Actually, judging from how other drivers do this, the mii_ioctl_data
structure is really supposed to be assigned to &ifr.ifr_data. I dont
believe there is any storage where ifr_data points, and the ifr_ifru union
is 16 bytes, which is the size of the mii_ioctl_data structure.
-J
"Cureington, Tony" <tony.cureington@xxxxxx>@lists.sourceforge.net on
09/17/2002 12:28:52 PM
Sent by: bonding-devel-admin@xxxxxxxxxxxxxxxxxxxxx
To: "Andrew Morton" <akpm@xxxxxxxxx>, "Pascal Brisset"
<pascal.brisset-ml@xxxxxxxxxx>
cc: <bonding-devel@xxxxxxxxxxxxxxxxxxxxx>, <netdev@xxxxxxxxxxx>
Subject: RE: [Bonding-devel] Re: Bonding driver unreliable under high
CPU load
I've been running some similar code (on 2.4.18) that makes the ioctl a
macro - we must handle the MII ioctls too. The patch below also corrects
the mii pointer being assigned the address of a pointer (&ifr.ifr_data,
ifr_data is a macro that produces a pointer) instead of the pointer itself.
The patch:
--- linux-2.4.20-pre7/drivers/net/bonding.c Tue Sep 17 09:54:35 2002
+++ linux-2.4.20-pre7_mod/drivers/net/bonding.c Tue Sep 17 11:18:28 2002
@@ -316,6 +316,28 @@
#define IS_UP(dev) ((((dev)->flags & (IFF_UP)) == (IFF_UP)) && \
(netif_running(dev) && netif_carrier_ok(dev)))
+/* this IOCTL macro is used to prevent network drivers from returning
-EFAULT
+ * from the ioctl, returning -EFAULT causes a link up status to be
returned
+ * from bond_check_dev_link even when the link is even connected. this
macro
+ * allows the get_user/copy_from_user in network drivers ioctls to work
without
+ * intermittently returning -EFAULT. this turns off argument validity
+ * checking on the address passed to the network driver ioctl.
+ *
+ * this method of turning off argument validity checking is also used in
the
+ * following drivers:
+ * /usr/src/linux/drivers/addon/iscsi/; addon/cpip; net/hamradio;
+ * net/wan; sound/;
+ *
+ * ioctl must be set to dev->do_ioctl before this macro
+ */
+#define IOCTL(dev, arg, cmd) ({ \
+ int ret; \
+ mm_segment_t fs = get_fs(); \
+ set_fs(get_ds()); \
+ ret = ioctl(dev, arg, cmd); \
+ set_fs(fs); \
+ ret; })
+
static void bond_restore_slave_flags(slave_t *slave)
{
slave->dev->flags = slave->original_flags;
@@ -416,7 +438,7 @@
/* effect... */
etool.cmd = ETHTOOL_GLINK;
ifr.ifr_data = (char*)&etool;
- if (ioctl(dev, &ifr, SIOCETHTOOL) == 0) {
+ if (IOCTL(dev, &ifr, SIOCETHTOOL) == 0) {
if (etool.data == 1) {
return(MII_LINK_READY);
}
@@ -431,13 +453,13 @@
*/
/* Yes, the mii is overlaid on the ifreq.ifr_ifru */
- mii = (struct mii_ioctl_data *)&ifr.ifr_data;
- if (ioctl(dev, &ifr, SIOCGMIIPHY) != 0) {
+ mii = (struct mii_ioctl_data *)ifr.ifr_data;
+ if (IOCTL(dev, &ifr, SIOCGMIIPHY) != 0) {
return MII_LINK_READY; /* can't tell */
}
mii->reg_num = 1;
- if (ioctl(dev, &ifr, SIOCGMIIREG) == 0) {
+ if (IOCTL(dev, &ifr, SIOCGMIIREG) == 0) {
/*
* mii->val_out contains MII reg 1, BMSR
* 0x0004 means link established
> -----Original Message-----
> From: Andrew Morton [mailto:akpm@xxxxxxxxx]
> Sent: Saturday, September 14, 2002 10:24 PM
> To: Pascal Brisset
> Cc: bonding-devel@xxxxxxxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxx
> Subject: [Bonding-devel] Re: Bonding driver unreliable under high CPU
> load
>
>
> Pascal Brisset wrote:
> >
> > I would like to confirm the problem reported by Tony Cureington at
> >
> http://sourceforge.net/mailarchive/forum.php?thread_id=1015008
> &forum_id=2094
> >
> > Problem: In MII-monitoring mode, when the CPU load is high,
> > the ethernet bonding driver silently fails to detect dead links.
> >
> > How to reproduce:
> > i686, 2.4.19; "modprobe bonding mode=1 miimon=100"; ifenslave two
> > interfaces; ping while you plug/unplug cables. Bonding will
> > switch to the available interface, as expected. Now load the CPU
> > with "while(1) { }", and failover will not work at all anymore.
> >
> > Explanation:
> > The bonding driver monitors the state of its slave interfaces by
> > calling their dev->do_ioctl(SIOCGMIIREG|ETHTOOL_GLINK) from a
> > timer callback function. Whenever this occurs during a user task,
> > the get_user() in the ioctl handling code of the slave fails with
> > -EFAULT because the ifreq struct is allocated in the stack of the
> > timer function, above 0xC0000000. In that case, the bonding driver
> > considers the link up by default.
> >
> > This problem went unnoticed because for most applications, when the
> > active link dies, the host becomes idle and the monitoring function
> > gets a chance to run during a kernel thread (in which case
> it works).
> > The active-backup switchover is just slower than it should be.
> > Serious trouble only happens when the active link dies
> during a long,
> > CPU-intensive job.
> >
> > Is anyone working on a fix ? Maybe running the monitoring stuff in
> > a dedicated task ?
>
> Running the ioctl in interrupt context is bad. Probably what should
> happen here is that the whole link monitoring function be pushed up
> to process context via a schedule_task() callout, or a do it in a
> dedicated kernel thread.
>
> This patch will probably make it work, but the slave device's
> ioctl simply
> isn't designed to be called from this context - it could try to take
> a semaphore, or a non-interrupt-safe lock or anything.
>
> --- linux-2.4.20-pre7/drivers/net/bonding.c Thu Sep 12 20:35:22 2002
> +++ linux-akpm/drivers/net/bonding.c Sat Sep 14 20:23:45 2002
> @@ -208,6 +208,7 @@
> #include <asm/io.h>
> #include <asm/dma.h>
> #include <asm/uaccess.h>
> +#include <asm/processor.h>
> #include <linux/errno.h>
>
> #include <linux/netdevice.h>
> @@ -401,6 +402,7 @@ static u16 bond_check_dev_link(struct ne
> struct ifreq ifr;
> struct mii_ioctl_data *mii;
> struct ethtool_value etool;
> + int ioctl_ret;
>
> if ((ioctl = dev->do_ioctl) != NULL) { /* ioctl to
> access MII */
> /* TODO: set pointer to correct ioctl on a per
> team member */
> @@ -416,7 +418,13 @@ static u16 bond_check_dev_link(struct ne
> /* effect...
> */
> etool.cmd = ETHTOOL_GLINK;
> ifr.ifr_data = (char*)&etool;
> - if (ioctl(dev, &ifr, SIOCETHTOOL) == 0) {
> + {
> + mm_segment_t old_fs = get_fs();
> + set_fs(KERNEL_DS);
> + ioctl_ret = ioctl(dev, &ifr, SIOCETHTOOL);
> + set_fs(old_fs);
> + }
> + if (ioctl_ret == 0) {
> if (etool.data == 1) {
> return(MII_LINK_READY);
> }
>
>
> -
>
>
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