linux-kernel - [PATCH] mm/gup: fixup for ce35133be382 mm/gup: track FOLL

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Date:   Fri, 6 Mar 2020 18:11:57 -0800
From:   John Hubbard <jhubbard@...dia.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     Matthew Wilcox <willy@...radead.org>, <linux-doc@...r.kernel.org>,
        <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        John Hubbard <jhubbard@...dia.com>
Subject: [PATCH] mm/gup: fixup for ce35133be382 mm/gup: track FOLL_PIN pages

This is a fixup for the mmotm commit ce35133be382
("mm/gup: track FOLL_PIN pages").

Add kerneldoc comments for pin_user_pages*() routines, in order
to get rid of "make -W1" warnings when building mm/gup.o.

This just adds @param documentation of:
    pin_user_pages()
    pin_user_pages_fast()
    pin_user_pages_remote()

The param documentation was stolen from other gup.c functions,
because it looks reasonable enough.

Reported-by: Matthew Wilcox <willy@...radead.org>
Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
 mm/gup.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index f589299b0d4a..54af3b290cb0 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2766,6 +2766,12 @@ EXPORT_SYMBOL_GPL(get_user_pages_fast);
 /**
  * pin_user_pages_fast() - pin user pages in memory without taking locks
  *
+ * @start:      starting user address
+ * @nr_pages:   number of pages from start to pin
+ * @gup_flags:  flags modifying pin behaviour
+ * @pages:      array that receives pointers to the pages pinned.
+ *              Should be at least nr_pages long.
+ *
  * Nearly the same as get_user_pages_fast(), except that FOLL_PIN is set. See
  * get_user_pages_fast() for documentation on the function arguments, because
  * the arguments here are identical.
@@ -2791,6 +2797,21 @@ EXPORT_SYMBOL_GPL(pin_user_pages_fast);
 /**
  * pin_user_pages_remote() - pin pages of a remote process (task != current)
  *
+ * @tsk:	the task_struct to use for page fault accounting, or
+ *		NULL if faults are not to be recorded.
+ * @mm:		mm_struct of target mm
+ * @start:	starting user address
+ * @nr_pages:	number of pages from start to pin
+ * @gup_flags:	flags modifying lookup behaviour
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_pages long. Or NULL, if caller
+ *		only intends to ensure the pages are faulted in.
+ * @vmas:	array of pointers to vmas corresponding to each page.
+ *		Or NULL if the caller does not require them.
+ * @locked:	pointer to lock flag indicating whether lock is held and
+ *		subsequently whether VM_FAULT_RETRY functionality can be
+ *		utilised. Lock must initially be held.
+ *
  * Nearly the same as get_user_pages_remote(), except that FOLL_PIN is set. See
  * get_user_pages_remote() for documentation on the function arguments, because
  * the arguments here are identical.
@@ -2819,6 +2840,15 @@ EXPORT_SYMBOL(pin_user_pages_remote);
 /**
  * pin_user_pages() - pin user pages in memory for use by other devices
  *
+ * @start:	starting user address
+ * @nr_pages:	number of pages from start to pin
+ * @gup_flags:	flags modifying lookup behaviour
+ * @pages:	array that receives pointers to the pages pinned.
+ *		Should be at least nr_pages long. Or NULL, if caller
+ *		only intends to ensure the pages are faulted in.
+ * @vmas:	array of pointers to vmas corresponding to each page.
+ *		Or NULL if the caller does not require them.
+ *
  * Nearly the same as get_user_pages(), except that FOLL_TOUCH is not set, and
  * FOLL_PIN is set.
  *
-- 
2.25.1