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Subject[PATCH v4 1/4] lib: bitmap: introduce bitmap_print_to_buf
Date
From: Tian Tao <tiantao6@hisilicon.com>

New API bitmap_print_to_buf() with bin_attribute to avoid maskp
exceeding PAGE_SIZE. bitmap_print_to_pagebuf() is a special case
of bitmap_print_to_buf(), so in bitmap_print_to_pagebuf() call
bitmap_print_to_buf().

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stefano Brivio <sbrivio@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: "Ma, Jianpeng" <jianpeng.ma@intel.com>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
---
include/linux/bitmap.h | 2 ++
include/linux/cpumask.h | 21 +++++++++++++++++++++
lib/bitmap.c | 37 +++++++++++++++++++++++++++++++++++--
3 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index a36cfcec4e77..0de6effa2797 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -226,6 +226,8 @@ void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int n
unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
int bitmap_print_to_pagebuf(bool list, char *buf,
const unsigned long *maskp, int nmaskbits);
+int bitmap_print_to_buf(bool list, char *buf, const unsigned long *maskp,
+ int nmaskbits, loff_t off, size_t count);

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index bfc4690de4f4..1bef69e4b950 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -983,6 +983,27 @@ cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask)
nr_cpu_ids);
}

+/**
+ * cpumap_print_to_buf - copies the cpumask into the buffer either
+ * as comma-separated list of cpus or hex values of cpumask
+ * @list: indicates whether the cpumap must be list
+ * @mask: the cpumask to copy
+ * @buf: the buffer to copy into
+ * @off: in the string from which we are copying, We copy to @buf + off
+ * @count: the maximum number of bytes to print
+ *
+ * The role of cpumap_print_to_buf() and cpumap_print_to_pagebuf() is
+ * the same, the difference is that buf of bitmap_print_to_buf()
+ * can be more than one pagesize.
+ */
+static inline ssize_t
+cpumap_print_to_buf(bool list, char *buf, const struct cpumask *mask,
+ loff_t off, size_t count)
+{
+ return bitmap_print_to_buf(list, buf, cpumask_bits(mask),
+ nr_cpu_ids, off, count);
+}
+
#if NR_CPUS <= BITS_PER_LONG
#define CPU_MASK_ALL \
(cpumask_t) { { \
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 74ceb02f45e3..ed7ef6e2edca 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -461,6 +461,40 @@ int bitmap_parse_user(const char __user *ubuf,
}
EXPORT_SYMBOL(bitmap_parse_user);

+/**
+ * bitmap_print_to_buf - convert bitmap to list or hex format ASCII string
+ * @list: indicates whether the bitmap must be list
+ * @buf: the kernel space buffer to read to
+ * @maskp: pointer to bitmap to convert
+ * @nmaskbits: size of bitmap, in bits
+ * @off: offset in data buffer below
+ * @count: the maximum number of bytes to print
+ *
+ * The role of bitmap_print_to_buf() and bitmap_print_to_pagebuf() is
+ * the same, the difference is that buf of bitmap_print_to_buf()
+ * can be more than one pagesize.
+ */
+int bitmap_print_to_buf(bool list, char *buf, const unsigned long *maskp,
+ int nmaskbits, loff_t off, size_t count)
+{
+ const char *fmt = list ? "%*pbl\n" : "%*pb\n";
+ ssize_t size;
+ void *data;
+
+ if (off == LLONG_MAX && count == PAGE_SIZE - offset_in_page(buf))
+ return scnprintf(buf, count, fmt, nmaskbits, maskp);
+
+ data = kasprintf(GFP_KERNEL, fmt, nmaskbits, maskp);
+ if (!data)
+ return -ENOMEM;
+
+ size = memory_read_from_buffer(buf, count, &off, data, strlen(data) + 1);
+ kfree(data);
+
+ return size;
+}
+EXPORT_SYMBOL(bitmap_print_to_buf);
+
/**
* bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
* @list: indicates whether the bitmap must be list
@@ -482,8 +516,7 @@ int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
{
ptrdiff_t len = PAGE_SIZE - offset_in_page(buf);

- return list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
- scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
+ return bitmap_print_to_buf(list, buf, maskp, nmaskbits, LLONG_MAX, len);
}
EXPORT_SYMBOL(bitmap_print_to_pagebuf);

--
2.25.1
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