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From: Octavian Purdila <tavi@cs.pub.ro>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: lkml <linux-kernel@vger.kernel.org>,
	linux-usb@vger.kernel.org, tglx@linutronix.de,
	Lee Jones <lee.jones@linaro.org>
Subject: Re: [PATCH REPOST] mfd: dln2: use irqsave() in USB's complete callback
Date: Mon, 2 Jul 2018 00:07:22 +0200	[thread overview]
Message-ID: <CAMoF9u0ZxNqKLV6FEjpHkGGuh8_V7zFQ_VpK-Y-fmbkSwL31Rg@mail.gmail.com> (raw)
In-Reply-To: <20180701154108.13233-1-bigeasy@linutronix.de>

On Sun, Jul 1, 2018 at 5:41 PM, Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
> The USB completion callback does not disable interrupts while acquiring
> the lock. We want to remove the local_irq_disable() invocation from
> __usb_hcd_giveback_urb() and therefore it is required for the callback
> handler to disable the interrupts while acquiring the lock.
> The callback may be invoked either in IRQ or BH context depending on the
> USB host controller.
> Use the _irqsave() variant of the locking primitives.
>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Octavian Purdila <octavian.purdila@intel.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  drivers/mfd/dln2.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> index 704e189ca162..1ef3c92f32e0 100644
> --- a/drivers/mfd/dln2.c
> +++ b/drivers/mfd/dln2.c
> @@ -194,6 +194,7 @@ static bool dln2_transfer_complete(struct dln2_dev *dln2, struct urb *urb,
>         struct device *dev = &dln2->interface->dev;
>         struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
>         struct dln2_rx_context *rxc;
> +       unsigned long flags;
>         bool valid_slot = false;
>
>         if (rx_slot >= DLN2_MAX_RX_SLOTS)
> @@ -206,13 +207,13 @@ static bool dln2_transfer_complete(struct dln2_dev *dln2, struct urb *urb,
>          * context elsewhere in this driver. This function (or its callers) are
>          * also not exported to other modules.
>          */
> -       spin_lock(&rxs->lock);
> +       spin_lock_irqsave(&rxs->lock, flags);


I don't think disabling the IRQ is necessary, please see the comment
above and also this discussion:

https://www.spinics.net/lists/linux-usb/msg115214.html

WARNING: multiple messages have this Message-ID (diff)
From: Octavian Purdila <tavi@cs.pub.ro>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: lkml <linux-kernel@vger.kernel.org>,
	linux-usb@vger.kernel.org, tglx@linutronix.de,
	Lee Jones <lee.jones@linaro.org>
Subject: [REPOST] mfd: dln2: use irqsave() in USB's complete callback
Date: Mon, 2 Jul 2018 00:07:22 +0200	[thread overview]
Message-ID: <CAMoF9u0ZxNqKLV6FEjpHkGGuh8_V7zFQ_VpK-Y-fmbkSwL31Rg@mail.gmail.com> (raw)

On Sun, Jul 1, 2018 at 5:41 PM, Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
> The USB completion callback does not disable interrupts while acquiring
> the lock. We want to remove the local_irq_disable() invocation from
> __usb_hcd_giveback_urb() and therefore it is required for the callback
> handler to disable the interrupts while acquiring the lock.
> The callback may be invoked either in IRQ or BH context depending on the
> USB host controller.
> Use the _irqsave() variant of the locking primitives.
>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Octavian Purdila <octavian.purdila@intel.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  drivers/mfd/dln2.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> index 704e189ca162..1ef3c92f32e0 100644
> --- a/drivers/mfd/dln2.c
> +++ b/drivers/mfd/dln2.c
> @@ -194,6 +194,7 @@ static bool dln2_transfer_complete(struct dln2_dev *dln2, struct urb *urb,
>         struct device *dev = &dln2->interface->dev;
>         struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
>         struct dln2_rx_context *rxc;
> +       unsigned long flags;
>         bool valid_slot = false;
>
>         if (rx_slot >= DLN2_MAX_RX_SLOTS)
> @@ -206,13 +207,13 @@ static bool dln2_transfer_complete(struct dln2_dev *dln2, struct urb *urb,
>          * context elsewhere in this driver. This function (or its callers) are
>          * also not exported to other modules.
>          */
> -       spin_lock(&rxs->lock);
> +       spin_lock_irqsave(&rxs->lock, flags);


I don't think disabling the IRQ is necessary, please see the comment
above and also this discussion:

https://www.spinics.net/lists/linux-usb/msg115214.html
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  reply	other threads:[~2018-07-01 22:07 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-01 15:41 [PATCH REPOST] mfd: dln2: use irqsave() in USB's complete callback Sebastian Andrzej Siewior
2018-07-01 15:41 ` [REPOST] " Sebastian Andrzej Siewior
2018-07-01 22:07 ` Octavian Purdila [this message]
2018-07-01 22:07   ` Octavian Purdila
2018-07-02  6:24   ` [PATCH REPOST] " Johan Hovold
2018-07-02  6:24     ` [REPOST] " Johan Hovold
2018-07-02  7:31     ` [PATCH v2] " Sebastian Andrzej Siewior
2018-07-02  7:31       ` [v2] " Sebastian Andrzej Siewior
2018-07-04  7:40       ` [PATCH v2] " Lee Jones
2018-07-04  7:40         ` [v2] " Lee Jones

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