lkml.org 
[lkml]   [2020]   [Sep]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Subject[PATCH printk 0/5] printk: remove logbuf_lock
    Date
    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

    \
     
     \ /
      Last update: 2020-09-22 17:38    [W:4.151 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site