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Message-ID: <87y0rwtcyf.fsf@intel.com>
Date: Wed, 06 Aug 2025 13:25:12 -0700
From: Vinicius Costa Gomes <vinicius.gomes@...el.com>
To: Dave Jiang <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>,
Fenghua Yu <fenghua.yu@...el.com>, Dan Williams <dan.j.williams@...el.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/9] dmaengine: idxd: Fix lockdep warnings when calling
idxd_device_config()
Dave Jiang <dave.jiang@...el.com> writes:
> On 8/4/25 6:27 PM, Vinicius Costa Gomes wrote:
>> idxd_device_config() should only be called with idxd->dev_lock held.
>> Hold the lock to the calls that were missing.
>>
>> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
>
> Patch looks fine. What about doing something like this:
>
> ---
>
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 5cf419fe6b46..06c182ec3c04 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -1103,11 +1103,15 @@ static int idxd_wqs_setup(struct idxd_device *idxd)
> return 0;
> }
>
> -int idxd_device_config(struct idxd_device *idxd)
> +int idxd_device_config_locked(struct idxd_device *idxd)
> {
> int rc;
>
> lockdep_assert_held(&idxd->dev_lock);
> +
> + if (!test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
> + return -EPERM;
> +
> rc = idxd_wqs_setup(idxd);
> if (rc < 0)
> return rc;
> @@ -1129,6 +1133,12 @@ int idxd_device_config(struct idxd_device *idxd)
> return 0;
> }
>
> +int idxd_device_config(struct idxd_device *idxd)
> +{
> + guard(spinlock)(&idxd->dev_lock);
> + return idxd_device_config_locked(idxd);
> +}
> +
This gave me the idea that moving the lock to idxd_device_config() might
be a better idea. As the _locked() variant doesn't seem to be used, I
don't see why we should keep it around. Will give it a try and see how
it looks.
Thanks.
> static int idxd_wq_load_config(struct idxd_wq *wq)
> {
> struct idxd_device *idxd = wq->idxd;
> @@ -1434,11 +1444,7 @@ int idxd_drv_enable_wq(struct idxd_wq *wq)
> }
> }
>
> - rc = 0;
> - spin_lock(&idxd->dev_lock);
> - if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
> - rc = idxd_device_config(idxd);
> - spin_unlock(&idxd->dev_lock);
> + rc = idxd_device_config(idxd);
> if (rc < 0) {
> dev_dbg(dev, "Writing wq %d config failed: %d\n", wq->id, rc);
> goto err;
> @@ -1521,7 +1527,7 @@ EXPORT_SYMBOL_NS_GPL(idxd_drv_disable_wq, "IDXD");
> int idxd_device_drv_probe(struct idxd_dev *idxd_dev)
> {
> struct idxd_device *idxd = idxd_dev_to_idxd(idxd_dev);
> - int rc = 0;
> + int rc;
>
> /*
> * Device should be in disabled state for the idxd_drv to load. If it's in
> @@ -1534,10 +1540,7 @@ int idxd_device_drv_probe(struct idxd_dev *idxd_dev)
> }
>
> /* Device configuration */
> - spin_lock(&idxd->dev_lock);
> - if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
> - rc = idxd_device_config(idxd);
> - spin_unlock(&idxd->dev_lock);
> + rc = idxd_device_config(idxd);
> if (rc < 0)
> return -ENXIO;
>
> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
> index 74e6695881e6..f15bc2281c6b 100644
> --- a/drivers/dma/idxd/idxd.h
> +++ b/drivers/dma/idxd/idxd.h
> @@ -760,6 +760,7 @@ int idxd_device_disable(struct idxd_device *idxd);
> void idxd_device_reset(struct idxd_device *idxd);
> void idxd_device_clear_state(struct idxd_device *idxd);
> int idxd_device_config(struct idxd_device *idxd);
> +int idxd_device_config_locked(struct idxd_device *idxd);
> void idxd_device_drain_pasid(struct idxd_device *idxd, int pasid);
> int idxd_device_load_config(struct idxd_device *idxd);
> int idxd_device_request_int_handle(struct idxd_device *idxd, int idx, int *handle,
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 80355d03004d..193b9282e30f 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -1091,12 +1091,10 @@ static void idxd_reset_done(struct pci_dev *pdev)
> idxd_device_config_restore(idxd, idxd->idxd_saved);
>
> /* Re-configure IDXD device if allowed. */
> - if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags)) {
> - rc = idxd_device_config(idxd);
> - if (rc < 0) {
> - dev_err(dev, "HALT: %s config fails\n", idxd_name);
> - goto out;
> - }
> + rc = idxd_device_config(idxd);
> + if (rc < 0) {
> + dev_err(dev, "HALT: %s config fails\n", idxd_name);
> + goto out;
> }
>
> /* Bind IDXD device to driver. */
>
>
>> ---
>> drivers/dma/idxd/init.c | 2 ++
>> drivers/dma/idxd/irq.c | 2 ++
>> 2 files changed, 4 insertions(+)
>>
>> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
>> index 35bdefd3728bb851beb0f235fae7c6d71bd59239..d828d352ab008127e5e442e7072c9d5df0f2c6cf 100644
>> --- a/drivers/dma/idxd/init.c
>> +++ b/drivers/dma/idxd/init.c
>> @@ -1091,7 +1091,9 @@ static void idxd_reset_done(struct pci_dev *pdev)
>>
>> /* Re-configure IDXD device if allowed. */
>> if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags)) {
>> + spin_lock(&idxd->dev_lock);
>> rc = idxd_device_config(idxd);
>> + spin_unlock(&idxd->dev_lock);
>> if (rc < 0) {
>> dev_err(dev, "HALT: %s config fails\n", idxd_name);
>> goto out;
>> diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
>> index 1107db3ce0a3a65246bd0d9b1f96e99c9fa3def6..74059fe43fafeb930f58db21d3824f62b095b968 100644
>> --- a/drivers/dma/idxd/irq.c
>> +++ b/drivers/dma/idxd/irq.c
>> @@ -36,7 +36,9 @@ static void idxd_device_reinit(struct work_struct *work)
>> int rc, i;
>>
>> idxd_device_reset(idxd);
>> + spin_lock(&idxd->dev_lock);
>> rc = idxd_device_config(idxd);
>> + spin_unlock(&idxd->dev_lock);
>> if (rc < 0)
>> goto out;
>>
>>
>
--
Vinicius
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