Am Montag, den 11.01.2021, 10:49 +0000 schrieb Bui Quang Minh:
> In mcba_usb_read_bulk_callback(), when we don't resubmit or fails to
> resubmit the urb, we need to deallocate the transfer buffer that is
> allocated in mcba_usb_start().
>
> Reported-by: [email protected]
> Signed-off-by: Bui Quang Minh <[email protected]>
> ---
> v1: add memory leak fix when not resubmitting urb
> v2: add memory leak fix when failing to resubmit urb
>
> drivers/net/can/usb/mcba_usb.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c
> index df54eb7d4b36..30236e640116 100644
> --- a/drivers/net/can/usb/mcba_usb.c
> +++ b/drivers/net/can/usb/mcba_usb.c
> @@ -584,6 +584,8 @@ static void mcba_usb_read_bulk_callback(struct urb *urb)
> case -EPIPE:
> case -EPROTO:
> case -ESHUTDOWN:
> + usb_free_coherent(urb->dev, urb->transfer_buffer_length,
> + urb->transfer_buffer, urb->transfer_dma);
> return;
>
Can you call usb_free_coherent() in what can be hard IRQ context?
Regards
Oliver
On Mon, Jan 11, 2021 at 01:00:31PM +0100, Oliver Neukum wrote:
> Am Montag, den 11.01.2021, 10:49 +0000 schrieb Bui Quang Minh:
> > In mcba_usb_read_bulk_callback(), when we don't resubmit or fails to
> > resubmit the urb, we need to deallocate the transfer buffer that is
> > allocated in mcba_usb_start().
> >
> > Reported-by: [email protected]
> > Signed-off-by: Bui Quang Minh <[email protected]>
> > ---
> > v1: add memory leak fix when not resubmitting urb
> > v2: add memory leak fix when failing to resubmit urb
> >
> > drivers/net/can/usb/mcba_usb.c | 11 ++++++++---
> > 1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c
> > index df54eb7d4b36..30236e640116 100644
> > --- a/drivers/net/can/usb/mcba_usb.c
> > +++ b/drivers/net/can/usb/mcba_usb.c
> > @@ -584,6 +584,8 @@ static void mcba_usb_read_bulk_callback(struct urb *urb)
> > case -EPIPE:
> > case -EPROTO:
> > case -ESHUTDOWN:
> > + usb_free_coherent(urb->dev, urb->transfer_buffer_length,
> > + urb->transfer_buffer, urb->transfer_dma);
> > return;
> >
>
> Can you call usb_free_coherent() in what can be hard IRQ context?
You are right, I digged in the code and saw some comments that on some
architectures, usb_free_coherent() cannot be called in hard IRQ context.
I see the usb_free_coherent() is called in write_bulk_callback too. I will
send a patch that uses usb_anchor to keep track of these urbs and cleanup
the transfer buffer later in disconnect().
Thank you for your review,
Quang Minh.
On Mon, Jan 11, 2021 at 9:31 PM Bui Quang Minh <[email protected]> wrote:
>
> On Mon, Jan 11, 2021 at 01:00:31PM +0100, Oliver Neukum wrote:
> > Am Montag, den 11.01.2021, 10:49 +0000 schrieb Bui Quang Minh:
> > > In mcba_usb_read_bulk_callback(), when we don't resubmit or fails to
> > > resubmit the urb, we need to deallocate the transfer buffer that is
> > > allocated in mcba_usb_start().
> > >
> > > Reported-by: [email protected]
> > > Signed-off-by: Bui Quang Minh <[email protected]>
> > > ---
> > > v1: add memory leak fix when not resubmitting urb
> > > v2: add memory leak fix when failing to resubmit urb
> > >
> > > drivers/net/can/usb/mcba_usb.c | 11 ++++++++---
> > > 1 file changed, 8 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c
> > > index df54eb7d4b36..30236e640116 100644
> > > --- a/drivers/net/can/usb/mcba_usb.c
> > > +++ b/drivers/net/can/usb/mcba_usb.c
> > > @@ -584,6 +584,8 @@ static void mcba_usb_read_bulk_callback(struct urb *urb)
> > > case -EPIPE:
> > > case -EPROTO:
> > > case -ESHUTDOWN:
> > > + usb_free_coherent(urb->dev, urb->transfer_buffer_length,
> > > + urb->transfer_buffer, urb->transfer_dma);
> > > return;
> > >
> >
> > Can you call usb_free_coherent() in what can be hard IRQ context?
>
> You are right, I digged in the code and saw some comments that on some
> architectures, usb_free_coherent() cannot be called in hard IRQ context.
> I see the usb_free_coherent() is called in write_bulk_callback too. I will
> send a patch that uses usb_anchor to keep track of these urbs and cleanup
> the transfer buffer later in disconnect().
Hi, I have sent a version 3 patch. However, I found out that usb_free_coherent()
is ok in this situation. In usb_free_coherent(), if the buffer is allocated via
dma_alloc_coherent() in usb_alloc_coherent(), dma_free_coherent() is called.
In dma_free_coherent(), ops->free() may be called in some cases which may
contains calls to vunmap() that is not permitted in interrupt context. However,
in usb_alloc_coherent(), buffer can be allocated from dma pool if the
size is less
than 2048 and the buffer size in mcba_usb is obviously less than 2048.
As a result,
usb_free_coherent() will at most fall in the path that calls
dma_pool_free(), which is
safe. Am I right?
Thanks,
Quang Minh.
On Tue, Jan 12, 2021 at 01:42:33PM +0700, Minh B?i Quang wrote:
> On Mon, Jan 11, 2021 at 9:31 PM Bui Quang Minh <[email protected]> wrote:
> >
> > On Mon, Jan 11, 2021 at 01:00:31PM +0100, Oliver Neukum wrote:
> > > Am Montag, den 11.01.2021, 10:49 +0000 schrieb Bui Quang Minh:
> > > > In mcba_usb_read_bulk_callback(), when we don't resubmit or fails to
> > > > resubmit the urb, we need to deallocate the transfer buffer that is
> > > > allocated in mcba_usb_start().
> > > >
> > > > Reported-by: [email protected]
> > > > Signed-off-by: Bui Quang Minh <[email protected]>
> > > > ---
> > > > v1: add memory leak fix when not resubmitting urb
> > > > v2: add memory leak fix when failing to resubmit urb
> > > >
> > > > drivers/net/can/usb/mcba_usb.c | 11 ++++++++---
> > > > 1 file changed, 8 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c
> > > > index df54eb7d4b36..30236e640116 100644
> > > > --- a/drivers/net/can/usb/mcba_usb.c
> > > > +++ b/drivers/net/can/usb/mcba_usb.c
> > > > @@ -584,6 +584,8 @@ static void mcba_usb_read_bulk_callback(struct urb *urb)
> > > > case -EPIPE:
> > > > case -EPROTO:
> > > > case -ESHUTDOWN:
> > > > + usb_free_coherent(urb->dev, urb->transfer_buffer_length,
> > > > + urb->transfer_buffer, urb->transfer_dma);
> > > > return;
> > > >
> > >
> > > Can you call usb_free_coherent() in what can be hard IRQ context?
> >
> > You are right, I digged in the code and saw some comments that on some
> > architectures, usb_free_coherent() cannot be called in hard IRQ context.
> > I see the usb_free_coherent() is called in write_bulk_callback too. I will
> > send a patch that uses usb_anchor to keep track of these urbs and cleanup
> > the transfer buffer later in disconnect().
>
> Hi, I have sent a version 3 patch. However, I found out that usb_free_coherent()
> is ok in this situation. In usb_free_coherent(), if the buffer is allocated via
> dma_alloc_coherent() in usb_alloc_coherent(), dma_free_coherent() is called.
> In dma_free_coherent(), ops->free() may be called in some cases which may
> contains calls to vunmap() that is not permitted in interrupt context. However,
> in usb_alloc_coherent(), buffer can be allocated from dma pool if the
> size is less
> than 2048 and the buffer size in mcba_usb is obviously less than 2048.
> As a result,
> usb_free_coherent() will at most fall in the path that calls
> dma_pool_free(), which is
> safe. Am I right?
Hi, I'm CC'ing CAN network driver maintainers so we can discuss the patch properly.
I'm so sorry for spamming emails.
Thanks,
Quang Minh.