/* Copyright (c) 2016 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <linux/bpf.h>
#include <string.h>
#include <linux/perf_event.h>
#include <errno.h>
#include <assert.h>
#include <stdbool.h>
#include <sys/resource.h>
#include "libbpf.h"
#include "bpf_load.h"

#define PRINT_RAW_ADDR 0

static void print_ksym(__u64 addr)
{
	struct ksym *sym;

	if (!addr)
		return;
	sym = ksym_search(addr);
	if (PRINT_RAW_ADDR)
		printf("%s/%llx;", sym->name, addr);
	else
		printf("%s;", sym->name);
}

#define TASK_COMM_LEN 16

struct key_t {
	char waker[TASK_COMM_LEN];
	char target[TASK_COMM_LEN];
	__u32 wret;
	__u32 tret;
};

static void print_stack(struct key_t *key, __u64 count)
{
	__u64 ip[PERF_MAX_STACK_DEPTH] = {};
	static bool warned;
	int i;

	printf("%s;", key->target);
	if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
		printf("---;");
	} else {
		for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
			print_ksym(ip[i]);
	}
	printf("-;");
	if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
		printf("---;");
	} else {
		for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
			print_ksym(ip[i]);
	}
	printf(";%s %lld\n", key->waker, count);

	if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
		printf("stackmap collisions seen. Consider increasing size\n");
		warned = true;
	} else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
		printf("err stackid %d %d\n", key->tret, key->wret);
	}
}

static void print_stacks(int fd)
{
	struct key_t key = {}, next_key;
	__u64 value;

	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
		bpf_map_lookup_elem(fd, &next_key, &value);
		print_stack(&next_key, value);
		key = next_key;
	}
}

static void int_exit(int sig)
{
	print_stacks(map_fd[0]);
	exit(0);
}

int main(int argc, char **argv)
{
	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
	char filename[256];
	int delay = 1;

	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
	setrlimit(RLIMIT_MEMLOCK, &r);

	signal(SIGINT, int_exit);

	if (load_kallsyms()) {
		printf("failed to process /proc/kallsyms\n");
		return 2;
	}

	if (load_bpf_file(filename)) {
		printf("%s", bpf_log_buf);
		return 1;
	}

	if (argc > 1)
		delay = atoi(argv[1]);
	sleep(delay);
	print_stacks(map_fd[0]);

	return 0;
}
eb1fda2d530d3b268eef542c5414e54bf1a'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>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/?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>include</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include/drm?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>drm</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include/drm/drm_plane.h?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>drm_plane.h</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='91539eb1fda2d530d3b268eef542c5414e54bf1a'/><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>Iago Abal &lt;mail@iagoabal.eu&gt;</td><td class='right'>2017-01-11 14:00:21 +0100</td></tr>
<tr><th>committer</th><td>Vinod Koul &lt;vinod.koul@intel.com&gt;</td><td class='right'>2017-01-25 15:35:11 +0530</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/drm/drm_plane.h?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>91539eb1fda2d530d3b268eef542c5414e54bf1a</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/drm/drm_plane.h?id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>960f5ca6342ad20837aff18aad6e8ecd7da32fd6</a> /<a href='/cgit.cgi/linux/net-next.git/tree/include/drm/drm_plane.h?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>include/drm/drm_plane.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/drm/drm_plane.h?h=nds-private-remove&amp;id=6610d0edf6dc7ee97e46ab3a538a565c79d26199'>6610d0edf6dc7ee97e46ab3a538a565c79d26199</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/drm/drm_plane.h?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a&amp;id2=6610d0edf6dc7ee97e46ab3a538a565c79d26199'>diff</a>)</td></tr></table>
<div class='commit-subject'>dmaengine: pl330: fix double lock</div><div class='commit-msg'>The static bug finder EBA (http://www.iagoabal.eu/eba/) reported the
following double-lock bug:

    Double lock:
    1. spin_lock_irqsave(pch-&gt;lock, flags) at pl330_free_chan_resources:2236;
    2. call to function `pl330_release_channel' immediately after;
    3. call to function `dma_pl330_rqcb' in line 1753;
    4. spin_lock_irqsave(pch-&gt;lock, flags) at dma_pl330_rqcb:1505.

I have fixed it as suggested by Marek Szyprowski.

First, I have replaced `pch-&gt;lock' with `pl330-&gt;lock' in functions
`pl330_alloc_chan_resources' and `pl330_free_chan_resources'. This avoids
the double-lock by acquiring a different lock than `dma_pl330_rqcb'.

NOTE that, as a result, `pl330_free_chan_resources' executes
`list_splice_tail_init' on `pch-&gt;work_list' under lock `pl330-&gt;lock',
whereas in the rest of the code `pch-&gt;work_list' is protected by
`pch-&gt;lock'. I don't know if this may cause race conditions. Similarly
`pch-&gt;cyclic' is written by `pl330_alloc_chan_resources' under
`pl330-&gt;lock' but read by `pl330_tx_submit' under `pch-&gt;lock'.

Second, I have removed locking from `pl330_request_channel' and
`pl330_release_channel' functions. Function `pl330_request_channel' is
only called from `pl330_alloc_chan_resources', so the lock is already
held. Function `pl330_release_channel' is called from
`pl330_free_chan_resources', which already holds the lock, and from
`pl330_del'. Function `pl330_del' is called in an error path of
`pl330_probe' and at the end of `pl330_remove', but I assume that there
cannot be concurrent accesses to the protected data at those points.

Signed-off-by: Iago Abal &lt;mail@iagoabal.eu&gt;
Reviewed-by: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Signed-off-by: Vinod Koul &lt;vinod.koul@intel.com&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=91539eb1fda2d530d3b268eef542c5414e54bf1a'>Diffstat</a> (limited to 'include/drm/drm_plane.h')</div><table summary='diffstat' class='diffstat'>