Hello,
This patch set extends a lock-less NMI per-cpu buffers idea to
handle recursive printk() calls. The basic mechanism is pretty much the
same -- at the beginning of a deadlock-prone section we switch to lock-less
printk callback, and return back to a default printk implementation at the
end; the messages are getting flushed to a logbuf buffer from a safer
context.
See patch 0006 for examples of possible deadlock scenarios that are
handled by printk-safe.
v7:
-- don't touch printk_nmi_enter/exit
-- new printk_safe macros naming: printk_safe_enter_irqsave/exit_irqrestore
-- added printk_safe_enter_irq/printk_safe_exit_irq
-- added patch that converts the rest of printk.c to printk-safe
-- fix build error on !NMI configs
-- improved lost_messages reporting
v6:
-- re-based
-- addressed Petr's review (added comments; moved lost accounting to seq buf)
...
[against next-20161224 + "printk: always report dropped messages" patch set]
Sergey Senozhatsky (8):
printk: use vprintk_func in vprintk()
printk: rename nmi.c and exported api
printk: introduce per-cpu safe_print seq buffer
printk: always use deferred printk when flush printk_safe lines
printk: report lost messages in printk safe/nmi contexts
printk: use printk_safe buffers in printk
printk: remove zap_locks() function
printk: convert the rest to printk-safe
include/linux/printk.h | 21 ++-
init/Kconfig | 16 ++-
init/main.c | 2 +-
kernel/kexec_core.c | 2 +-
kernel/panic.c | 4 +-
kernel/printk/Makefile | 2 +-
kernel/printk/internal.h | 79 ++++++-----
kernel/printk/printk.c | 220 +++++++++++++------------------
kernel/printk/{nmi.c => printk_safe.c} | 234 +++++++++++++++++++++++----------
lib/nmi_backtrace.c | 2 +-
10 files changed, 335 insertions(+), 247 deletions(-)
rename kernel/printk/{nmi.c => printk_safe.c} (53%)
--
2.11.0
