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Date: Mon, 22 Feb 2010 18:29:13 +0200 From: Octavian Purdila <opurdila@...acom.com> To: Cong Wang <amwang@...hat.com> Cc: David Miller <davem@...emloft.net>, Linux Kernel Network Developers <netdev@...r.kernel.org>, Linux Kernel Developers <linux-kernel@...r.kernel.org>, "Eric W. Biederman" <ebiederm@...ssion.com> Subject: Re: [net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap On Monday 22 February 2010 04:45:44 you wrote: > Octavian Purdila wrote: > > But I think its worth to keep the whitespaces in beetween, e.g. allow > > > > $ echo '1, 2 ,3 ' > ip_local_reserved_ports. > > Sure. > > >> Also, if I write an invalid value, it does reject this, but the previous > >> value in that file is cleared, shouldn't we keep the previous one? > > > > The only way I see to fix this is to return EINVAL if we detect a write > > with offset. > > Yeah, we shouldn't continue once we find any invalid value. > > > IMO we should do that for the other proc write routines as well, as > > otherwise ther result is confusing, e.g. > > > > write("1 2"); write(" 3"); > > > > will set first value in the vector to 1, than second value to 2 then > > *first* value to 3. > > > > I am all for it, but again, this changes userspace ABI. > > Sorry, is this related with the problem I mentioned above? Both "1 2" > and " 3" are valid values. > Never mind, please disregard my "return EINVAL if we detect a write with offset", it breaks the ABI in a significant way. Here is a new version of this patch which fixes both the comma and invalid value issues, please give it a try. [net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap 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@...acom.com> Cc: WANG Cong <amwang@...hat.com> Cc: Eric W. Biederman <ebiederm@...ssion.com> --- include/linux/sysctl.h | 2 + kernel/sysctl.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 136 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 5259727..d8ea839 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2635,6 +2635,140 @@ 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) +{ + 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; + char tr_a[] = { '-', ',', 0 }, tr_b[] = { ',', 0 }, c; + + + if (!bitmap_len || !left || (*ppos && !write)) { + *lenp = 0; + return 0; + } + + if (write) { + err = proc_skip_wspace(&buffer, &left); + while (!err && left) { + unsigned long val_a, val_b; + bool neg; + + err = proc_get_ulong(&buffer, &left, tr_a, + &val_a, &neg, &c); + if (err) + break; + + if (val_a >= bitmap_len || neg) { + err = -EINVAL; + break; + } + + val_b = val_a; + if (left && c == '-') { + /* skip the - */ + buffer++; left--; + + err = proc_get_ulong(&buffer, &left, tr_b, + &val_b, &neg, &c); + if (err) + break; + + if (val_b >= bitmap_len || neg || + val_a > val_b) { + err = -EINVAL; + break; + } + } + + if (left) { + err = proc_skip_wspace(&buffer, &left); + if (err) + break; + if (left) { + if (get_user(c, buffer)) { + err = -EFAULT; + break; + } + if (c != ',') { + err = -EINVAL; + break; + } + /* skip the , */ + buffer++; left--; + } + } + + if (first) + bitmap_clear(bitmap, 0, bitmap_len); + + while (val_a <= val_b) + set_bit(val_a++, bitmap); + + first = 0; + } + if (!err) + err = proc_skip_wspace(&buffer, &left); + } 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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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