[PATCH printk-rework 00/12] printk: remove logbuf_lock

[John Ogness]

Hello,

This series removes @logbuf_lock, exposing the ringbuffer locklessly
to both readers and writers. And since @logbuf_lock was protecting
much more than just the ringbuffer, this series clarifies and cleans
up the various protections using comments, lockless accessors,
atomic types, and a new finer-grained @syslog_log.

This series takes into account the feedback from [0], which was a
series that was partially merged in 5.11.

The first few patches (1-5) are general cleanups to help simplify
later patches. They probably are important enough to stand alone.

John Ogness

[0] https://lkml.kernel.org/r/20201201205341.3871-1-john.ogness@xxxxxxxxxxxxx

John Ogness (12):
  printk: kmsg_dump: remove unused fields
  printk: refactor kmsg_dump_get_buffer()
  printk: consolidate kmsg_dump_get_buffer/syslog_print_all code
  printk: define CONSOLE_LOG_MAX in printk.h
  printk: use seqcount_latch for clear_seq
  printk: use atomic64_t for devkmsg_user.seq
  printk: add syslog_lock
  printk: introduce a kmsg_dump iterator
  um: synchronize kmsg_dumper
  hv: synchronize kmsg_dumper
  printk: remove logbuf_lock
  printk: kmsg_dump: remove _nolock() variants

 arch/powerpc/kernel/nvram_64.c             |  12 +-
 arch/powerpc/platforms/powernv/opal-kmsg.c |   3 +-
 arch/powerpc/xmon/xmon.c                   |   6 +-
 arch/um/kernel/kmsg_dump.c                 |  13 +-
 drivers/hv/vmbus_drv.c                     |  17 +-
 drivers/mtd/mtdoops.c                      |   5 +-
 fs/pstore/platform.c                       |   5 +-
 include/linux/kmsg_dump.h                  |  52 +--
 include/linux/printk.h                     |   1 +
 kernel/debug/kdb/kdb_main.c                |  10 +-
 kernel/printk/internal.h                   |   4 +-
 kernel/printk/printk.c                     | 427 ++++++++++-----------
 kernel/printk/printk_safe.c                |  29 +-
 13 files changed, 281 insertions(+), 303 deletions(-)

-- 
2.20.1