dm ioctl: use kmalloc if possible

If the parameter buffer is small enough, try to allocate it with kmalloc() rather than vmalloc(). vmalloc is noticeably slower than kmalloc because it has to manipulate page tables. In my tests, on PA-RISC this patch speeds up activation 13 times. On Opteron this patch speeds up activation by 5%. This patch introduces a new function free_params() to free the parameters and this uses new flags that record whether or not vmalloc() was used and whether or not the input buffer must be wiped after use.

Mikulas Patocka committed 13 years ago

Commit 9c5091f1 parent 5023e5c1 file · +32 −13Browse files

Unified · Split

drivers/md/dm-ioctl.c+32−13

@@ -1543,7 +1543,21 @@ static int check_version(unsigned int cmd, struct dm_ioctl __user *user) · 1542 unmodified lines
1543	1543	return r;
1544	1544	}
1545	1545
1546		−static int copy_params(struct dm_ioctl __user user, struct dm_ioctl *param)
	1546	+#define DM_PARAMS_VMALLOC 0x0001 /* Params alloced with vmalloc not kmalloc */
	1547	+#define DM_WIPE_BUFFER 0x0010 /* Wipe input buffer before returning from ioctl */
	1548	+
	1549	+static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
	1550	+{
	1551	+ if (param_flags & DM_WIPE_BUFFER)
	1552	+ memset(param, 0, param_size);
	1553	+
	1554	+ if (param_flags & DM_PARAMS_VMALLOC)
	1555	+ vfree(param);
	1556	+ else
	1557	+ kfree(param);
	1558	+}
	1559	+
	1560	+static int copy_params(struct dm_ioctl __user user, struct dm_ioctl param, int param_flags)
1547	1561	{
1548	1562	struct dm_ioctl tmp, *dmi;
1549	1563	int secure_data;
@@ -1556,10 +1570,21 @@ static int copy_params(struct dm_ioctl __user user, struct dm_ioctl *param) · 6 unmodified lines
1556	1570
1557	1571	secure_data = tmp.flags & DM_SECURE_DATA_FLAG;
1558	1572
	1573	+ *param_flags = secure_data ? DM_WIPE_BUFFER : 0;
	1574	+
1559	1575	/*
1560	1576	* Try to avoid low memory issues when a device is suspended.
	1577	+ * Use kmalloc() rather than vmalloc() when we can.
1561	1578	*/
1562		− dmi = __vmalloc(tmp.data_size, GFP_NOIO \| __GFP_REPEAT \| __GFP_HIGH, PAGE_KERNEL);
	1579	+ dmi = NULL;
	1580	+ if (tmp.data_size <= KMALLOC_MAX_SIZE)
	1581	+ dmi = kmalloc(tmp.data_size, GFP_NOIO \| __GFP_NORETRY \| __GFP_NOMEMALLOC \| __GFP_NOWARN);
	1582	+
	1583	+ if (!dmi) {
	1584	+ dmi = __vmalloc(tmp.data_size, GFP_NOIO \| __GFP_REPEAT \| __GFP_HIGH, PAGE_KERNEL);
	1585	+ *param_flags \|= DM_PARAMS_VMALLOC;
	1586	+ }
	1587	+
1563	1588	if (!dmi) {
1564	1589	if (secure_data && clear_user(user, tmp.data_size))
1565	1590	return -EFAULT;
@@ -1585,9 +1610,8 @@ static int copy_params(struct dm_ioctl __user user, struct dm_ioctl *param) · 19 unmodified lines
1585	1610	return 0;
1586	1611
1587	1612	bad:
1588		− if (secure_data)
1589		− memset(dmi, 0, tmp.data_size);
1590		− vfree(dmi);
	1613	+ free_params(dmi, tmp.data_size, *param_flags);
	1614	+
1591	1615	return -EFAULT;
1592	1616	}
1593	1617
@@ -1624,7 +1648,7 @@ static int validate_params(uint cmd, struct dm_ioctl *param) · 30 unmodified lines
1624	1648	static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
1625	1649	{
1626	1650	int r = 0;
1627		− int wipe_buffer;
	1651	+ int param_flags;
1628	1652	unsigned int cmd;
1629	1653	struct dm_ioctl *uninitialized_var(param);
1630	1654	ioctl_fn fn = NULL;
@@ -1662,14 +1686,12 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user) · 31 unmodified lines
1662	1686	/*
1663	1687	* Copy the parameters into kernel space.
1664	1688	*/
1665		− r = copy_params(user, &param);
	1689	+ r = copy_params(user, &param, &param_flags);
1666	1690
1667	1691	if (r)
1668	1692	return r;
1669	1693
1670	1694	input_param_size = param->data_size;
1671		− wipe_buffer = param->flags & DM_SECURE_DATA_FLAG;
1672		−
1673	1695	r = validate_params(cmd, param);
1674	1696	if (r)
1675	1697	goto out;
@@ -1684,10 +1706,7 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user) · 8 unmodified lines
1684	1706	r = -EFAULT;
1685	1707
1686	1708	out:
1687		− if (wipe_buffer)
1688		− memset(param, 0, input_param_size);
1689		−
1690		− vfree(param);
	1709	+ free_params(param, input_param_size, param_flags);
1691	1710	return r;
1692	1711	}
1693	1712