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Date: Thu, 25 Jun 2009 11:58:55 +0200 From: Peter Zijlstra <peterz@...radead.org> To: "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Linus Torvalds <torvalds@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>, Darren Hart <dvhltc@...ibm.com> Subject: [PATCH] clarify get_user_pages() prototype On Thu, 2009-06-25 at 10:43 +0800, Zhang, Yanmin wrote: > > +static int fault_in_user_writeable(u32 __user *uaddr) > > +{ > > + int ret = get_user_pages(current, current->mm, (unsigned long)uaddr, > > + sizeof(*uaddr), 1, 0, NULL, NULL); > The 4th parameter of get_user_pages means page number. sizeof(*uaddr) is equal to > 4, so you want 4 pages? crap... that's what you get for only looking at the prototype :/ --- Subject: clarify get_user_pages() prototype Currently the 4th parameter of get_user_pages() is called len, but its in pages, not bytes. Rename the thing to nr_pages to avoid future confusion. Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> --- include/linux/mm.h | 2 +- mm/memory.c | 26 ++++++++++++-------------- mm/nommu.c | 12 +++++------- 3 files changed, 18 insertions(+), 22 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index d006e93..ba3a7cb 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -826,7 +826,7 @@ extern int make_pages_present(unsigned long addr, unsigned long end); extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, int len, int write, int force, + unsigned long start, int nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas); int get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages); diff --git a/mm/memory.c b/mm/memory.c index f46ac18..6521619 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1207,8 +1207,8 @@ static inline int use_zero_page(struct vm_area_struct *vma) int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, int len, int flags, - struct page **pages, struct vm_area_struct **vmas) + unsigned long start, int nr_pages, int flags, + struct page **pages, struct vm_area_struct **vmas) { int i; unsigned int vm_flags = 0; @@ -1217,7 +1217,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS); int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL); - if (len <= 0) + if (nr_pages <= 0) return 0; /* * Require read or write permissions. @@ -1269,7 +1269,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, vmas[i] = gate_vma; i++; start += PAGE_SIZE; - len--; + nr_pages--; continue; } @@ -1280,7 +1280,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (is_vm_hugetlb_page(vma)) { i = follow_hugetlb_page(mm, vma, pages, vmas, - &start, &len, i, write); + &start, &nr_pages, i, write); continue; } @@ -1357,9 +1357,9 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, vmas[i] = vma; i++; start += PAGE_SIZE; - len--; - } while (len && start < vma->vm_end); - } while (len); + nr_pages--; + } while (nr_pages && start < vma->vm_end); + } while (nr_pages); return i; } @@ -1368,7 +1368,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, * @tsk: task_struct of target task * @mm: mm_struct of target mm * @start: starting user address - * @len: number of pages from start to pin + * @nr_pages: number of pages from start to pin * @write: whether pages will be written to by the caller * @force: whether to force write access even if user mapping is * readonly. This will result in the page being COWed even @@ -1380,7 +1380,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, * Or NULL if the caller does not require them. * * Returns number of pages pinned. This may be fewer than the number - * requested. If len is 0 or negative, returns 0. If no pages + * requested. If nr_pages is 0 or negative, returns 0. If no pages * were pinned, returns -errno. Each page returned must be released * with a put_page() call when it is finished with. vmas will only * remain valid while mmap_sem is held. @@ -1414,7 +1414,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, * See also get_user_pages_fast, for performance critical applications. */ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, int len, int write, int force, + unsigned long start, int nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas) { int flags = 0; @@ -1424,9 +1424,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (force) flags |= GUP_FLAGS_FORCE; - return __get_user_pages(tsk, mm, - start, len, flags, - pages, vmas); + return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); } EXPORT_SYMBOL(get_user_pages); diff --git a/mm/nommu.c b/mm/nommu.c index 2fd2ad5..bf0cc76 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -173,8 +173,8 @@ unsigned int kobjsize(const void *objp) } int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, int len, int flags, - struct page **pages, struct vm_area_struct **vmas) + unsigned long start, int nr_pages, int flags, + struct page **pages, struct vm_area_struct **vmas) { struct vm_area_struct *vma; unsigned long vm_flags; @@ -189,7 +189,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); - for (i = 0; i < len; i++) { + for (i = 0; i < nr_pages; i++) { vma = find_vma(mm, start); if (!vma) goto finish_or_fault; @@ -224,7 +224,7 @@ finish_or_fault: * - don't permit access to VMAs that don't support it, such as I/O mappings */ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, int len, int write, int force, + unsigned long start, int nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas) { int flags = 0; @@ -234,9 +234,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (force) flags |= GUP_FLAGS_FORCE; - return __get_user_pages(tsk, mm, - start, len, flags, - pages, vmas); + return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); } EXPORT_SYMBOL(get_user_pages); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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