| Message ID | 1429225433-11946-4-git-send-email-tj@kernel.org |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu 2015-04-16 19:03:40, Tejun Heo wrote: > When a line is printed by multiple printk invocations, each chunk is > directly sent out to console drivers so that they don't get lost. > When the line is completed and stored in the log buffer, the line is > suppressed from going out to consoles as that'd lead to duplicate > outputs. This is tracked with LOG_NOCONS flag. > > The suppression is currently implemented in console_unlock() which > skips invoking call_console_drivers() for LOG_NOCONS messages. This > patch moves the filtering into call_console_drivers() in preparation > of the planned extended console drivers which will deal with the > duplicate messages themselves. > > While this makes call_console_drivers() iterate over LOG_NOCONS > messages, this is extremely unlikely to matter especially given that > continuation lines aren't that common and also simplifies > console_unlock() a bit. > > Signed-off-by: Tejun Heo <tj@kernel.org> > Cc: Kay Sievers <kay@vrfy.org> > Cc: Petr Mladek <pmladek@suse.cz> > --- > kernel/printk/printk.c | 46 ++++++++++++++++++++++++---------------------- > 1 file changed, 24 insertions(+), 22 deletions(-) > > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index 5ea6709..0175c46 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -1417,7 +1417,8 @@ SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) > * log_buf[start] to log_buf[end - 1]. > * The console_lock must be held. > */ > -static void call_console_drivers(int level, const char *text, size_t len) > +static void call_console_drivers(int level, bool nocons, > + const char *text, size_t len) > { > struct console *con; > > @@ -1438,6 +1439,13 @@ static void call_console_drivers(int level, const char *text, size_t len) > if (!cpu_online(smp_processor_id()) && > !(con->flags & CON_ANYTIME)) > continue; > + /* > + * Skip record we have buffered and already printed > + * directly to the console when we received it. > + */ > + if (nocons) > + continue; > + > con->write(con, text, len); > } > } > @@ -1919,7 +1927,8 @@ static struct cont { > } cont; > static struct printk_log *log_from_idx(u32 idx) { return NULL; } > static u32 log_next(u32 idx) { return 0; } > -static void call_console_drivers(int level, const char *text, size_t len) {} > +static void call_console_drivers(int level, bool nocons, > + const char *text, size_t len) {} > static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, > bool syslog, char *buf, size_t size) { return 0; } > static size_t cont_print_text(char *text, size_t size) { return 0; } > @@ -2190,7 +2199,7 @@ static void console_cont_flush(char *text, size_t size) > len = cont_print_text(text, size); > raw_spin_unlock(&logbuf_lock); > stop_critical_timings(); > - call_console_drivers(cont.level, text, len); > + call_console_drivers(cont.level, false, text, len); > start_critical_timings(); > local_irq_restore(flags); > return; > @@ -2234,6 +2243,7 @@ again: > struct printk_log *msg; > size_t len; > int level; > + bool nocons; > > raw_spin_lock_irqsave(&logbuf_lock, flags); > if (seen_seq != log_next_seq) { > @@ -2252,38 +2262,30 @@ again: > } else { > len = 0; > } > -skip: > + > if (console_seq == log_next_seq) > break; > > msg = log_from_idx(console_idx); > - if (msg->flags & LOG_NOCONS) { > - /* > - * Skip record we have buffered and already printed > - * directly to the console when we received it. > - */ > - console_idx = log_next(console_idx); > - console_seq++; > - /* > - * We will get here again when we register a new > - * CON_PRINTBUFFER console. Clear the flag so we > - * will properly dump everything later. > - */ > - msg->flags &= ~LOG_NOCONS; > - console_prev = msg->flags; > - goto skip; > - } > - > level = msg->level; > + nocons = msg->flags & LOG_NOCONS; > len += msg_print_text(msg, console_prev, false, > text + len, sizeof(text) - len); > console_idx = log_next(console_idx); > console_seq++; > console_prev = msg->flags; > + > + /* > + * The log will be processed again when we register a new > + * CON_PRINTBUFFER console. Clear the flag so we will > + * properly dump everything later. > + */ > + msg->flags &= ~LOG_NOCONS; The previous code cleared LOG_NOCONS before saving flags into console_prev. Well, the change does not have any real effect. And the new order makes more sense. This patch looks fine to me. Reviewed-by: Petr Mladek <pmladek@suse.cz> Best Regards, Petr > raw_spin_unlock(&logbuf_lock); > > stop_critical_timings(); /* don't trace print latency */ > - call_console_drivers(level, text, len); > + call_console_drivers(level, nocons, text, len); > start_critical_timings(); > local_irq_restore(flags); > } > -- > 2.1.0 > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 5ea6709..0175c46 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1417,7 +1417,8 @@ SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) * log_buf[start] to log_buf[end - 1]. * The console_lock must be held. */ -static void call_console_drivers(int level, const char *text, size_t len) +static void call_console_drivers(int level, bool nocons, + const char *text, size_t len) { struct console *con; @@ -1438,6 +1439,13 @@ static void call_console_drivers(int level, const char *text, size_t len) if (!cpu_online(smp_processor_id()) && !(con->flags & CON_ANYTIME)) continue; + /* + * Skip record we have buffered and already printed + * directly to the console when we received it. + */ + if (nocons) + continue; + con->write(con, text, len); } } @@ -1919,7 +1927,8 @@ static struct cont { } cont; static struct printk_log *log_from_idx(u32 idx) { return NULL; } static u32 log_next(u32 idx) { return 0; } -static void call_console_drivers(int level, const char *text, size_t len) {} +static void call_console_drivers(int level, bool nocons, + const char *text, size_t len) {} static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, bool syslog, char *buf, size_t size) { return 0; } static size_t cont_print_text(char *text, size_t size) { return 0; } @@ -2190,7 +2199,7 @@ static void console_cont_flush(char *text, size_t size) len = cont_print_text(text, size); raw_spin_unlock(&logbuf_lock); stop_critical_timings(); - call_console_drivers(cont.level, text, len); + call_console_drivers(cont.level, false, text, len); start_critical_timings(); local_irq_restore(flags); return; @@ -2234,6 +2243,7 @@ again: struct printk_log *msg; size_t len; int level; + bool nocons; raw_spin_lock_irqsave(&logbuf_lock, flags); if (seen_seq != log_next_seq) { @@ -2252,38 +2262,30 @@ again: } else { len = 0; } -skip: + if (console_seq == log_next_seq) break; msg = log_from_idx(console_idx); - if (msg->flags & LOG_NOCONS) { - /* - * Skip record we have buffered and already printed - * directly to the console when we received it. - */ - console_idx = log_next(console_idx); - console_seq++; - /* - * We will get here again when we register a new - * CON_PRINTBUFFER console. Clear the flag so we - * will properly dump everything later. - */ - msg->flags &= ~LOG_NOCONS; - console_prev = msg->flags; - goto skip; - } - level = msg->level; + nocons = msg->flags & LOG_NOCONS; len += msg_print_text(msg, console_prev, false, text + len, sizeof(text) - len); console_idx = log_next(console_idx); console_seq++; console_prev = msg->flags; + + /* + * The log will be processed again when we register a new + * CON_PRINTBUFFER console. Clear the flag so we will + * properly dump everything later. + */ + msg->flags &= ~LOG_NOCONS; + raw_spin_unlock(&logbuf_lock); stop_critical_timings(); /* don't trace print latency */ - call_console_drivers(level, text, len); + call_console_drivers(level, nocons, text, len); start_critical_timings(); local_irq_restore(flags); }
When a line is printed by multiple printk invocations, each chunk is directly sent out to console drivers so that they don't get lost. When the line is completed and stored in the log buffer, the line is suppressed from going out to consoles as that'd lead to duplicate outputs. This is tracked with LOG_NOCONS flag. The suppression is currently implemented in console_unlock() which skips invoking call_console_drivers() for LOG_NOCONS messages. This patch moves the filtering into call_console_drivers() in preparation of the planned extended console drivers which will deal with the duplicate messages themselves. While this makes call_console_drivers() iterate over LOG_NOCONS messages, this is extremely unlikely to matter especially given that continuation lines aren't that common and also simplifies console_unlock() a bit. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay@vrfy.org> Cc: Petr Mladek <pmladek@suse.cz> --- kernel/printk/printk.c | 46 ++++++++++++++++++++++++---------------------- 1 file changed, 24 insertions(+), 22 deletions(-)