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Date: Mon, 12 Apr 2010 06:04:14 -0400
From: Amerigo Wang <amwang@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Octavian Purdila <opurdila@...acom.com>,
Eric Dumazet <eric.dumazet@...il.com>,
penguin-kernel@...ove.SAKURA.ne.jp, netdev@...r.kernel.org,
Neil Horman <nhorman@...driver.com>,
Amerigo Wang <amwang@...hat.com>, ebiederm@...ssion.com,
David Miller <davem@...emloft.net>
Subject: [Patch 2/3] sysctl: add proc_do_large_bitmap
From: Octavian Purdila <opurdila@...acom.com>
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>
Signed-off-by: WANG Cong <amwang@...hat.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
---
Index: linux-2.6/include/linux/sysctl.h
===================================================================
--- linux-2.6.orig/include/linux/sysctl.h
+++ linux-2.6/include/linux/sysctl.h
@@ -980,6 +980,8 @@ extern int proc_doulongvec_minmax(struct
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
Index: linux-2.6/kernel/sysctl.c
===================================================================
--- linux-2.6.orig/kernel/sysctl.c
+++ linux-2.6/kernel/sysctl.c
@@ -2072,6 +2072,23 @@ static bool isanyof(char c, const char *
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_long - reads an ASCII formated integer from a user buffer
@@ -2663,6 +2680,135 @@ static int proc_do_cad_pid(struct ctl_ta
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;
+ unsigned long *tmp_bitmap = NULL;
+ 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) {
+ tmp_bitmap = kzalloc(BITS_TO_LONGS(bitmap_len) * sizeof(unsigned long),
+ GFP_KERNEL);
+ if (!tmp_bitmap)
+ return -ENOMEM;
+ 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_long(&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_long(&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--;
+ }
+ }
+
+ while (val_a <= val_b)
+ set_bit(val_a++, tmp_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_long(&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_long(&buffer, &left, bit_b, 0,
+ 1, 0);
+ if (err)
+ break;
+ }
+
+ first = 0; bit_b++;
+ }
+ if (!err)
+ err = proc_put_char(&buffer, &left, '\n');
+ }
+
+ if (!err) {
+ if (write)
+ memcpy(bitmap, tmp_bitmap,
+ BITS_TO_LONGS(bitmap_len) * sizeof(unsigned long));
+ kfree(tmp_bitmap);
+ *lenp -= left;
+ *ppos += *lenp;
+ return 0;
+ } else {
+ kfree(tmp_bitmap);
+ return err;
+ }
+}
+
#else /* CONFIG_PROC_FS */
int proc_dostring(struct ctl_table *table, int write,
--
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