Hello, Heiko.
On Fri, Nov 01, 2013 at 03:13:48PM +0100, Heiko Carstens wrote:
> 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.
LOL, that's creative. I guess we'll have to give up using
seq_lseek(). Can you please test the following?
Thanks.
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 382db3c..79b5da2 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -800,7 +800,7 @@ EXPORT_SYMBOL_GPL(sysfs_notify);
const struct file_operations sysfs_file_operations = {
.read = seq_read,
.write = sysfs_write_file,
- .llseek = seq_lseek,
+ .llseek = generic_file_llseek,
.open = sysfs_open_file,
.release = sysfs_release,
.poll = sysfs_poll,
--
tejun
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