diff options
| author | Michael S. Tsirkin | 2018-04-13 15:35:23 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2018-04-13 17:10:27 -0700 |
| commit | d081107867b85cc7454b9d4f5aea47f65bcf06d1 (patch) | |
| tree | 4cd38640b68f5b53262a2a1e354e3c6efc131103 | |
| parent | c61611f70958d86f659bca25c02ae69413747a8d (diff) | |
mm/gup.c: document return value
__get_user_pages_fast handles errors differently from
get_user_pages_fast: the former always returns the number of pages
pinned, the later might return a negative error code.
Link: http://lkml.kernel.org/r/1522962072-182137-6-git-send-email-mst@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | arch/mips/mm/gup.c | 2 | ||||
| -rw-r--r-- | arch/s390/mm/gup.c | 2 | ||||
| -rw-r--r-- | arch/sh/mm/gup.c | 2 | ||||
| -rw-r--r-- | arch/sparc/mm/gup.c | 4 | ||||
| -rw-r--r-- | mm/gup.c | 4 | ||||
| -rw-r--r-- | mm/util.c | 6 |
6 files changed, 17 insertions, 3 deletions
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c index 1e4658eee13f..5a4875cac1ec 100644 --- a/arch/mips/mm/gup.c +++ b/arch/mips/mm/gup.c @@ -178,6 +178,8 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, /* * Like get_user_pages_fast() except its IRQ-safe in that it won't fall * back to the regular GUP. + * Note a difference with get_user_pages_fast: this always returns the + * number of pages pinned, 0 if no pages were pinned. */ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index 05c8abd864f1..2809d11c7a28 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -220,6 +220,8 @@ static inline int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, /* * Like get_user_pages_fast() except its IRQ-safe in that it won't fall * back to the regular GUP. + * Note a difference with get_user_pages_fast: this always returns the + * number of pages pinned, 0 if no pages were pinned. */ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c index 8045b5bb7075..56c86ca98ecf 100644 --- a/arch/sh/mm/gup.c +++ b/arch/sh/mm/gup.c @@ -160,6 +160,8 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, /* * Like get_user_pages_fast() except its IRQ-safe in that it won't fall * back to the regular GUP. + * Note a difference with get_user_pages_fast: this always returns the + * number of pages pinned, 0 if no pages were pinned. */ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c index 357b6047653a..aee6dba83d0e 100644 --- a/arch/sparc/mm/gup.c +++ b/arch/sparc/mm/gup.c @@ -193,6 +193,10 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, return 1; } +/* + * Note a difference with get_user_pages_fast: this always returns the + * number of pages pinned, 0 if no pages were pinned. + */ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { @@ -1740,7 +1740,9 @@ bool gup_fast_permitted(unsigned long start, int nr_pages, int write) /* * Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to - * the regular GUP. It will only return non-negative values. + * the regular GUP. + * Note a difference with get_user_pages_fast: this always returns the + * number of pages pinned, 0 if no pages were pinned. */ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) diff --git a/mm/util.c b/mm/util.c index 1fc4fa7576f7..45fc3169e7b0 100644 --- a/mm/util.c +++ b/mm/util.c @@ -297,8 +297,10 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) /* * Like get_user_pages_fast() except its IRQ-safe in that it won't fall * back to the regular GUP. - * If the architecture not support this function, simply return with no - * page pinned + * Note a difference with get_user_pages_fast: this always returns the + * number of pages pinned, 0 if no pages were pinned. + * If the architecture does not support this function, simply return with no + * pages pinned. */ int __weak __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) |