Messages in this thread Patch in this message | | | From | Octavian Purdila <> | Subject | [net-next PATCH v6 2/3] sysctl: add proc_do_large_bitmap | Date | Sat, 27 Feb 2010 03:25:51 +0200 |
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The new function can be used to read/write large bitmaps via /proc. A comma separated range format is used for compact output and input (e.g. 1,3-4,10-10).
Writing into the file will first reset the bitmap then update it based on the given input.
Signed-off-by: Octavian Purdila <opurdila@ixiacom.com> Cc: WANG Cong <amwang@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> --- include/linux/sysctl.h | 2 + kernel/sysctl.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 142 insertions(+), 0 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index f66014c..7bb5cb6 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -980,6 +980,8 @@ extern int proc_doulongvec_minmax(struct ctl_table *, int, void __user *, size_t *, loff_t *); extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void __user *, size_t *, loff_t *); +extern int proc_do_large_bitmap(struct ctl_table *, int, + void __user *, size_t *, loff_t *); /* * Register a set of sysctl names by calling register_sysctl_table diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 0873846..5d599cd 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2071,6 +2071,23 @@ static bool isanyof(char c, const char *v, unsigned len) return true; } +static int proc_skip_anyof(char __user **buf, size_t *size, + const char *v, unsigned len) +{ + char c; + + while (*size) { + if (get_user(c, *buf)) + return -EFAULT; + if (!isanyof(c, v, len)) + break; + (*size)--; + (*buf)++; + } + + return 0; +} + #define TMPBUFLEN 22 /** * proc_get_ulong - reads an ASCII formated integer from a user buffer @@ -2662,6 +2679,129 @@ static int proc_do_cad_pid(struct ctl_table *table, int write, return 0; } +/** + * proc_do_large_bitmap - read/write from/to a large bitmap + * @table: the sysctl table + * @write: %TRUE if this is a write to the sysctl file + * @buffer: the user buffer + * @lenp: the size of the user buffer + * @ppos: file position + * + * The bitmap is stored at table->data and the bitmap length (in bits) + * in table->maxlen. + * + * We use a range comma separated format (e.g. 1,3-4,10-10) so that + * large bitmaps may be represented in a compact manner. Writing into + * the file will clear the bitmap then update it with the given input. + * + * Returns 0 on success. + */ +int proc_do_large_bitmap(struct ctl_table *table, int write, + void __user *_buffer, size_t *lenp, loff_t *ppos) +{ + int err = 0; + bool first = 1; + size_t left = *lenp; + unsigned long bitmap_len = table->maxlen; + char __user *buffer = (char __user *) _buffer; + unsigned long *bitmap = (unsigned long *) table->data; + char tr_a[] = { '-', ',', '\n', 0 }, tr_b[] = { ',', '\n', 0 }, c; + char tr_end[] = { '\n', 0 }; + + + if (!bitmap_len || !left || (*ppos && !write)) { + *lenp = 0; + return 0; + } + + if (write) { + err = proc_skip_anyof(&buffer, &left, tr_end, sizeof(tr_end)); + while (!err && left) { + unsigned long val_a, val_b; + bool neg; + + err = proc_get_ulong(&buffer, &left, &val_a, &neg, tr_a, + sizeof(tr_a), &c); + if (err) + break; + if (val_a >= bitmap_len || neg) { + err = -EINVAL; + break; + } + + val_b = val_a; + if (left) { + buffer++; + left--; + } + + if (c == '-') { + err = proc_get_ulong(&buffer, &left, &val_b, + &neg, tr_b, sizeof(tr_b), + &c); + if (err) + break; + if (val_b >= bitmap_len || neg || + val_a > val_b) { + err = -EINVAL; + break; + } + if (left) { + buffer++; + left--; + } + } + + if (first) + bitmap_clear(bitmap, 0, bitmap_len); + + while (val_a <= val_b) + set_bit(val_a++, bitmap); + + first = 0; + err = proc_skip_anyof(&buffer, &left, tr_end, + sizeof(tr_end)); + } + } else { + unsigned long bit_a, bit_b = 0; + + while (left) { + bit_a = find_next_bit(bitmap, bitmap_len, bit_b); + if (bit_a >= bitmap_len) + break; + bit_b = find_next_zero_bit(bitmap, bitmap_len, + bit_a + 1) - 1; + + err = proc_put_ulong(&buffer, &left, bit_a, 0, first, + ','); + if (err) + break; + if (bit_a != bit_b) { + err = proc_put_char(&buffer, &left, '-'); + if (err) + break; + err = proc_put_ulong(&buffer, &left, bit_b, 0, + 1, 0); + if (err) + break; + } + + first = 0; bit_b++; + } + if (!err) + err = proc_put_char(&buffer, &left, '\n'); + } + + if (first) { + if (err) + return err; + bitmap_clear(bitmap, 0, bitmap_len); + } + *lenp -= left; + *ppos += *lenp; + return 0; +} + #else /* CONFIG_PROC_FS */ int proc_dostring(struct ctl_table *table, int write, -- 1.5.6.5
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