Hello,
Here is the next series for the printk-rework to remove
@logbuf_lock. Since this lock protected more than just the
ringbuffer, a new finer-grained @syslog_lock is introduced.
With this series, vprintk_store() is lockless.
A consequence of this locklessness is that a different method
for using temporary sprint space was needed. A DIY memory
buffer pool has been implemented for this. Since printk is
used before per-cpu variables are available, I felt that this
was the simplest approach. Feel free to throw tomatoes at me
if another approach should be taken. (And please suggest that
other approach.)
Also as a consequence of a lockless vprintk_store() is that
there is no longer a need for the NMI safe buffers. They are
also removed. The safe buffers for printk recursion are still
used.
This series falls in line with the printk-rework plan as
presented [0] at Linux Plumbers in Lisbon 2019.
The series is based on the printk-rework branch of the printk
git tree:
f35efc78add6 ("printk: remove dict ring")
John Ogness
[0]
https://linuxplumbersconf.org/event/4/contributions/290/attachments/276/463/lpc2019_jogness_printk.pdf
(slide 23)
John Ogness (5):
printk: get new seq before enabling interrupts
printk: kmsg_dump_rewind_nolock: start from first record
printk: use buffer pool for sprint buffers
printk: remove logbuf_lock, add syslog_lock
printk: remove nmi safe buffers
kernel/printk/internal.h | 4 +-
kernel/printk/printk.c | 320 ++++++++++++++++++++++++------------
kernel/printk/printk_safe.c | 64 +-------
3 files changed, 218 insertions(+), 170 deletions(-)
--
2.20.1
