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author | Frederic Weisbecker | 2009-10-18 01:09:09 +0200 |
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committer | Frederic Weisbecker | 2009-10-18 01:12:33 +0200 |
commit | 0f8f86c7bdd1c954fbe153af437a0d91a6c5721a (patch) | |
tree | 94a8d419a470a4f9852ca397bb9bbe48db92ff5c /drivers/usb/core/message.c | |
parent | Merge branch 'linus' into tracing/hw-breakpoints (diff) | |
parent | perf tools: Move dereference after NULL test (diff) | |
download | kernel-qcow2-linux-0f8f86c7bdd1c954fbe153af437a0d91a6c5721a.tar.gz kernel-qcow2-linux-0f8f86c7bdd1c954fbe153af437a0d91a6c5721a.tar.xz kernel-qcow2-linux-0f8f86c7bdd1c954fbe153af437a0d91a6c5721a.zip |
Merge commit 'perf/core' into perf/hw-breakpoint
Conflicts:
kernel/Makefile
kernel/trace/Makefile
kernel/trace/trace.h
samples/Makefile
Merge reason: We need to be uptodate with the perf events development
branch because we plan to rewrite the breakpoints API on top of
perf events.
Diffstat (limited to 'drivers/usb/core/message.c')
-rw-r--r-- | drivers/usb/core/message.c | 32 |
1 files changed, 10 insertions, 22 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 9720e699f472..da718e84d58d 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -459,35 +459,23 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev, io->urbs[i]->context = io; /* - * Some systems need to revert to PIO when DMA is - * temporarily unavailable. For their sakes, both - * transfer_buffer and transfer_dma are set when - * possible. However this can only work on systems - * without: + * Some systems need to revert to PIO when DMA is temporarily + * unavailable. For their sakes, both transfer_buffer and + * transfer_dma are set when possible. * - * - HIGHMEM, since DMA buffers located in high memory - * are not directly addressable by the CPU for PIO; - * - * - IOMMU, since dma_map_sg() is allowed to use an - * IOMMU to make virtually discontiguous buffers be - * "dma-contiguous" so that PIO and DMA need diferent - * numbers of URBs. - * - * So when HIGHMEM or IOMMU are in use, transfer_buffer - * is NULL to prevent stale pointers and to help spot - * bugs. + * Note that if IOMMU coalescing occurred, we cannot + * trust sg_page anymore, so check if S/G list shrunk. */ + if (io->nents == io->entries && !PageHighMem(sg_page(sg))) + io->urbs[i]->transfer_buffer = sg_virt(sg); + else + io->urbs[i]->transfer_buffer = NULL; + if (dma) { io->urbs[i]->transfer_dma = sg_dma_address(sg); len = sg_dma_len(sg); -#if defined(CONFIG_HIGHMEM) || defined(CONFIG_GART_IOMMU) - io->urbs[i]->transfer_buffer = NULL; -#else - io->urbs[i]->transfer_buffer = sg_virt(sg); -#endif } else { /* hc may use _only_ transfer_buffer */ - io->urbs[i]->transfer_buffer = sg_virt(sg); len = sg->length; } |