Messages in this thread | | | Date | Mon, 21 Jul 2014 13:57:06 +0200 | From | Petr Mládek <> | Subject | Re: [PATCH v4 6/7] printk: insert newline for truncated records |
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On Fri 2014-07-18 16:28:04, 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. > > We should similarly insert a newline in msg_print_text() in this > case, to avoid formatted records getting merged. > > Suggested-by: Petr Mládek <pmladek@suse.cz> > Signed-off-by: Alex Elder <elder@linaro.org> > --- > kernel/printk/printk.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index e9f0632..a5ad81c 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 the previous line was not terminated properly */ > + 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; > @@ -999,10 +1003,12 @@ static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, > { > const char *text = log_text(msg); > size_t text_size = msg->text_len; > + size_t len = 0; > + bool insert_newline; > bool prefix = true; > bool newline = true; > - size_t len = 0; > > + insert_newline = (prev & LOG_CONT) && (msg->flags & LOG_PREFIX); > if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)) > prefix = false; > > @@ -1023,9 +1029,13 @@ static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, > > if (buf) { > if (print_prefix(msg, syslog, NULL) + > - text_len + 1 >= size - len) > + text_len + 2 >= size - len)
It counts the '\n' even when it is not used. I think that it is even wrong that it calculates prefix when it is not used.
> break; > > + if (insert_newline) { > + insert_newline = false; > + buf[len++] = '\n'; > + } > if (prefix) > len += print_prefix(msg, syslog, buf + len); > memcpy(buf + len, text, text_len); > @@ -1034,6 +1044,8 @@ static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, > buf[len++] = '\n'; > } else { > /* SYSLOG_ACTION_* buffer size only calculation */ > + if (insert_newline) > + len++;
You forgot "insert_newline = false" here.
> if (prefix) > len += print_prefix(msg, syslog, NULL); > len += text_len;
It is just matter of personal style but I would suggest to do this before the do-while cycle:
/* Force newline if the previous text was not properly finished */ if ((prev & LOG_CONT) && (msg->flags & LOG_PREFIX) && (len < size)) { if (buf) buf[len++] = '\n'; else len++; }
IMHO, it is more clear. The do-while cycle already is complex enough.
BTW: This is relared to the first patch. I would either patch all three locations in one patch or better split it into three patches.
Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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