From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: john.hubbard@gmail.com To: Matthew Wilcox , Michal Hocko , Christopher Lameter , Jason Gunthorpe , Dan Williams , Jan Kara , Al Viro Cc: linux-mm@kvack.org, LKML , linux-rdma , linux-fsdevel@vger.kernel.org, John Hubbard Subject: [PATCH 1/4] mm: get_user_pages: consolidate error handling Date: Thu, 27 Sep 2018 22:39:46 -0700 Message-Id: <20180928053949.5381-2-jhubbard@nvidia.com> In-Reply-To: <20180928053949.5381-1-jhubbard@nvidia.com> References: <20180928053949.5381-1-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: From: John Hubbard An upcoming patch requires a way to operate on each page that any of the get_user_pages_*() variants returns. In preparation for that, consolidate the error handling for __get_user_pages(). This provides a single location (the "out:" label) for operating on the collected set of pages that are about to be returned. As long every use of the "ret" variable is being edited, rename "ret" --> "err", so that its name matches its true role. This also gets rid of two shadowed variable declarations, as a tiny beneficial a side effect. Reviewed-by: Jan Kara Signed-off-by: John Hubbard --- mm/gup.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 1abc8b4afff6..05ee7c18e59a 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -660,6 +660,7 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, struct vm_area_struct **vmas, int *nonblocking) { long i = 0; + int err = 0; unsigned int page_mask; struct vm_area_struct *vma = NULL; @@ -685,18 +686,19 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (!vma || start >= vma->vm_end) { vma = find_extend_vma(mm, start); if (!vma && in_gate_area(mm, start)) { - int ret; - ret = get_gate_page(mm, start & PAGE_MASK, + err = get_gate_page(mm, start & PAGE_MASK, gup_flags, &vma, pages ? &pages[i] : NULL); - if (ret) - return i ? : ret; + if (err) + goto out; page_mask = 0; goto next_page; } - if (!vma || check_vma_flags(vma, gup_flags)) - return i ? : -EFAULT; + if (!vma || check_vma_flags(vma, gup_flags)) { + err = -EFAULT; + goto out; + } if (is_vm_hugetlb_page(vma)) { i = follow_hugetlb_page(mm, vma, pages, vmas, &start, &nr_pages, i, @@ -709,23 +711,25 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, * If we have a pending SIGKILL, don't keep faulting pages and * potentially allocating memory. */ - if (unlikely(fatal_signal_pending(current))) - return i ? i : -ERESTARTSYS; + if (unlikely(fatal_signal_pending(current))) { + err = -ERESTARTSYS; + goto out; + } cond_resched(); page = follow_page_mask(vma, start, foll_flags, &page_mask); if (!page) { - int ret; - ret = faultin_page(tsk, vma, start, &foll_flags, + err = faultin_page(tsk, vma, start, &foll_flags, nonblocking); - switch (ret) { + switch (err) { case 0: goto retry; case -EFAULT: case -ENOMEM: case -EHWPOISON: - return i ? i : ret; + goto out; case -EBUSY: - return i; + err = 0; + goto out; case -ENOENT: goto next_page; } @@ -737,7 +741,8 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, */ goto next_page; } else if (IS_ERR(page)) { - return i ? i : PTR_ERR(page); + err = PTR_ERR(page); + goto out; } if (pages) { pages[i] = page; @@ -757,7 +762,9 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, start += page_increm * PAGE_SIZE; nr_pages -= page_increm; } while (nr_pages); - return i; + +out: + return i ? i : err; } static bool vma_permits_fault(struct vm_area_struct *vma, -- 2.19.0