From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: linux-wireless@vger.kernel.org, Felix Fietkau <nbd@nbd.name>
Subject: Re: [RFC 3/3] mt76x02: remove bogus mutex usage
Date: Tue, 16 Apr 2019 11:29:36 +0200 [thread overview]
Message-ID: <20190416092935.GC11046@localhost.localdomain> (raw)
In-Reply-To: <20190416091305.4218-4-sgruszka@redhat.com>
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> mac .start(), .stop() callbacks are never called concurrently with other
> mac callbacks. The only concurencly is with mt76 works which we cancel
> on stop() and schedule on start().
>
> This fixes possible deadlock on cancel_delayed_work_sync(&dev->mac_work)
> as mac_work also take mutex.
>
> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> ---
> .../net/wireless/mediatek/mt76/mt76x0/pci.c | 6 -----
> .../net/wireless/mediatek/mt76/mt76x0/usb.c | 22 +++++--------------
> .../wireless/mediatek/mt76/mt76x2/pci_main.c | 5 -----
> .../wireless/mediatek/mt76/mt76x2/usb_main.c | 10 ++-------
> 4 files changed, 7 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c b/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c
> index 156d3d064ba0..ac979128386a 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c
> @@ -25,8 +25,6 @@ static int mt76x0e_start(struct ieee80211_hw *hw)
> {
> struct mt76x02_dev *dev = hw->priv;
>
> - mutex_lock(&dev->mt76.mutex);
> -
> mt76x02_mac_start(dev);
> mt76x0_phy_calibrate(dev, true);
> ieee80211_queue_delayed_work(dev->mt76.hw, &dev->mac_work,
> @@ -35,8 +33,6 @@ static int mt76x0e_start(struct ieee80211_hw *hw)
> MT_CALIBRATE_INTERVAL);
> set_bit(MT76_STATE_RUNNING, &dev->mt76.state);
>
> - mutex_unlock(&dev->mt76.mutex);
> -
> return 0;
> }
>
> @@ -62,10 +58,8 @@ static void mt76x0e_stop(struct ieee80211_hw *hw)
> {
> struct mt76x02_dev *dev = hw->priv;
>
> - mutex_lock(&dev->mt76.mutex);
> clear_bit(MT76_STATE_RUNNING, &dev->mt76.state);
> mt76x0e_stop_hw(dev);
> - mutex_unlock(&dev->mt76.mutex);
> }
>
> static void
[..]
> static const struct ieee80211_ops mt76x0u_ops = {
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/pci_main.c b/drivers/net/wireless/mediatek/mt76/mt76x2/pci_main.c
> index 16dc8e2451b5..1b5caabebff5 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76x2/pci_main.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/pci_main.c
> @@ -22,8 +22,6 @@ mt76x2_start(struct ieee80211_hw *hw)
> struct mt76x02_dev *dev = hw->priv;
> int ret;
>
> - mutex_lock(&dev->mt76.mutex);
> -
> ret = mt76x2_mac_start(dev);
> if (ret)
> goto out;
You can remove goto here and just return ret (same below)
> @@ -40,7 +38,6 @@ mt76x2_start(struct ieee80211_hw *hw)
> set_bit(MT76_STATE_RUNNING, &dev->mt76.state);
>
> out:
> - mutex_unlock(&dev->mt76.mutex);
> return ret;
> }
>
> @@ -49,10 +46,8 @@ mt76x2_stop(struct ieee80211_hw *hw)
> {
> struct mt76x02_dev *dev = hw->priv;
>
> - mutex_lock(&dev->mt76.mutex);
> clear_bit(MT76_STATE_RUNNING, &dev->mt76.state);
> mt76x2_stop_hardware(dev);
> - mutex_unlock(&dev->mt76.mutex);
> }
>
> static int
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c b/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c
> index 0771de210c6a..32726b4906ea 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c
> @@ -21,30 +21,24 @@ static int mt76x2u_start(struct ieee80211_hw *hw)
> struct mt76x02_dev *dev = hw->priv;
> int ret;
>
> - mutex_lock(&dev->mt76.mutex);
> -
> ret = mt76x2u_mac_start(dev);
> if (ret)
> - goto out;
> + return ret;
>
> ieee80211_queue_delayed_work(mt76_hw(dev), &dev->mac_work,
> MT_MAC_WORK_INTERVAL);
> set_bit(MT76_STATE_RUNNING, &dev->mt76.state);
>
> -out:
> - mutex_unlock(&dev->mt76.mutex);
> - return ret;
> + return 0;
> }
>
> static void mt76x2u_stop(struct ieee80211_hw *hw)
> {
> struct mt76x02_dev *dev = hw->priv;
>
> - mutex_lock(&dev->mt76.mutex);
> clear_bit(MT76_STATE_RUNNING, &dev->mt76.state);
> mt76u_stop_tx(&dev->mt76);
> mt76x2u_stop_hw(dev);
> - mutex_unlock(&dev->mt76.mutex);
> }
>
> static int
> --
> 2.20.1
>
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prev parent reply other threads:[~2019-04-16 9:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 9:13 [RFC 0/3] mt76: suspend/stop/removal fixes Stanislaw Gruszka
2019-04-16 9:13 ` [RFC 1/3] mt76x02u: remove bogus stop on suspend Stanislaw Gruszka
2019-04-16 9:13 ` [RFC 2/3] mt76usb: fix tx/rx stop Stanislaw Gruszka
2019-04-23 7:59 ` Stanislaw Gruszka
2019-04-16 9:13 ` [RFC 3/3] mt76x02: remove bogus mutex usage Stanislaw Gruszka
2019-04-16 9:29 ` Lorenzo Bianconi [this message]
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