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@xxxxxxxxxx> --- 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 */ -- 2.35.1
