/* Helper functions for Dell Mic Mute LED control;
 * to be included from codec driver
 */

#if IS_ENABLED(CONFIG_LEDS_DELL_NETBOOKS)
#include <linux/dell-led.h>

static int dell_led_value;
static int (*dell_led_set_func)(int, int);
static void (*dell_old_cap_hook)(struct hda_codec *,
			         struct snd_kcontrol *,
				 struct snd_ctl_elem_value *);

static void update_dell_wmi_micmute_led(struct hda_codec *codec,
				        struct snd_kcontrol *kcontrol,
					struct snd_ctl_elem_value *ucontrol)
{
	if (dell_old_cap_hook)
		dell_old_cap_hook(codec, kcontrol, ucontrol);

	if (!ucontrol || !dell_led_set_func)
		return;
	if (strcmp("Capture Switch", ucontrol->id.name) == 0 && ucontrol->id.index == 0) {
		/* TODO: How do I verify if it's a mono or stereo here? */
		int val = (ucontrol->value.integer.value[0] || ucontrol->value.integer.value[1]) ? 0 : 1;
		if (val == dell_led_value)
			return;
		dell_led_value = val;
		if (dell_led_set_func)
			dell_led_set_func(DELL_LED_MICMUTE, dell_led_value);
	}
}


static void alc_fixup_dell_wmi(struct hda_codec *codec,
			       const struct hda_fixup *fix, int action)
{
	struct alc_spec *spec = codec->spec;
	bool removefunc = false;

	if (action == HDA_FIXUP_ACT_PROBE) {
		if (!dell_led_set_func)
			dell_led_set_func = symbol_request(dell_app_wmi_led_set);
		if (!dell_led_set_func) {
			codec_warn(codec, "Failed to find dell wmi symbol dell_app_wmi_led_set\n");
			return;
		}

		removefunc = true;
		if (dell_led_set_func(DELL_LED_MICMUTE, false) >= 0) {
			dell_led_value = 0;
			if (spec->gen.num_adc_nids > 1 && !spec->gen.dyn_adc_switch)
				codec_dbg(codec, "Skipping micmute LED control due to several ADCs");
			else {
				dell_old_cap_hook = spec->gen.cap_sync_hook;
				spec->gen.cap_sync_hook = update_dell_wmi_micmute_led;
				removefunc = false;
			}
		}

	}

	if (dell_led_set_func && (action == HDA_FIXUP_ACT_FREE || removefunc)) {
		symbol_put(dell_app_wmi_led_set);
		dell_led_set_func = NULL;
		dell_old_cap_hook = NULL;
	}
}

#else /* CONFIG_LEDS_DELL_NETBOOKS */
static void alc_fixup_dell_wmi(struct hda_codec *codec,
			       const struct hda_fixup *fix, int action)
{
}

#endif /* CONFIG_LEDS_DELL_NETBOOKS */
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<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/net/tc_act/tc_gact.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/net/tc_act/tc_gact.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/include/net/tc_act/tc_gact.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>include/net/tc_act/tc_gact.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/tc_act/tc_gact.h?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/net/tc_act/tc_gact.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 'include/net/tc_act/tc_gact.h')</div><table summary='diffstat' class='diffstat'>