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Message-Id: <201002081851.19999.opurdila@ixiacom.com>
Date: Mon, 8 Feb 2010 18:51:19 +0200
From: Octavian Purdila <opurdila@...acom.com>
To: Cong Wang <amwang@...hat.com>
Cc: David Miller <davem@...emloft.net>, linux-kernel@...r.kernel.org,
eric.dumazet@...il.com, linux-rdma@...r.kernel.org,
netdev@...r.kernel.org, nhorman@...driver.com,
linux-sctp@...r.kernel.org
Subject: Re: [RFC Patch] net: reserve ports for applications using fixed port numbers
On Monday 08 February 2010 05:21:50 you wrote:
> Octavian Purdila wrote:
> > On Friday 05 February 2010 06:45:38 you wrote:
> >> Again, using bitmap algorithm is not a problem and it's better, the
> >> problem is sysctl interface, how would you plan to interact with users
> >> via sysctl/proc if you use bitmap to handle this? I would like to hear
> >> more details about this.
> >
> > We could use something like positive values for setting and negative for
> > reset (e.g. 3 would set the port in the bitmap and -3 would reset it).
>
> Hmm, then how do you output the info of those ports? Arrays of bitmaps?
>
See the patch bellow (work in progress).
BTW, while working on it I added some helpers, which we can use to rewrite the proc_doint/long stuff. I think it will help with readability and eliminates some code duplication as well. What do you guys think about that?
--- linux_2.6.32/main/src/kernel/sysctl.c
+++ linux_2.6.32/main/src/kernel/sysctl.c
@@ -250,6 +250,11 @@
static int max_wakeup_granularity_ns = NSEC_PER_SEC; /* 1 second */
#endif
+static unsigned long test_bitmap[65535/sizeof(long)];
+static int proc_dobitmap(struct ctl_table *table, int write,
+ void __user *buf, size_t *lenp, loff_t *ppos);
+
+
static struct ctl_table kern_table[] = {
{
.ctl_name = CTL_UNNUMBERED,
@@ -1032,6 +1037,15 @@
.proc_handler = &proc_dointvec,
},
#endif
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "bitmap_test",
+ .data = &test_bitmap,
+ .maxlen = 65535,
+ .mode = 0644,
+ .proc_handler = &proc_dobitmap,
+ },
+
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt
@@ -2902,6 +2916,194 @@
return 0;
}
+static int proc_skip_wspace(char __user **buf, size_t *size)
+{
+ char c;
+
+ while (*size) {
+ if (get_user(c, *buf))
+ return -EFAULT;
+ if (!isspace(c))
+ break;
+ *size--; *buf++;
+ }
+
+ return 0;
+}
+
+static inline int _proc_get_ulong(char __user **buf, size_t *size,
+ unsigned long *val, bool *neg)
+{
+#define TMPBUFLEN 21
+ int len = *size;
+ char *p, tmp[TMPBUFLEN];
+
+ if (len > TMPBUFLEN-1)
+ len = TMPBUFLEN-1;
+
+ if (copy_from_user(tmp, *buf, len))
+ return -EFAULT;
+
+ tmp[len] = 0;
+ p = tmp;
+ if (*p == '-' && *size > 1) {
+ *neg = 1;
+ p++;
+ }
+ if (*p < '0' || *p > '9')
+ return -EINVAL;
+
+ *val = simple_strtoul(p, &p, 0);
+
+ len = p - tmp;
+ if ((len < *size) && *p && !isspace(*p))
+ return -EINVAL;
+
+ *buf += len; *size -= len;
+
+ return 0;
+#undef TMPBUFLEN
+}
+
+static int proc_get_long(char __user **buf, size_t *size, long *val)
+{
+ int err;
+ bool neg;
+ unsigned long uval;
+
+ err = _proc_get_ulong(buf, size, &uval, &neg);
+ if (err)
+ return err;
+
+ if (neg)
+ *val = -uval;
+ else
+ *val = uval;
+
+ return 0;
+}
+
+static int proc_get_ulong(char __user **buf, size_t *size, unsigned long *val)
+{
+ int err;
+ bool neg;
+
+ err = _proc_get_ulong(buf, size, val, &neg);
+ if (err)
+ return err;
+ if (neg)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int proc_put_ulong(char __user **buf, size_t *size, unsigned long val,
+ bool first)
+{
+#define TMPBUFLEN 21
+ int len;
+ char tmp[TMPBUFLEN], *p = tmp;
+
+ if (!first)
+ *p++ = '\t';
+ sprintf(p, "%lu", val);
+ len = strlen(tmp);
+ if (len > *size)
+ len = *size;
+ if (copy_to_user(*buf, tmp, len))
+ return -EFAULT;
+ *size -= len;
+ *buf += len;
+ return 0;
+#undef TMPBUFLEN
+}
+
+static int proc_put_newline(char __user **buf, size_t *size)
+{
+ if (*size) {
+ if (put_user('\n', *buf))
+ return -EFAULT;
+ *size--, *buf++;
+ }
+ return 0;
+}
+
+static int proc_dobitmap(struct ctl_table *table, int write,
+ void __user *buf, 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 *) buf;
+
+ if (!bitmap_len || !left || (*ppos && !write)) {
+ *lenp = 0;
+ return 0;
+ }
+
+ if (write) {
+ while (left) {
+ long val;
+
+ err = proc_skip_wspace(&buffer, &left);
+ if (err)
+ break;
+ if (!left) {
+ err = -EINVAL;
+ break;
+ }
+ err = proc_get_long(&buffer, &left, &val);
+ if (err)
+ break;
+ if (abs(val) > bitmap_len) {
+ err = -EINVAL;
+ break;
+ }
+
+ if (val < 0)
+ 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);
+ printk("%s:%d %lu\n", __func__, __LINE__, bit);
+ if (bit >= bitmap_len)
+ break;
+ err = proc_put_ulong(&buffer, &left, bit, first);
+ printk("%s:%d %d\n", __func__, __LINE__, err);
+ if (err)
+ break;
+ first = 0; bit++;
+ }
+ if (!err)
+ err = proc_put_newline(&buffer, &left);
+ }
+
+ if (first) {
+ if (write && !err)
+ err = -EINVAL;
+ if (err)
+ return err;
+ }
+
+ if (err == -EFAULT)
+ return err;
+
+ printk("%s:%d %d %d\n", __func__, __LINE__, *lenp, left);
+ *lenp -= left;
+ *ppos += *lenp;
+ return 0;
+}
+
#else /* CONFIG_PROC_FS */
int proc_dostring(struct ctl_table *table, int write,
--
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