Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758260AbZFCOYl (ORCPT ); Wed, 3 Jun 2009 10:24:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753407AbZFCOYe (ORCPT ); Wed, 3 Jun 2009 10:24:34 -0400 Received: from Mycroft.westnet.com ([216.187.52.7]:33950 "EHLO Mycroft.westnet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751826AbZFCOYd (ORCPT ); Wed, 3 Jun 2009 10:24:33 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18982.34690.977909.654562@stoffel.org> Date: Wed, 3 Jun 2009 10:24:02 -0400 From: "John Stoffel" To: Pete Zaitcev Cc: David , "John Stoffel" , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Subject: Re: Patch to fix usbmon crash on Opteron In-Reply-To: <20090602210932.b74fff08.zaitcev@redhat.com> References: <20090602210932.b74fff08.zaitcev@redhat.com> X-Mailer: VM 8.0.9 under Emacs 22.3.1 (i486-pc-linux-gnu) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 21879 Lines: 534 Pete> Here's my proposal: forget the clever-by-half tricks and simply Pete> use transfer_buffer. This should not only fix Opteron, but also Pete> future IOMMUs that Intel and AMD promise. It may also make Pete> usbmon useable on PPC at last. My crash was seen on an AMD Athlon X2 5200+ processor, where tcpdump would just completely hand the system. I'll apply this patch and see if I can replicate the error. Pete> I think downsides are negligible. The ones I see are: Pete> - A driver may pass an address of one buffer down as transfer_buffer, Pete> and entirely different entity mapped for DMA, resulting in misleading Pete> output of usbmon. Pete> - Out of tree drivers may crash usbmon if they store garbage in Pete> transfer_buffer. I went over the tree with a comb and fixed obvious Pete> bugs, and clarified the documentation in comments. Pete> - Drivers that use get_user_pages will not be possible to monitor Pete> - Similar deal is with usb_storage transferring from highmem, but Pete> it works fine on 64-bit systems, so I think it's not a concern. Pete> I'm adding a sign-off line in case, but in general this is a patch Pete> for testing. In particular, sisusb is a concern. Pete> David & John, I am quite certain that your Opterons will not Pete> crash now, but please give it a try, and also you can use this Pete> code to produce usbmon traces you needed for debugging of other Pete> things. Pete> Signed-off-by: Pete Zaitcev Pete> diff --git a/drivers/staging/rspiusb/rspiusb.c b/drivers/staging/rspiusb/rspiusb.c Pete> index ecaffb5..fe97451 100644 Pete> --- a/drivers/staging/rspiusb/rspiusb.c Pete> +++ b/drivers/staging/rspiusb/rspiusb.c Pete> @@ -432,8 +432,7 @@ static void piusb_write_bulk_callback(struct urb *urb) Pete> __func__, status); pdx-> pendingWrite = 0; Pete> - usb_buffer_free(urb->dev, urb->transfer_buffer_length, Pete> - urb->transfer_buffer, urb->transfer_dma); Pete> + kfree(urb->transfer_buffer); Pete> } Pete> int piusb_output(struct ioctl_struct * io, unsigned char *uBuf, int len, Pete> @@ -445,9 +444,7 @@ int piusb_output(struct ioctl_struct * io, unsigned char *uBuf, int len, Pete> urb = usb_alloc_urb(0, GFP_KERNEL); Pete> if (urb != NULL) { Pete> - kbuf = Pete> - usb_buffer_alloc(pdx->udev, len, GFP_KERNEL, Pete> - &urb->transfer_dma); Pete> + kbuf = kmalloc(len, GFP_KERNEL); Pete> if (!kbuf) { Pete> info("buffer_alloc failed\n"); Pete> return -ENOMEM; Pete> @@ -455,7 +452,6 @@ int piusb_output(struct ioctl_struct * io, unsigned char *uBuf, int len, Pete> memcpy(kbuf, uBuf, len); Pete> usb_fill_bulk_urb(urb, pdx->udev, pdx->hEP[io->endpoint], kbuf, Pete> len, piusb_write_bulk_callback, pdx); Pete> - urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; Pete> err = usb_submit_urb(urb, GFP_KERNEL); Pete> if (err) { Pete> dev_err(&pdx->udev->dev, Pete> @@ -617,7 +613,7 @@ static int MapUserBuffer(struct ioctl_struct *io, struct device_extension *pdx) Pete> numPagesRequired = Pete> ((uaddr & ~PAGE_MASK) + count + ~PAGE_MASK) >> PAGE_SHIFT; Pete> dbg("Number of pages needed = %d", numPagesRequired); Pete> - maplist_p = vmalloc(numPagesRequired * sizeof(struct page)); //, GFP_ATOMIC); Pete> + maplist_p = vmalloc(numPagesRequired * sizeof(struct page *)); //, GFP_ATOMIC); Pete> if (!maplist_p) { Pete> dbg("Can't Allocate Memory for maplist_p"); Pete> return -ENOMEM; Pete> @@ -681,9 +677,7 @@ static int MapUserBuffer(struct ioctl_struct *io, struct device_extension *pdx) Pete> usb_fill_bulk_urb(pdx->PixelUrb[frameInfo][i], pdx-> udev, Pete> epAddr, Pete> - (dma_addr_t *) sg_dma_address(&pdx-> Pete> - sgl[frameInfo] Pete> - [i]), Pete> + NULL, // non-DMA HC? buy a better hardware Pete> sg_dma_len(&pdx->sgl[frameInfo][i]), Pete> piusb_readPIXEL_callback, (void *)pdx); pdx-> PixelUrb[frameInfo][i]->transfer_dma = Pete> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c Pete> index be86ae3..8fb176f 100644 Pete> --- a/drivers/usb/core/hub.c Pete> +++ b/drivers/usb/core/hub.c Pete> @@ -1070,7 +1070,7 @@ static int hub_configure(struct usb_hub *hub, Pete> goto fail; Pete> } Pete> - usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq, Pete> + usb_fill_int_urb(hub->urb, hdev, pipe, hub->buffer, maxp, hub_irq, Pete> hub, endpoint->bInterval); hub-> urb->transfer_dma = hub->buffer_dma; hub-> urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; Pete> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c Pete> index b626283..f06d095 100644 Pete> --- a/drivers/usb/core/message.c Pete> +++ b/drivers/usb/core/message.c Pete> @@ -421,30 +421,18 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev, Pete> /* Pete> * Some systems need to revert to PIO when DMA is temporarily Pete> * unavailable. For their sakes, both transfer_buffer and Pete> - * transfer_dma are set when possible. However this can only Pete> - * work on systems without: Pete> - * Pete> - * - HIGHMEM, since DMA buffers located in high memory are Pete> - * not directly addressable by the CPU for PIO; Pete> - * Pete> - * - IOMMU, since dma_map_sg() is allowed to use an IOMMU to Pete> - * make virtually discontiguous buffers be "dma-contiguous" Pete> - * so that PIO and DMA need diferent numbers of URBs. Pete> - * Pete> - * So when HIGHMEM or IOMMU are in use, transfer_buffer is NULL Pete> - * to prevent stale pointers and to help spot bugs. Pete> + * transfer_dma are set when possible. Pete> */ Pete> + if (PageHighMem(sg_page(sg))) { Pete> + io->urbs[i]->transfer_buffer = NULL; Pete> + } else { Pete> + io->urbs[i]->transfer_buffer = sg_virt(sg); Pete> + } Pete> if (dma) { io-> urbs[i]->transfer_dma = sg_dma_address(sg); Pete> len = sg_dma_len(sg); Pete> -#if defined(CONFIG_HIGHMEM) || defined(CONFIG_GART_IOMMU) Pete> - io->urbs[i]->transfer_buffer = NULL; Pete> -#else Pete> - io->urbs[i]->transfer_buffer = sg_virt(sg); Pete> -#endif Pete> } else { Pete> /* hc may use _only_ transfer_buffer */ Pete> - io->urbs[i]->transfer_buffer = sg_virt(sg); Pete> len = sg->length; Pete> } Pete> diff --git a/drivers/usb/misc/sisusbvga/sisusb.c b/drivers/usb/misc/sisusbvga/sisusb.c Pete> index b4ec716..0025847 100644 Pete> --- a/drivers/usb/misc/sisusbvga/sisusb.c Pete> +++ b/drivers/usb/misc/sisusbvga/sisusb.c Pete> @@ -79,14 +79,12 @@ sisusb_free_buffers(struct sisusb_usb_data *sisusb) Pete> for (i = 0; i < NUMOBUFS; i++) { Pete> if (sisusb->obuf[i]) { Pete> - usb_buffer_free(sisusb->sisusb_dev, sisusb->obufsize, Pete> - sisusb->obuf[i], sisusb->transfer_dma_out[i]); Pete> + kfree(sisusb->obuf[i]); sisusb-> obuf[i] = NULL; Pete> } Pete> } Pete> if (sisusb->ibuf) { Pete> - usb_buffer_free(sisusb->sisusb_dev, sisusb->ibufsize, Pete> - sisusb->ibuf, sisusb->transfer_dma_in); Pete> + kfree(sisusb->ibuf); sisusb-> ibuf = NULL; Pete> } Pete> } Pete> @@ -230,8 +228,7 @@ sisusb_bulk_completeout(struct urb *urb) Pete> static int Pete> sisusb_bulkout_msg(struct sisusb_usb_data *sisusb, int index, unsigned int pipe, void *data, Pete> - int len, int *actual_length, int timeout, unsigned int tflags, Pete> - dma_addr_t transfer_dma) Pete> + int len, int *actual_length, int timeout, unsigned int tflags) Pete> { Pete> struct urb *urb = sisusb->sisurbout[index]; Pete> int retval, byteswritten = 0; Pete> @@ -245,9 +242,6 @@ sisusb_bulkout_msg(struct sisusb_usb_data *sisusb, int index, unsigned int pipe, urb-> transfer_flags |= tflags; urb-> actual_length = 0; Pete> - if ((urb->transfer_dma = transfer_dma)) Pete> - urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; Pete> - Pete> /* Set up context */ sisusb-> urbout_context[index].actual_length = (timeout) ? Pete> NULL : actual_length; Pete> @@ -297,8 +291,8 @@ sisusb_bulk_completein(struct urb *urb) Pete> } Pete> static int Pete> -sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data, int len, Pete> - int *actual_length, int timeout, unsigned int tflags, dma_addr_t transfer_dma) Pete> +sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data, Pete> + int len, int *actual_length, int timeout, unsigned int tflags) Pete> { Pete> struct urb *urb = sisusb->sisurbin; Pete> int retval, readbytes = 0; Pete> @@ -311,9 +305,6 @@ sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data, urb-> transfer_flags |= tflags; urb-> actual_length = 0; Pete> - if ((urb->transfer_dma = transfer_dma)) Pete> - urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; Pete> - sisusb-> completein = 0; Pete> retval = usb_submit_urb(urb, GFP_ATOMIC); Pete> if (retval == 0) { Pete> @@ -422,8 +413,7 @@ static int sisusb_send_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len, Pete> thispass, Pete> &transferred_len, Pete> async ? 0 : 5 * HZ, Pete> - tflags, Pete> - sisusb->transfer_dma_out[index]); Pete> + tflags); Pete> if (result == -ETIMEDOUT) { Pete> @@ -432,29 +422,16 @@ static int sisusb_send_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len, Pete> return -ETIME; Pete> continue; Pete> + } Pete> - } else if ((result == 0) && !async && transferred_len) { Pete> + if ((result == 0) && !async && transferred_len) { Pete> thispass -= transferred_len; Pete> - if (thispass) { Pete> - if (sisusb->transfer_dma_out) { Pete> - /* If DMA, copy remaining Pete> - * to beginning of buffer Pete> - */ Pete> - memcpy(buffer, Pete> - buffer + transferred_len, Pete> - thispass); Pete> - } else { Pete> - /* If not DMA, simply increase Pete> - * the pointer Pete> - */ Pete> - buffer += transferred_len; Pete> - } Pete> - } Pete> + buffer += transferred_len; Pete> } else Pete> break; Pete> - }; Pete> + } Pete> if (result) Pete> return result; Pete> @@ -530,8 +507,7 @@ static int sisusb_recv_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len, Pete> thispass, Pete> &transferred_len, Pete> 5 * HZ, Pete> - tflags, Pete> - sisusb->transfer_dma_in); Pete> + tflags); Pete> if (transferred_len) Pete> thispass = transferred_len; Pete> @@ -3132,8 +3108,7 @@ static int sisusb_probe(struct usb_interface *intf, Pete> /* Allocate buffers */ sisusb-> ibufsize = SISUSB_IBUF_SIZE; Pete> - if (!(sisusb->ibuf = usb_buffer_alloc(dev, SISUSB_IBUF_SIZE, Pete> - GFP_KERNEL, &sisusb->transfer_dma_in))) { Pete> + if (!(sisusb->ibuf = kmalloc(SISUSB_IBUF_SIZE, GFP_KERNEL))) { Pete> dev_err(&sisusb->sisusb_dev->dev, "Failed to allocate memory for input buffer"); Pete> retval = -ENOMEM; Pete> goto error_2; Pete> @@ -3142,9 +3117,7 @@ static int sisusb_probe(struct usb_interface *intf, sisusb-> numobufs = 0; sisusb-> obufsize = SISUSB_OBUF_SIZE; Pete> for (i = 0; i < NUMOBUFS; i++) { Pete> - if (!(sisusb->obuf[i] = usb_buffer_alloc(dev, SISUSB_OBUF_SIZE, Pete> - GFP_KERNEL, Pete> - &sisusb->transfer_dma_out[i]))) { Pete> + if (!(sisusb->obuf[i] = kmalloc(SISUSB_OBUF_SIZE, GFP_KERNEL))) { Pete> if (i == 0) { Pete> dev_err(&sisusb->sisusb_dev->dev, "Failed to allocate memory for output buffer\n"); Pete> retval = -ENOMEM; Pete> diff --git a/drivers/usb/misc/sisusbvga/sisusb.h b/drivers/usb/misc/sisusbvga/sisusb.h Pete> index cf0b4a5..55492a5 100644 Pete> --- a/drivers/usb/misc/sisusbvga/sisusb.h Pete> +++ b/drivers/usb/misc/sisusbvga/sisusb.h Pete> @@ -123,8 +123,6 @@ struct sisusb_usb_data { Pete> int numobufs; /* number of obufs = number of out urbs */ Pete> char *obuf[NUMOBUFS], *ibuf; /* transfer buffers */ Pete> int obufsize, ibufsize; Pete> - dma_addr_t transfer_dma_out[NUMOBUFS]; Pete> - dma_addr_t transfer_dma_in; Pete> struct urb *sisurbout[NUMOBUFS]; Pete> struct urb *sisurbin; Pete> unsigned char urbstatus[NUMOBUFS]; Pete> diff --git a/drivers/usb/mon/Makefile b/drivers/usb/mon/Makefile Pete> index c6516b5..384b198 100644 Pete> --- a/drivers/usb/mon/Makefile Pete> +++ b/drivers/usb/mon/Makefile Pete> @@ -2,6 +2,6 @@ Pete> # Makefile for USB monitor Pete> # Pete> -usbmon-objs := mon_main.o mon_stat.o mon_text.o mon_bin.o mon_dma.o Pete> +usbmon-objs := mon_main.o mon_stat.o mon_text.o mon_bin.o Pete> obj-$(CONFIG_USB_MON) += usbmon.o Pete> diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c Pete> index 2efdf44..ef4b322 100644 Pete> --- a/drivers/usb/mon/mon_bin.c Pete> +++ b/drivers/usb/mon/mon_bin.c Pete> @@ -220,9 +220,8 @@ static void mon_free_buff(struct mon_pgmap *map, int npages); Pete> /* Pete> * This is a "chunked memcpy". It does not manipulate any counters. Pete> - * But it returns the new offset for repeated application. Pete> */ Pete> -unsigned int mon_copy_to_buff(const struct mon_reader_bin *this, Pete> +static void mon_copy_to_buff(const struct mon_reader_bin *this, Pete> unsigned int off, const unsigned char *from, unsigned int length) Pete> { Pete> unsigned int step_len; Pete> @@ -247,7 +246,6 @@ unsigned int mon_copy_to_buff(const struct mon_reader_bin *this, Pete> from += step_len; Pete> length -= step_len; Pete> } Pete> - return off; Pete> } Pete> /* Pete> @@ -400,15 +398,8 @@ static char mon_bin_get_data(const struct mon_reader_bin *rp, Pete> unsigned int offset, struct urb *urb, unsigned int length) Pete> { Pete> - if (urb->dev->bus->uses_dma && Pete> - (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) { Pete> - mon_dmapeek_vec(rp, offset, urb->transfer_dma, length); Pete> - return 0; Pete> - } Pete> - Pete> if (urb->transfer_buffer == NULL) Pete> return 'Z'; Pete> - Pete> mon_copy_to_buff(rp, offset, urb->transfer_buffer, length); Pete> return 0; Pete> } Pete> diff --git a/drivers/usb/mon/mon_dma.c b/drivers/usb/mon/mon_dma.c Pete> deleted file mode 100644 Pete> index 140cc80..0000000 Pete> --- a/drivers/usb/mon/mon_dma.c Pete> +++ /dev/null Pete> @@ -1,95 +0,0 @@ Pete> -/* Pete> - * The USB Monitor, inspired by Dave Harding's USBMon. Pete> - * Pete> - * mon_dma.c: Library which snoops on DMA areas. Pete> - * Pete> - * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com) Pete> - */ Pete> -#include Pete> -#include Pete> -#include Pete> -#include Pete> - Pete> -#include /* Only needed for declarations in usb_mon.h */ Pete> -#include "usb_mon.h" Pete> - Pete> -/* Pete> - * PC-compatibles, are, fortunately, sufficiently cache-coherent for this. Pete> - */ Pete> -#if defined(__i386__) || defined(__x86_64__) /* CONFIG_ARCH_I386 doesn't exit */ Pete> -#define MON_HAS_UNMAP 1 Pete> - Pete> -#define phys_to_page(phys) pfn_to_page((phys) >> PAGE_SHIFT) Pete> - Pete> -char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len) Pete> -{ Pete> - struct page *pg; Pete> - unsigned long flags; Pete> - unsigned char *map; Pete> - unsigned char *ptr; Pete> - Pete> - /* Pete> - * On i386, a DMA handle is the "physical" address of a page. Pete> - * In other words, the bus address is equal to physical address. Pete> - * There is no IOMMU. Pete> - */ Pete> - pg = phys_to_page(dma_addr); Pete> - Pete> - /* Pete> - * We are called from hardware IRQs in case of callbacks. Pete> - * But we can be called from softirq or process context in case Pete> - * of submissions. In such case, we need to protect KM_IRQ0. Pete> - */ Pete> - local_irq_save(flags); Pete> - map = kmap_atomic(pg, KM_IRQ0); Pete> - ptr = map + (dma_addr & (PAGE_SIZE-1)); Pete> - memcpy(dst, ptr, len); Pete> - kunmap_atomic(map, KM_IRQ0); Pete> - local_irq_restore(flags); Pete> - return 0; Pete> -} Pete> - Pete> -void mon_dmapeek_vec(const struct mon_reader_bin *rp, Pete> - unsigned int offset, dma_addr_t dma_addr, unsigned int length) Pete> -{ Pete> - unsigned long flags; Pete> - unsigned int step_len; Pete> - struct page *pg; Pete> - unsigned char *map; Pete> - unsigned long page_off, page_len; Pete> - Pete> - local_irq_save(flags); Pete> - while (length) { Pete> - /* compute number of bytes we are going to copy in this page */ Pete> - step_len = length; Pete> - page_off = dma_addr & (PAGE_SIZE-1); Pete> - page_len = PAGE_SIZE - page_off; Pete> - if (page_len < step_len) Pete> - step_len = page_len; Pete> - Pete> - /* copy data and advance pointers */ Pete> - pg = phys_to_page(dma_addr); Pete> - map = kmap_atomic(pg, KM_IRQ0); Pete> - offset = mon_copy_to_buff(rp, offset, map + page_off, step_len); Pete> - kunmap_atomic(map, KM_IRQ0); Pete> - dma_addr += step_len; Pete> - length -= step_len; Pete> - } Pete> - local_irq_restore(flags); Pete> -} Pete> - Pete> -#endif /* __i386__ */ Pete> - Pete> -#ifndef MON_HAS_UNMAP Pete> -char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len) Pete> -{ Pete> - return 'D'; Pete> -} Pete> - Pete> -void mon_dmapeek_vec(const struct mon_reader_bin *rp, Pete> - unsigned int offset, dma_addr_t dma_addr, unsigned int length) Pete> -{ Pete> - ; Pete> -} Pete> - Pete> -#endif /* MON_HAS_UNMAP */ Pete> diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c Pete> index 1f71543..56bb62f 100644 Pete> --- a/drivers/usb/mon/mon_text.c Pete> +++ b/drivers/usb/mon/mon_text.c Pete> @@ -150,20 +150,6 @@ static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb, Pete> return '>'; Pete> } Pete> - /* Pete> - * The check to see if it's safe to poke at data has an enormous Pete> - * number of corner cases, but it seems that the following is Pete> - * more or less safe. Pete> - * Pete> - * We do not even try to look at transfer_buffer, because it can Pete> - * contain non-NULL garbage in case the upper level promised to Pete> - * set DMA for the HCD. Pete> - */ Pete> - if (urb->dev->bus->uses_dma && Pete> - (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) { Pete> - return mon_dmapeek(ep->data, urb->transfer_dma, len); Pete> - } Pete> - Pete> if (urb->transfer_buffer == NULL) Pete> return 'Z'; /* '0' would be not as pretty. */ Pete> diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h Pete> index f5d84ff..df9a4df 100644 Pete> --- a/drivers/usb/mon/usb_mon.h Pete> +++ b/drivers/usb/mon/usb_mon.h Pete> @@ -65,20 +65,6 @@ int __init mon_bin_init(void); Pete> void mon_bin_exit(void); Pete> /* Pete> - * DMA interface. Pete> - * Pete> - * XXX The vectored side needs a serious re-thinking. Abstracting vectors, Pete> - * like in Paolo's original patch, produces a double pkmap. We need an idea. Pete> -*/ Pete> -extern char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len); Pete> - Pete> -struct mon_reader_bin; Pete> -extern void mon_dmapeek_vec(const struct mon_reader_bin *rp, Pete> - unsigned int offset, dma_addr_t dma_addr, unsigned int len); Pete> -extern unsigned int mon_copy_to_buff(const struct mon_reader_bin *rp, Pete> - unsigned int offset, const unsigned char *from, unsigned int len); Pete> - Pete> -/* Pete> */ Pete> extern struct mutex mon_lock; Pete> diff --git a/include/linux/usb.h b/include/linux/usb.h Pete> index 3aa2cd1..5b58d89 100644 Pete> --- a/include/linux/usb.h Pete> +++ b/include/linux/usb.h Pete> @@ -1014,9 +1014,10 @@ typedef void (*usb_complete_t)(struct urb *); Pete> * @transfer_flags: A variety of flags may be used to affect how URB Pete> * submission, unlinking, or operation are handled. Different Pete> * kinds of URB can use different flags. Pete> - * @transfer_buffer: This identifies the buffer to (or from) which Pete> - * the I/O request will be performed (unless URB_NO_TRANSFER_DMA_MAP Pete> - * is set). This buffer must be suitable for DMA; allocate it with Pete> + * @transfer_buffer: This identifies the buffer to (or from) which the I/O Pete> + * request will be performed unless URB_NO_TRANSFER_DMA_MAP is set Pete> + * (however, do not leave garbage in transfer_buffer even then). Pete> + * This buffer must be suitable for DMA; allocate it with Pete> * kmalloc() or equivalent. For transfers to "in" endpoints, contents Pete> * of this buffer will be modified. This buffer is used for the data Pete> * stage of control transfers. Pete> @@ -1078,9 +1079,15 @@ typedef void (*usb_complete_t)(struct urb *); Pete> * allocate a DMA buffer with usb_buffer_alloc() or call usb_buffer_map(). Pete> * When these transfer flags are provided, host controller drivers will Pete> * attempt to use the dma addresses found in the transfer_dma and/or Pete> - * setup_dma fields rather than determining a dma address themselves. (Note Pete> - * that transfer_buffer and setup_packet must still be set because not all Pete> - * host controllers use DMA, nor do virtual root hubs). Pete> + * setup_dma fields rather than determining a dma address themselves. Pete> + * Pete> + * Note that transfer_buffer must still be set if the controller Pete> + * does not support DMA (as indicated by bus.uses_dma) and when talking Pete> + * to root hub. If you have to trasfer between highmem zone and the device Pete> + * on such controller, create a bounce buffer or bail out with an error. Pete> + * If transfer_buffer cannot be set (is in highmem) and the controller is DMA Pete> + * capable, assign NULL to it, so that usbmon knows not to use the value. Pete> + * The setup_packet must always be set, so it cannot be located in highmem. Pete> * Pete> * Initialization: Pete> * Pete> -- Pete -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/