Messages in this thread Patch in this message |  | | | From | KOSAKI Motohiro <> | | Subject | [RFC][PATCH v3 6/6] fix wrong get_user_pages usage in iovlock.c | | Date | Tue, 14 Apr 2009 15:23:13 +0900 (JST) |
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I don't have NET-DMA usable device. I hope to get expert review.
========================= Subject: [Untested][RFC][PATCH] fix wrong get_user_pages usage in iovlock.c down_read(mmap_sem) get_user_pages() up_read(mmap_sem)
is fork unsafe. fix it.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Maciej Sosnowski <maciej.sosnowski@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chris Leech <christopher.leech@intel.com> Cc: netdev@vger.kernel.org --- drivers/dma/iovlock.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) Index: b/drivers/dma/iovlock.c =================================================================== --- a/drivers/dma/iovlock.c 2009-02-21 16:53:23.000000000 +0900 +++ b/drivers/dma/iovlock.c 2009-04-13 04:46:02.000000000 +0900 @@ -94,18 +94,10 @@ struct dma_pinned_list *dma_pin_iovec_pa pages += page_list->nr_pages; /* pin pages down */ - down_read(¤t->mm->mmap_sem); - ret = get_user_pages( - current, - current->mm, - (unsigned long) iov[i].iov_base, - page_list->nr_pages, - 1, /* write */ - 0, /* force */ - page_list->pages, - NULL); - up_read(¤t->mm->mmap_sem); - + down_read(¤t->mm->mm_pinned_sem); + ret = get_user_pages_fast((unsigned long) iov[i].iov_base, + page_list->nr_pages, 1, + page_list->pages); if (ret != page_list->nr_pages) goto unpin; @@ -127,6 +119,8 @@ void dma_unpin_iovec_pages(struct dma_pi if (!pinned_list) return; + up_read(¤t->mm->mm_pinned_sem); + for (i = 0; i < pinned_list->nr_iovecs; i++) { struct dma_page_list *page_list = &pinned_list->page_list[i]; for (j = 0; j < page_list->nr_pages; j++) {
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