus) { int idx; char name[16]; struct gus_proc_private *priv; struct snd_info_entry *entry; for (idx = 0; idx < 4; idx++) { if (gus->gf1.mem_alloc.banks_8[idx].size > 0) { priv = kzalloc(sizeof(*priv), GFP_KERNEL); if (priv == NULL) return -ENOMEM; priv->gus = gus; sprintf(name, "gus-ram-%i", idx); if (! snd_card_proc_new(gus->card, name, &entry)) { entry->content = SNDRV_INFO_CONTENT_DATA; entry->private_data = priv; entry->private_free = snd_gf1_mem_proc_free; entry->c.ops = &snd_gf1_mem_proc_ops; priv->address = gus->gf1.mem_alloc.banks_8[idx].address; priv->size = entry->size = gus->gf1.mem_alloc.banks_8[idx].size; } } } for (idx = 0; idx < 4; idx++) { if (gus->gf1.rom_present & (1 << idx)) { priv = kzalloc(sizeof(*priv), GFP_KERNEL); if (priv == NULL) return -ENOMEM; priv->rom = 1; priv->gus = gus; sprintf(name, "gus-rom-%i", idx); if (! snd_card_proc_new(gus->card, name, &entry)) { entry->content = SNDRV_INFO_CONTENT_DATA; entry->private_data = priv; entry->private_free = snd_gf1_mem_proc_free; entry->c.ops = &snd_gf1_mem_proc_ops; priv->address = idx * 4096 * 1024; priv->size = entry->size = gus->gf1.rom_memory; } } } return 0; } '>usb/renesas_usbhs
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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/renesas_usbhs
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/renesas_usbhs')