#include <lzma.h>
#include <stdio.h>
#include <linux/compiler.h>
#include "util.h"
#include "debug.h"

#define BUFSIZE 8192

static const char *lzma_strerror(lzma_ret ret)
{
	switch ((int) ret) {
	case LZMA_MEM_ERROR:
		return "Memory allocation failed";
	case LZMA_OPTIONS_ERROR:
		return "Unsupported decompressor flags";
	case LZMA_FORMAT_ERROR:
		return "The input is not in the .xz format";
	case LZMA_DATA_ERROR:
		return "Compressed file is corrupt";
	case LZMA_BUF_ERROR:
		return "Compressed file is truncated or otherwise corrupt";
	default:
		return "Unknown error, possibly a bug";
	}
}

int lzma_decompress_to_file(const char *input, int output_fd)
{
	lzma_action action = LZMA_RUN;
	lzma_stream strm   = LZMA_STREAM_INIT;
	lzma_ret ret;
	int err = -1;

	u8 buf_in[BUFSIZE];
	u8 buf_out[BUFSIZE];
	FILE *infile;

	infile = fopen(input, "rb");
	if (!infile) {
		pr_err("lzma: fopen failed on %s: '%s'\n",
		       input, strerror(errno));
		return -1;
	}

	ret = lzma_stream_decoder(&strm, UINT64_MAX, LZMA_CONCATENATED);
	if (ret != LZMA_OK) {
		pr_err("lzma: lzma_stream_decoder failed %s (%d)\n",
			lzma_strerror(ret), ret);
		goto err_fclose;
	}

	strm.next_in   = NULL;
	strm.avail_in  = 0;
	strm.next_out  = buf_out;
	strm.avail_out = sizeof(buf_out);

	while (1) {
		if (strm.avail_in == 0 && !feof(infile)) {
			strm.next_in  = buf_in;
			strm.avail_in = fread(buf_in, 1, sizeof(buf_in), infile);

			if (ferror(infile)) {
				pr_err("lzma: read error: %s\n", strerror(errno));
				goto err_fclose;
			}

			if (feof(infile))
				action = LZMA_FINISH;
		}

		ret = lzma_code(&strm, action);

		if (strm.avail_out == 0 || ret == LZMA_STREAM_END) {
			ssize_t write_size = sizeof(buf_out) - strm.avail_out;

			if (writen(output_fd, buf_out, write_size) != write_size) {
				pr_err("lzma: write error: %s\n", strerror(errno));
				goto err_fclose;
			}

			strm.next_out  = buf_out;
			strm.avail_out = sizeof(buf_out);
		}

		if (ret != LZMA_OK) {
			if (ret == LZMA_STREAM_END)
				break;

			pr_err("lzma: failed %s\n", lzma_strerror(ret));
			goto err_fclose;
		}
	}

	err = 0;
err_fclose:
	fclose(infile);
	return err;
}
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<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/tools?id=966d2b04e070bc040319aaebfec09e0144dc3341'>tools</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf?id=966d2b04e070bc040319aaebfec09e0144dc3341'>perf</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/perf-sys.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>perf-sys.h</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/tools/perf/perf-sys.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/perf/perf-sys.h?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/tools/perf/perf-sys.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>tools/perf/perf-sys.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/perf-sys.h?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/perf/perf-sys.h?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 'tools/perf/perf-sys.h')</div><table summary='diffstat' class='diffstat'>