Re: [PATCH v2 5/6] printk: insert newline in devkmsg_read()

From: Alex Elder
Date: Fri Jul 18 2014 - 10:02:21 EST


On 07/18/2014 06:45 AM, Petr Mládek wrote:
> On Thu 2014-07-17 09:09:10, Alex Elder wrote:
>> If a log record has LOG_PREFIX set, its predecessor record should be
>> terminated if it was marked LOG_CONT. In devkmsg_read(), this
>> condition was being ignored, which would lead to such records
>> showing up combined when reading /dev/kmsg. Fix this oversight.
>>
>> Reported-by: Petr Mládek <pmladek@xxxxxxx>
>> Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
>> ---
>> kernel/printk/printk.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
>> index e5ee1cb..3174ba9 100644
>> --- a/kernel/printk/printk.c
>> +++ b/kernel/printk/printk.c
>> @@ -575,6 +575,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
>> char cont;
>> size_t len;
>> ssize_t ret;
>> + bool insert_newline;
>>
>> if (!user)
>> return -EBADF;
>> @@ -626,7 +627,10 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
>> else
>> cont = '-';
>>
>> - len = sprintf(user->buf, "%u,%llu,%llu,%c;",
>> + /* Insert a newline if we're terminating the previous record
>> early */
>
> More correct description would be:
>
> /* Insert a newline if the previous line was not terminated properly */

I will change it as you suggest.

>
>> + insert_newline = (user->prev & LOG_CONT) && (msg->flags & LOG_PREFIX);
>> + len = sprintf(user->buf, "%s%u,%llu,%llu,%c;",
>> + insert_newline ? "\n" : "",
>> (msg->facility << 3) | msg->level,
>> user->seq, ts_usec, cont);
>> user->prev = msg->flags;
>
> Please, do similar change also in msg_print_text() that would fix also
> syslog(). Note that syslog is the place where we stopped to disable
> prefix when there was continuous line before.

I will do this, as you will see in v3 which I plan to post in a
few hours. (Note that this touches a spot where I have yet another
minor bug fix that I have not yet posted... Oh well.)

-Alex

> Best Regards.
> Petr
>

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