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3ac37a93fa
Prior to commit 5c2992ee7f ("printk: remove console flushing special
cases for partial buffered lines") we would do console_cont_flush()
for each pr_cont() to print cont fragments, so console_unlock() would
actually print data:
pr_cont();
console_lock();
console_unlock()
console_cont_flush(); // print cont fragment
...
pr_cont();
console_lock();
console_unlock()
console_cont_flush(); // print cont fragment
We don't do console_cont_flush() anymore, so when we do pr_cont()
console_unlock() does nothing (unless we flushed the cont buffer):
pr_cont();
console_lock();
console_unlock(); // noop
...
pr_cont();
console_lock();
console_unlock(); // noop
...
pr_cont();
cont_flush();
console_lock();
console_unlock(); // print data
We also wakeup klogd purposelessly for pr_cont() output - un-flushed
cont buffer is not stored in log_buf; there is nothing to pull.
Thus we can console_lock()/console_unlock()/wake_up_klogd() only when
we know that we log_store()-ed a message and there is something to
print to the consoles/syslog.
Link: http://lkml.kernel.org/r/20181002023836.4487-3-sergey.senozhatsky@gmail.com
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.