James, Martin,
I did not get any feedback from Cisco developers,
could you please pick up this patch?
Unfortunately I have no related hardware and cannot verify the patch.
Usually you can observe following related problems:
- read after lseek beyond end of file, described by NeilBrown in
commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface")
"dd if=<AFFECTED_FILE> bs=1000 skip=1" will incorrectly generate whole last line
- read after lseek on into middle of last line will output expected rest of
last line but then repeat whole last line once again.
- If .show() function generates multi-line output following bash script will never finish.
$ q=;while read -r r;do echo "$((++q)) $r";done < AFFECTED_FILE
On 1/24/20 8:56 AM, Vasily Averin wrote:
> if seq_file .next fuction does not change position index,
> read after some lseek can generate unexpected output.
>
> https://bugzilla.kernel.org/show_bug.cgi?id=206283
> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
> ---
> drivers/scsi/snic/snic_debugfs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/scsi/snic/snic_debugfs.c b/drivers/scsi/snic/snic_debugfs.c
> index 2b34936..b20c724 100644
> --- a/drivers/scsi/snic/snic_debugfs.c
> +++ b/drivers/scsi/snic/snic_debugfs.c
> @@ -419,6 +419,7 @@ void snic_stats_debugfs_init(struct snic *snic)
> static void *
> snic_trc_seq_next(struct seq_file *sfp, void *data, loff_t *pos)
> {
> + (*pos)++;
> return NULL;
> }
>
>
