From: Alan Stern <stern@rowland.harvard.edu>
To: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc: Rhett Aultman <rhett.aultman@samsara.com>,
wg@grandegger.com, Marc Kleine-Budde <mkl@pengutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-can@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [RFC PATCH] USB: core: urb: add new transfer flag URB_FREE_COHERENT
Date: Sat, 4 Jun 2022 12:40:58 -0400 [thread overview]
Message-ID: <YpuLGkPcXrM+Eiwj@rowland.harvard.edu> (raw)
In-Reply-To: <20220604144157.208849-1-mailhol.vincent@wanadoo.fr>
On Sat, Jun 04, 2022 at 11:41:57PM +0900, Vincent Mailhol wrote:
> When allocating URB memory with kmalloc(), drivers can simply set the
> URB_FREE_BUFFER flag in urb::transfer_flags and that way, the memory
> will be freed in the background when calling killing the URB (for
> example with usb_kill_anchored_urbs()).
>
> However, there are no equivalent mechanism when allocating DMA memory
> (with usb_alloc_coherent()).
>
> This patch adds a new flag: URB_FREE_COHERENT. Setting this flag will
> cause the kernel to automatically call usb_free_coherent() when the
> URB is killed, similarly to how URB_FREE_BUFFER triggers a call to
> kfree().
>
> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> ---
> Hi Rhett Aultman,
>
> I put the code snippet I previously sent into a patch. It is not
> tested (this is why I post it as RFC). Please feel free to add this to
> your series.
> ---
> drivers/usb/core/urb.c | 3 +++
> include/linux/usb.h | 1 +
> 2 files changed, 4 insertions(+)
>
> diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> index 33d62d7e3929..1460fdac0b18 100644
> --- a/drivers/usb/core/urb.c
> +++ b/drivers/usb/core/urb.c
> @@ -22,6 +22,9 @@ static void urb_destroy(struct kref *kref)
>
> if (urb->transfer_flags & URB_FREE_BUFFER)
> kfree(urb->transfer_buffer);
> + else if (urb->transfer_flags & URB_FREE_COHERENT)
> + usb_free_coherent(urb->dev, urb->transfer_buffer_length,
> + urb->transfer_buffer, urb->transfer_dma);
>
> kfree(urb);
> }
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 60bee864d897..2200b3785fdb 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -1328,6 +1328,7 @@ extern int usb_disabled(void);
> #define URB_NO_INTERRUPT 0x0080 /* HINT: no non-error interrupt
> * needed */
> #define URB_FREE_BUFFER 0x0100 /* Free transfer buffer with the URB */
> +#define URB_FREE_COHERENT 0x0400 /* Free DMA memory of transfer buffer */
>
> /* The following flags are used internally by usbcore and HCDs */
> #define URB_DIR_IN 0x0200 /* Transfer from device to host */
I don't see anything wrong with this, except that it would be nice to keep
the flag values in numerical order. In other words, set URB_FREE_COHERENT
to 0x0200 and change URB_DIR_IN to 0x0400.
Alan Stern
next prev parent reply other threads:[~2022-06-04 16:41 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-03 19:52 [PATCH 001/001] can: gs_usb: gs_usb_open/close( ) fix memory leak Rhett Aultman
2022-06-04 2:11 ` [PATCH] " Vincent Mailhol
2022-06-04 2:26 ` Vincent MAILHOL
2022-06-04 14:08 ` Rhett Aultman
2022-06-04 14:41 ` [RFC PATCH] USB: core: urb: add new transfer flag URB_FREE_COHERENT Vincent Mailhol
2022-06-04 16:40 ` Alan Stern [this message]
2022-06-05 2:04 ` Vincent MAILHOL
2022-06-05 6:00 ` Oliver Neukum
2022-06-05 13:45 ` Vincent MAILHOL
2022-06-07 9:49 ` Oliver Neukum
2022-06-07 10:18 ` Vincent MAILHOL
2022-06-07 11:46 ` Oliver Neukum
2022-06-07 12:12 ` Vincent MAILHOL
2022-06-05 2:15 ` [RFC PATCH v2] usb: " Vincent Mailhol
2022-06-04 14:53 ` [PATCH] can: gs_usb: gs_usb_open/close( ) fix memory leak Vincent MAILHOL
2022-06-09 20:47 ` [PATCH v2 0/3] URB_FREE_COHERENT gs_usb memory leak fix Rhett Aultman
2022-06-09 20:47 ` [PATCH v2 1/3] drivers: usb/core/urb: Add URB_FREE_COHERENT Rhett Aultman
2022-06-10 0:18 ` Vincent MAILHOL
2022-06-10 10:46 ` Marc Kleine-Budde
2022-06-09 20:47 ` [PATCH v2 2/3] drivers: usb/core/urb: allow URB_FREE_COHERENT Rhett Aultman
2022-06-09 23:18 ` Vincent Mailhol
2022-06-09 20:47 ` [PATCH v2 3/3] can: gs_usb: fix DMA memory leak on close Rhett Aultman
2022-06-10 0:05 ` Vincent Mailhol
2022-06-10 1:28 ` Vincent Mailhol
2022-06-10 21:33 ` [PATCH v3 0/2] URB_FREE_COHERENT gs_usb memory leak fix Rhett Aultman
2022-06-10 21:33 ` [PATCH v3 1/2] drivers: usb/core/urb: Add URB_FREE_COHERENT Rhett Aultman
2022-06-11 15:31 ` Marc Kleine-Budde
2022-06-11 16:06 ` Vincent MAILHOL
2022-06-21 13:51 ` Greg Kroah-Hartman
2022-06-21 14:59 ` Vincent MAILHOL
2022-06-21 15:03 ` Greg Kroah-Hartman
2022-06-21 15:54 ` Vincent MAILHOL
2022-06-21 15:11 ` Alan Stern
2022-06-21 15:55 ` Vincent MAILHOL
2022-06-21 16:14 ` Alan Stern
2022-06-21 16:40 ` Vincent MAILHOL
2022-06-21 17:00 ` Greg Kroah-Hartman
2022-06-21 17:14 ` Vincent MAILHOL
2022-06-21 17:46 ` Greg Kroah-Hartman
2022-06-22 9:22 ` David Laight
2022-06-22 9:41 ` Greg Kroah-Hartman
2022-06-22 10:03 ` David Laight
2022-06-22 11:11 ` Oliver Neukum
2022-06-22 10:34 ` Vincent MAILHOL
2022-06-22 12:23 ` Greg Kroah-Hartman
2022-06-22 15:59 ` Vincent MAILHOL
2022-06-22 18:11 ` Rhett Aultman
2022-06-26 8:21 ` Vincent MAILHOL
2022-06-27 19:24 ` Rhett Aultman
2022-06-28 1:09 ` Vincent MAILHOL
2022-07-04 13:02 ` Marc Kleine-Budde
2022-07-04 15:35 ` Rhett Aultman
2022-07-05 7:50 ` Marc Kleine-Budde
2022-06-23 17:30 ` Hongren Zenithal Zheng
2022-06-23 17:45 ` Shuah Khan
2022-06-24 14:43 ` Alan Stern
2022-06-24 16:01 ` Hongren Zenithal Zheng
2022-06-24 16:31 ` Shuah Khan
2022-06-24 18:07 ` Alan Stern
2022-06-27 22:54 ` Shuah Khan
2022-06-28 1:35 ` Alan Stern
2022-07-01 2:10 ` Shuah Khan
2022-08-01 17:42 ` Shuah Khan
2022-08-01 18:28 ` Vincent MAILHOL
2022-08-03 23:44 ` Shuah Khan
2022-06-10 21:33 ` [PATCH v3 2/2] can: gs_usb: fix DMA memory leak on close Rhett Aultman
2022-06-11 15:35 ` Marc Kleine-Budde
2022-06-11 16:03 ` Vincent MAILHOL
2022-06-12 21:28 ` David Laight
2022-06-12 21:33 ` Marc Kleine-Budde
2022-06-14 15:26 ` [PATCH v4 0/1] URB_FREE_COHERENT gs_usb memory leak fix Rhett Aultman
2022-06-14 15:26 ` [PATCH v4 1/1] can: gs_usb: fix DMA memory leak on close Rhett Aultman
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