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From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Ira Weiny <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Will Deacon <will@kernel.org>,
        Peter Collingbourne <pcc@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        linux-doc@vger.kernel.org, outreachy@lists.linux.dev
Cc:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Mike Rapoport <rppt@linux.ibm.com>
Subject: [PATCH 1/4] mm/highmem: Fix kernel-doc warnings in highmem*.h
Date:   Thu, 21 Apr 2022 20:01:57 +0200
Message-Id: <20220421180200.16901-2-fmdefrancesco@gmail.com>
In-Reply-To: <20220421180200.16901-1-fmdefrancesco@gmail.com>
References: <20220421180200.16901-1-fmdefrancesco@gmail.com>
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`scripts/kernel-doc -v -none include/linux/highmem*` reports the following
warnings:

include/linux/highmem.h:160: warning: expecting prototype for kunmap_atomic(). Prototype was for nr_free_highpages() instead
include/linux/highmem.h:204: warning: No description found for return value of 'alloc_zeroed_user_highpage_movable'
include/linux/highmem-internal.h:256: warning: Function parameter or member '__addr' not described in 'kunmap_atomic'
include/linux/highmem-internal.h:256: warning: Excess function parameter 'addr' description in 'kunmap_atomic'

Fix these warnings by (1) moving the kernel-doc comments from highmem.h to
highmem-internal.h (which is the file were the kunmap_atomic() macro is
actually defined), (2) extending and merging it with the comment which was
already in highmem-internal.h, and (3) using correct parameter names.

Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 include/linux/highmem-internal.h | 14 +++++++++++---
 include/linux/highmem.h          | 15 +++------------
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
index a77be5630209..b099a08e29d3 100644
--- a/include/linux/highmem-internal.h
+++ b/include/linux/highmem-internal.h
@@ -236,9 +236,17 @@ static inline unsigned long totalhigh_pages(void) { return 0UL; }
 
 #endif /* CONFIG_HIGHMEM */
 
-/*
- * Prevent people trying to call kunmap_atomic() as if it were kunmap()
- * kunmap_atomic() should get the return value of kmap_atomic, not the page.
+/**
+ * kunmap_atomic - Unmap the virtual address mapped by kmap_atomic()
+ * @__addr:       Virtual address to be unmapped
+ *
+ * Unmap an address previously mapped by kmap_atomic() and re-enables
+ * pagefaults and preemption. Mappings should be unmapped in the reverse
+ * order that they were mapped. See kmap_local_page() for details.
+ * @__addr can be any address within the mapped page, so there is no need
+ * to subtract any offset that has been added. In contrast to kunmap(),
+ * this function takes the address returned from kmap_atomic(), not the
+ * page passed to it. The compiler will warn you if you pass the page.
  */
 #define kunmap_atomic(__addr)					\
 do {								\
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 39bb9b47fa9c..c3d562b5f0c1 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -37,7 +37,7 @@ static inline void *kmap(struct page *page);
 
 /**
  * kunmap - Unmap the virtual address mapped by kmap()
- * @addr:	Virtual address to be unmapped
+ * @page:	Virtual address to be unmapped
  *
  * Counterpart to kmap(). A NOOP for CONFIG_HIGHMEM=n and for mappings of
  * pages in the low memory area.
@@ -145,17 +145,6 @@ static inline void *kmap_local_folio(struct folio *folio, size_t offset);
  */
 static inline void *kmap_atomic(struct page *page);
 
-/**
- * kunmap_atomic - Unmap the virtual address mapped by kmap_atomic()
- * @addr:	Virtual address to be unmapped
- *
- * Counterpart to kmap_atomic().
- *
- * Effectively a wrapper around kunmap_local() which additionally undoes
- * the side effects of kmap_atomic(), i.e. reenabling pagefaults and
- * preemption.
- */
-
 /* Highmem related interfaces for management code */
 static inline unsigned int nr_free_highpages(void);
 static inline unsigned long totalhigh_pages(void);
@@ -191,6 +180,8 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
  * @vma: The VMA the page is to be allocated for
  * @vaddr: The virtual address the page will be inserted into
  *
+ * Returns: The allocated and zeroed HIGHMEM page
+ *
  * This function will allocate a page for a VMA that the caller knows will
  * be able to migrate in the future using move_pages() or reclaimed
  *
-- 
2.34.1