On Thu, Oct 31, 2013 at 01:25:06PM -0400, Tejun Heo wrote:
> Hello, Heiko.
>
> On Thu, Oct 31, 2013 at 12:43:58PM +0100, Heiko Carstens wrote:
> > Hi Tejun,
> >
> > I just tried out linux-next and my network doesn't come up anymore.
> > Userspace fails like this:
> >
> > network[2211]: Bringing up interface eth0: sysfs read broadcast value: Invalid argument
> >
> > I bisected that down to:
> >
> > commit 13c589d5b0ac654d9da7e490a2dd548e6b86b4a5
> > Author: Tejun Heo <tj@xxxxxxxxxx>
> > Date: Tue Oct 1 17:42:02 2013 -0400
> >
> > sysfs: use seq_file when reading regular files
>
> Heh, intereting. The content doesn't change over multiple show
> invocations, so the behavior shouldn't change at all for the attribute
> and seq_file handles seeking and partial reads correctly. No idea
> what could go wrong there. It probably was reading
> /sys/devices/BLAHBLAH/net/NETIF/broadcast file. Can you please locate
> the file and do "ls -l" and "cat" on it? If that looks normal, can
> you please strace the network interface config program / script /
> whatever? BTW, what are you running on the system?
Ok, here we go:
before your patch it was like this:
[pid 2888] open("/sys/class/net/eth0/broadcast", O_RDONLY) = 5
[pid 2888] lseek(5, 0, SEEK_END) = 4096
[pid 2888] lseek(5, 0, SEEK_SET) = 0
[pid 2888] read(5, "ff:ff:ff:ff:ff:ff\n", 4096) = 18
[pid 2888] close(5) = 0
With your patch applied I get this:
[pid 2450] open("/sys/class/net/eth0/broadcast", O_RDONLY) = 5
[pid 2450] lseek(5, 0, SEEK_END) = -1 EINVAL (Invalid argument)
[pid 2450] lseek(5, 0, SEEK_SET) = 0
[pid 2450] read(5, 0x557421e8, 4294967295) = -1 EINVAL (Invalid argument)
[pid 2450] close(5) = 0
So the problem is that lseek with SEEK_END doesn't work.
Afterwards the process tried to use the return value of lseek as number of
bytes to be read, which doesn't work ;)
This is a Fedora 17 like system on s390. It's a bit special since the kernel
is 64 bit and whole user space is 32 bit.
--
To unsubscribe from this list: send the line "unsubscribe linux-next" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
