I only got your cover letter, but not the patch itself. Can you resend?
On 24.01.20 06:48, Vasily Averin wrote:
> In Aug 2018 NeilBrown noticed
> commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface")
> "Some ->next functions do not increment *pos when they return NULL...
> Note that such ->next functions are buggy and should be fixed.
> A simple demonstration is
>
> dd if=/proc/swaps bs=1000 skip=1
>
> Choose any block size larger than the size of /proc/swaps. This will
> always show the whole last line of /proc/swaps"
>
> Described problem is still actual. If you make lseek into middle of last output line
> following read will output end of last line and whole last line once again.
>
> $ dd if=/proc/swaps bs=1 # usual output
> Filename Type Size Used Priority
> /dev/dm-0 partition 4194812 97536 -2
> 104+0 records in
> 104+0 records out
> 104 bytes copied
>
> $ dd if=/proc/swaps bs=40 skip=1 # last line was generated twice
> dd: /proc/swaps: cannot skip to specified offset
> v/dm-0 partition 4194812 97536 -2
> /dev/dm-0 partition 4194812 97536 -2
> 3+1 records in
> 3+1 records out
> 131 bytes copied
>
> There are lot of other affected files, I've found 30+ including
> /proc/net/ip_tables_matches and /proc/sysvipc/*
>
> Following patch fixes s390-related file
>
> https://bugzilla.kernel.org/show_bug.cgi?id=206283
>
> Vasily Averin (1):
> cio_ignore_proc_seq_next should increase position index
>
> drivers/s390/cio/blacklist.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
