[PATCH 23/26] ib: Convert qib_get_user_pages() to get_user_pages_unlocked()

[Jan Kara]

Convert qib_get_user_pages() to use get_user_pages_unlocked().  This
shortens the section where we hold mmap_sem for writing and also removes
the knowledge about get_user_pages() locking from ipath driver. We also
fix a bug in testing pinned number of pages when changing the code.

CC: Mike Marciniszyn <infinipath@xxxxxxxxx>
CC: Roland Dreier <roland@xxxxxxxxxx>
CC: linux-rdma@xxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 drivers/infiniband/hw/qib/qib_user_pages.c | 62 +++++++++++++-----------------
 1 file changed, 26 insertions(+), 36 deletions(-)

diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c
index 2bc1d2b96298..57ce83c2d1d9 100644
--- a/drivers/infiniband/hw/qib/qib_user_pages.c
+++ b/drivers/infiniband/hw/qib/qib_user_pages.c
@@ -48,39 +48,55 @@ static void __qib_release_user_pages(struct page **p, size_t num_pages,
 	}
 }
 
-/*
- * Call with current->mm->mmap_sem held.
+/**
+ * qib_get_user_pages - lock user pages into memory
+ * @start_page: the start page
+ * @num_pages: the number of pages
+ * @p: the output page structures
+ *
+ * This function takes a given start page (page aligned user virtual
+ * address) and pins it and the following specified number of pages.  For
+ * now, num_pages is always 1, but that will probably change at some point
+ * (because caller is doing expected sends on a single virtually contiguous
+ * buffer, so we can do all pages at once).
  */
-static int __qib_get_user_pages(unsigned long start_page, size_t num_pages,
-				struct page **p, struct vm_area_struct **vma)
+int qib_get_user_pages(unsigned long start_page, size_t num_pages,
+		       struct page **p)
 {
 	unsigned long lock_limit;
 	size_t got;
 	int ret;
+	struct mm_struct *mm = current->mm;
 
+	down_write(&mm->mmap_sem);
 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 
-	if (num_pages > lock_limit && !capable(CAP_IPC_LOCK)) {
+	if (mm->pinned_vm + num_pages > lock_limit && !capable(CAP_IPC_LOCK)) {
+		up_write(&mm->mmap_sem);
 		ret = -ENOMEM;
 		goto bail;
 	}
+	mm->pinned_vm += num_pages;
+	up_write(&mm->mmap_sem);
 
 	for (got = 0; got < num_pages; got += ret) {
-		ret = get_user_pages(current, current->mm,
-				     start_page + got * PAGE_SIZE,
-				     num_pages - got, 1, 1,
-				     p + got, vma);
+		ret = get_user_pages_unlocked(current, mm,
+					      start_page + got * PAGE_SIZE,
+					      num_pages - got, 1, 1,
+					      p + got);
 		if (ret < 0)
 			goto bail_release;
 	}
 
-	current->mm->pinned_vm += num_pages;
 
 	ret = 0;
 	goto bail;
 
 bail_release:
 	__qib_release_user_pages(p, got, 0);
+	down_write(&mm->mmap_sem);
+	mm->pinned_vm -= num_pages;
+	up_write(&mm->mmap_sem);
 bail:
 	return ret;
 }
@@ -117,32 +133,6 @@ dma_addr_t qib_map_page(struct pci_dev *hwdev, struct page *page,
 	return phys;
 }
 
-/**
- * qib_get_user_pages - lock user pages into memory
- * @start_page: the start page
- * @num_pages: the number of pages
- * @p: the output page structures
- *
- * This function takes a given start page (page aligned user virtual
- * address) and pins it and the following specified number of pages.  For
- * now, num_pages is always 1, but that will probably change at some point
- * (because caller is doing expected sends on a single virtually contiguous
- * buffer, so we can do all pages at once).
- */
-int qib_get_user_pages(unsigned long start_page, size_t num_pages,
-		       struct page **p)
-{
-	int ret;
-
-	down_write(&current->mm->mmap_sem);
-
-	ret = __qib_get_user_pages(start_page, num_pages, p, NULL);
-
-	up_write(&current->mm->mmap_sem);
-
-	return ret;
-}
-
 void qib_release_user_pages(struct page **p, size_t num_pages)
 {
 	if (current->mm) /* during close after signal, mm can be NULL */
-- 
1.8.1.4

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