Messages in this thread Patch in this message |  | | From | Octavian Purdila <> | Subject | [net-next PATCH v3 2/3] sysctl: add proc_dobitmap | Date | Thu, 11 Feb 2010 04:09:19 +0200 |
| |
The new function can be used to update bitmaps via /proc. Bits can be set by writing positive values in the file and cleared by writing negative values (e.g. 0 2 will set bits 1 and 3, -0 -2 will clear them). Reading will show only the set bits.
Signed-off-by: Octavian Purdila <opurdila@ixiacom.com> Cc: WANG Cong <amwang@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> --- include/linux/sysctl.h | 2 + kernel/sysctl.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+), 0 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 9f236cd..ba89bf2 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -985,6 +985,8 @@ 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_dobitmap(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 b0f9618..b8959f4 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2596,6 +2596,82 @@ static int proc_do_cad_pid(struct ctl_table *table, int write, return 0; } +/** + * proc_dobitmap - read/write from/to a 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 + * @ppos: the current position in the file + * + * The bitmap is stored at table->data and the bitmap length (in bits) + * in table->maxlen. Reading from the proc file will show the set bits. + * Writing positive values sets the bits, negative values clears them + * (e.g. 0 2 sets the first and 3rd bit, -0 -2 clears them). + * + * Returns 0 on success. + */ +int proc_dobitmap(struct ctl_table *table, int write, + void __user *_buffer, size_t *lenp, loff_t *ppos) +{ + bool first = 1; + unsigned long *bitmap = (unsigned long *) table->data; + unsigned long bitmap_len = table->maxlen; + int left = *lenp, err = 0; + char __user *buffer = (char __user *) _buffer; + + if (!bitmap_len || !left || (*ppos && !write)) { + *lenp = 0; + return 0; + } + + if (write) { + while (left) { + unsigned long val; + bool neg; + + err = proc_get_next_ulong(&buffer, &left, &val, &neg); + if (err) + break; + if (val >= bitmap_len) { + err = -EINVAL; + break; + } + if (neg) + clear_bit(val, bitmap); + else + set_bit(val, bitmap); + first = 0; + } + if (!err) + err = proc_skip_wspace(&buffer, &left); + } else { + unsigned long bit = 0; + + while (left) { + bit = find_next_bit(bitmap, bitmap_len, bit); + if (bit >= bitmap_len) + break; + err = proc_put_ulong(&buffer, &left, bit, 0, first); + if (err) + break; + first = 0; bit++; + } + if (!err) + err = proc_put_newline(&buffer, &left); + } + + if (first && write && !err) + err = -EINVAL; + if (err == -EFAULT /* do we really need to check for -EFAULT? */ || + (write && first)) + return err ? : -EINVAL; + *lenp -= left; + *ppos += *lenp; + return 0; +} + #else /* CONFIG_PROC_FS */ int proc_dostring(struct ctl_table *table, int write, -- 1.5.6.5
|  |