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Date: Wed, 24 Feb 2010 13:24:00 +0800
From: Cong Wang <amwang@...hat.com>
To: Octavian Purdila <opurdila@...acom.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
Octavian Purdila wrote:
>
> Here is a new version of this patch which fixes both the comma and invalid
> value issues, please give it a try.
>
Sorry, it is even worse. :(
> [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 "50000-50100" gets EINVAL, it should be success.
Writing "50000,50100" fails too.
Please, at least, do some basic testing.
Also some comments below.
> 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>
Please resend the whole patchset, and update the doc in patch 3/3.
> ---
> 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,
The above line is wrong, it should be a part of previous line.
> 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;
'left' should be size_t.
> + 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,
--
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