#!/usr/bin/perl -w
# (c) 2009, Tom Zanussi <tzanussi@gmail.com>
# Licensed under the terms of the GNU GPL License version 2

# Display r/w activity for files read/written to for a given program

# The common_* event handler fields are the most useful fields common to
# all events.  They don't necessarily correspond to the 'common_*' fields
# in the status files.  Those fields not available as handler params can
# be retrieved via script functions of the form get_common_*().

use 5.010000;
use strict;
use warnings;

use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/Perf-Trace-Util/lib";
use lib "./Perf-Trace-Util/lib";
use Perf::Trace::Core;
use Perf::Trace::Util;

my $usage = "perf script -s rw-by-file.pl <comm>\n";

my $for_comm = shift or die $usage;

my %reads;
my %writes;

sub syscalls::sys_enter_read
{
    my ($event_name, $context, $common_cpu, $common_secs, $common_nsecs,
	$common_pid, $common_comm, $nr, $fd, $buf, $count) = @_;

    if ($common_comm eq $for_comm) {
	$reads{$fd}{bytes_requested} += $count;
	$reads{$fd}{total_reads}++;
    }
}

sub syscalls::sys_enter_write
{
    my ($event_name, $context, $common_cpu, $common_secs, $common_nsecs,
	$common_pid, $common_comm, $nr, $fd, $buf, $count) = @_;

    if ($common_comm eq $for_comm) {
	$writes{$fd}{bytes_written} += $count;
	$writes{$fd}{total_writes}++;
    }
}

sub trace_end
{
    printf("file read counts for $for_comm:\n\n");

    printf("%6s  %10s  %10s\n", "fd", "# reads", "bytes_requested");
    printf("%6s  %10s  %10s\n", "------", "----------", "-----------");

    foreach my $fd (sort {$reads{$b}{bytes_requested} <=>
			      $reads{$a}{bytes_requested}} keys %reads) {
	my $total_reads = $reads{$fd}{total_reads};
	my $bytes_requested = $reads{$fd}{bytes_requested};
	printf("%6u  %10u  %10u\n", $fd, $total_reads, $bytes_requested);
    }

    printf("\nfile write counts for $for_comm:\n\n");

    printf("%6s  %10s  %10s\n", "fd", "# writes", "bytes_written");
    printf("%6s  %10s  %10s\n", "------", "----------", "-----------");

    foreach my $fd (sort {$writes{$b}{bytes_written} <=>
			      $writes{$a}{bytes_written}} keys %writes) {
	my $total_writes = $writes{$fd}{total_writes};
	my $bytes_written = $writes{$fd}{bytes_written};
	printf("%6u  %10u  %10u\n", $fd, $total_writes, $bytes_written);
    }

    print_unhandled();
}

my %unhandled;

sub print_unhandled
{
    if ((scalar keys %unhandled) == 0) {
	return;
    }

    print "\nunhandled events:\n\n";

    printf("%-40s  %10s\n", "event", "count");
    printf("%-40s  %10s\n", "----------------------------------------",
	   "-----------");

    foreach my $event_name (keys %unhandled) {
	printf("%-40s  %10d\n", $event_name, $unhandled{$event_name});
    }
}

sub trace_unhandled
{
    my ($event_name, $context, $common_cpu, $common_secs, $common_nsecs,
	$common_pid, $common_comm) = @_;

    $unhandled{$event_name}++;
}


437b530d5bb7cb916142fa'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound?h=nds-private-remove&amp;id=3d88460dbd285e7f32437b530d5bb7cb916142fa'>sound</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/pci?h=nds-private-remove&amp;id=3d88460dbd285e7f32437b530d5bb7cb916142fa'>pci</a>/<a href='/cgit.cgi/linux/net-next.git/log/sound/pci/ali5451?h=nds-private-remove&amp;id=3d88460dbd285e7f32437b530d5bb7cb916142fa'>ali5451</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/pci/ali5451?h=nds-private-remove&amp;id=3d88460dbd285e7f32437b530d5bb7cb916142fa&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
='/cgit.cgi/linux/net-next.git/log/sound/soc/cirrus/ep93xx-pcm.c?h=nds-private-remove&amp;id=63fca65d08632fbec9d9b655f671cf08aa1aeeb8&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
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/drivers/usb/core/Makefile?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers/usb/core/Makefile?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/drivers/usb/core/Makefile?id=966d2b04e070bc040319aaebfec09e0144dc3341'>drivers/usb/core/Makefile</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/core/Makefile?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers/usb/core/Makefile?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 'drivers/usb/core/Makefile')</div><table summary='diffstat' class='diffstat'>