#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "tests.h"
#include "util.h"
#include "session.h"
#include "evlist.h"
#include "debug.h"

#define TEMPL "/tmp/perf-test-XXXXXX"
#define DATA_SIZE	10

static int get_temp(char *path)
{
	int fd;

	strcpy(path, TEMPL);

	fd = mkstemp(path);
	if (fd < 0) {
		perror("mkstemp failed");
		return -1;
	}

	close(fd);
	return 0;
}

static int session_write_header(char *path)
{
	struct perf_session *session;
	struct perf_data_file file = {
		.path = path,
		.mode = PERF_DATA_MODE_WRITE,
	};

	session = perf_session__new(&file, false, NULL);
	TEST_ASSERT_VAL("can't get session", session);

	session->evlist = perf_evlist__new_default();
	TEST_ASSERT_VAL("can't get evlist", session->evlist);

	perf_header__set_feat(&session->header, HEADER_CPU_TOPOLOGY);
	perf_header__set_feat(&session->header, HEADER_NRCPUS);

	session->header.data_size += DATA_SIZE;

	TEST_ASSERT_VAL("failed to write header",
			!perf_session__write_header(session, session->evlist, file.fd, true));

	perf_session__delete(session);

	return 0;
}

static int check_cpu_topology(char *path, struct cpu_map *map)
{
	struct perf_session *session;
	struct perf_data_file file = {
		.path = path,
		.mode = PERF_DATA_MODE_READ,
	};
	int i;

	session = perf_session__new(&file, false, NULL);
	TEST_ASSERT_VAL("can't get session", session);

	for (i = 0; i < session->header.env.nr_cpus_online; i++) {
		pr_debug("CPU %d, core %d, socket %d\n", i,
			 session->header.env.cpu[i].core_id,
			 session->header.env.cpu[i].socket_id);
	}

	for (i = 0; i < map->nr; i++) {
		TEST_ASSERT_VAL("Core ID doesn't match",
			(session->header.env.cpu[map->map[i]].core_id == (cpu_map__get_core(map, i, NULL) & 0xffff)));

		TEST_ASSERT_VAL("Socket ID doesn't match",
			(session->header.env.cpu[map->map[i]].socket_id == cpu_map__get_socket(map, i, NULL)));
	}

	perf_session__delete(session);

	return 0;
}

int test_session_topology(int subtest __maybe_unused)
{
	char path[PATH_MAX];
	struct cpu_map *map;
	int ret = -1;

	TEST_ASSERT_VAL("can't get templ file", !get_temp(path));

	pr_debug("templ file: %s\n", path);

	if (session_write_header(path))
		goto free_path;

	map = cpu_map__new(NULL);
	if (map == NULL) {
		pr_debug("failed to get system cpumap\n");
		goto free_path;
	}

	if (check_cpu_topology(path, map))
		goto free_map;
	ret = 0;

free_map:
	cpu_map__put(map);
free_path:
	unlink(path);
	return ret;
}
'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include?id=966d2b04e070bc040319aaebfec09e0144dc3341'>include</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include/pcmcia?id=966d2b04e070bc040319aaebfec09e0144dc3341'>pcmcia</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='966d2b04e070bc040319aaebfec09e0144dc3341'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</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/include/pcmcia?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/pcmcia?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/include/pcmcia?id=966d2b04e070bc040319aaebfec09e0144dc3341'>include/pcmcia</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/pcmcia?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/pcmcia?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 'include/pcmcia')</div><table summary='diffstat' class='diffstat'>