#ifndef __TRACE_AGENT_H__
#define __TRACE_AGENT_H__
#include <pthread.h>
#include <stdbool.h>

#define MAX_CPUS	256
#define PIPE_INIT       (1024*1024)

/*
 * agent_info - structure managing total information of guest agent
 * @pipe_size:	size of pipe (default 1MB)
 * @use_stdout:	set to true when o option is added (default false)
 * @cpus:	total number of CPUs
 * @ctl_fd:	fd of control path, /dev/virtio-ports/agent-ctl-path
 * @rw_ti:	structure managing information of read/write threads
 */
struct agent_info {
	unsigned long pipe_size;
	bool use_stdout;
	int cpus;
	int ctl_fd;
	struct rw_thread_info *rw_ti[MAX_CPUS];
};

/*
 * rw_thread_info - structure managing a read/write thread a cpu
 * @cpu_num:	cpu number operating this read/write thread
 * @in_fd:	fd of reading trace data path in cpu_num
 * @out_fd:	fd of writing trace data path in cpu_num
 * @read_pipe:	fd of read pipe
 * @write_pipe:	fd of write pipe
 * @pipe_size:	size of pipe (default 1MB)
 */
struct rw_thread_info {
	int cpu_num;
	int in_fd;
	int out_fd;
	int read_pipe;
	int write_pipe;
	unsigned long pipe_size;
};

/* use for stopping rw threads */
extern bool global_sig_receive;

/* use for notification */
extern bool global_run_operation;
extern pthread_mutex_t mutex_notify;
extern pthread_cond_t cond_wakeup;

/* for controller of read/write threads */
extern int rw_ctl_init(const char *ctl_path);
extern void *rw_ctl_loop(int ctl_fd);

/* for trace read/write thread */
extern void *rw_thread_info_new(void);
extern void *rw_thread_init(int cpu, const char *in_path, const char *out_path,
			bool stdout_flag, unsigned long pipe_size,
			struct rw_thread_info *rw_ti);
extern pthread_t rw_thread_run(struct rw_thread_info *rw_ti);

static inline void *zalloc(size_t size)
{
	return calloc(1, size);
}

#define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
#define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__)
#ifdef DEBUG
#define pr_debug(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
#else
#define pr_debug(format, ...) do {} while (0)
#endif

#endif /*__TRACE_AGENT_H__*/
linux/net-next.git/diff/sound/usb/caiaq/audio.c?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26'>diff</a></td><td class='form'><form class='right' method='get' action='/cgit.cgi/linux/net-next.git/log/sound/usb/caiaq/audio.c'>
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26'>sound</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/usb?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26'>usb</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/usb/caiaq?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26'>caiaq</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/usb/caiaq/audio.c?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26'>audio.c</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/sound/usb/caiaq/audio.c?h=nds-private-remove&amp;id=c56108b58ab870892277940a1def0d6b153f3e26&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
0</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/xfs/xfs_rmap_item.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/fs/xfs/xfs_rmap_item.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/fs/xfs/xfs_rmap_item.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>fs/xfs/xfs_rmap_item.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/xfs/xfs_rmap_item.c?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/fs/xfs/xfs_rmap_item.c?id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>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 &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'fs/xfs/xfs_rmap_item.c')</div><table summary='diffstat' class='diffstat'>