diff options
| -rw-r--r-- | include/linux/bitmap.h | 6 | ||||
| -rw-r--r-- | include/linux/cpumask.h | 38 | ||||
| -rw-r--r-- | lib/bitmap.c | 103 |
3 files changed, 147 insertions, 0 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index a36cfcec4e77..37f36dad18bd 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -227,6 +227,12 @@ unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, un int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp, int nmaskbits); +extern int bitmap_print_bitmask_to_buf(char *buf, const unsigned long *maskp, + int nmaskbits, loff_t off, size_t count); + +extern int bitmap_print_list_to_buf(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 f3689a52bfd0..5d4d07a9e1ed 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -983,6 +983,44 @@ cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask) nr_cpu_ids); } +/** + * cpumap_print_bitmask_to_buf - copies the cpumask into the buffer as + * hex values of cpumask + * + * @buf: the buffer to copy into + * @mask: the cpumask to copy + * @off: in the string from which we are copying, we copy to @buf + * @count: the maximum number of bytes to print + * + * The function prints the cpumask into the buffer as hex values of + * cpumask; Typically used by bin_attribute to export cpumask bitmask + * ABI. + * + * Returns the length of how many bytes have been copied. + */ +static inline ssize_t +cpumap_print_bitmask_to_buf(char *buf, const struct cpumask *mask, + loff_t off, size_t count) +{ + return bitmap_print_bitmask_to_buf(buf, cpumask_bits(mask), + nr_cpu_ids, off, count); +} + +/** + * cpumap_print_list_to_buf - copies the cpumask into the buffer as + * comma-separated list of cpus + * + * Everything is same with the above cpumap_print_bitmask_to_buf() + * except the print format. + */ +static inline ssize_t +cpumap_print_list_to_buf(char *buf, const struct cpumask *mask, + loff_t off, size_t count) +{ + return bitmap_print_list_to_buf(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 9401d39e4722..73746d96af81 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -487,6 +487,109 @@ int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp, } EXPORT_SYMBOL(bitmap_print_to_pagebuf); +/** + * bitmap_print_to_buf - convert bitmap to list or hex format ASCII string + * @list: indicates whether the bitmap must be list + * true: print in decimal list format + * false: print in hexadecimal bitmask format + */ +static 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; + + 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; +} + +/** + * bitmap_print_bitmask_to_buf - convert bitmap to hex bitmask format ASCII string + * + * The bitmap_print_to_pagebuf() is used indirectly via its cpumap wrapper + * cpumap_print_to_pagebuf() or directly by drivers to export hexadecimal + * bitmask and decimal list to userspace by sysfs ABI. + * Drivers might be using a normal attribute for this kind of ABIs. A + * normal attribute typically has show entry as below: + * static ssize_t example_attribute_show(struct device *dev, + * struct device_attribute *attr, char *buf) + * { + * ... + * return bitmap_print_to_pagebuf(true, buf, &mask, nr_trig_max); + * } + * show entry of attribute has no offset and count parameters and this + * means the file is limited to one page only. + * bitmap_print_to_pagebuf() API works terribly well for this kind of + * normal attribute with buf parameter and without offset, count: + * bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp, + * int nmaskbits) + * { + * } + * The problem is once we have a large bitmap, we have a chance to get a + * bitmask or list more than one page. Especially for list, it could be + * as complex as 0,3,5,7,9,... We have no simple way to know it exact size. + * It turns out bin_attribute is a way to break this limit. bin_attribute + * has show entry as below: + * static ssize_t + * example_bin_attribute_show(struct file *filp, struct kobject *kobj, + * struct bin_attribute *attr, char *buf, + * loff_t offset, size_t count) + * { + * ... + * } + * With the new offset and count parameters, this makes sysfs ABI be able + * to support file size more than one page. For example, offset could be + * >= 4096. + * bitmap_print_bitmask_to_buf(), bitmap_print_list_to_buf() wit their + * cpumap wrapper cpumap_print_bitmask_to_buf(), cpumap_print_list_to_buf() + * make those drivers be able to support large bitmask and list after they + * move to use bin_attribute. In result, we have to pass the corresponding + * parameters such as off, count from bin_attribute show entry to this API. + * + * @buf: buffer into which string is placed + * @maskp: pointer to bitmap to convert + * @nmaskbits: size of bitmap, in bits + * @off: in the string from which we are copying, We copy to @buf + * @count: the maximum number of bytes to print + * + * The role of cpumap_print_bitmask_to_buf() and cpumap_print_list_to_buf() + * is similar with cpumap_print_to_pagebuf(), the difference is that + * bitmap_print_to_pagebuf() mainly serves sysfs attribute with the assumption + * the destination buffer is exactly one page and won't be more than one page. + * cpumap_print_bitmask_to_buf() and cpumap_print_list_to_buf(), on the other + * hand, mainly serves bin_attribute which doesn't work with exact one page, + * and it can break the size limit of converted decimal list and hexadecimal + * bitmask. + * + * Returns the number of characters actually printed to @buf + */ +int bitmap_print_bitmask_to_buf(char *buf, const unsigned long *maskp, + int nmaskbits, loff_t off, size_t count) +{ + return bitmap_print_to_buf(false, buf, maskp, nmaskbits, off, count); +} +EXPORT_SYMBOL(bitmap_print_bitmask_to_buf); + +/** + * bitmap_print_list_to_buf - convert bitmap to decimal list format ASCII string + * + * Everything is same with the above bitmap_print_bitmask_to_buf() except + * the print format. + */ +int bitmap_print_list_to_buf(char *buf, const unsigned long *maskp, + int nmaskbits, loff_t off, size_t count) +{ + return bitmap_print_to_buf(true, buf, maskp, nmaskbits, off, count); +} +EXPORT_SYMBOL(bitmap_print_list_to_buf); + /* * Region 9-38:4/10 describes the following bitmap structure: * 0 9 12 18 38 N |