Hello, Here is a v3 for the first series to rework the printk subsystem. The v2 and history are here [0]. This first series only replaces the existing ringbuffer implementation. No locking is removed. No semantics/behavior of printk are changed. Reviews on the ringbuffer are still ongoing, but I was asked to post this new version since several changes from v2 have been already agreed upon. The series is based on v5.8-rc1. The list of changes since v2: printk.c ======== - console_unlock(): fix extended console printing [1] printk_ringbuffer ================= - data_push_tail(): fixed handling when another CPU already pushed the tail [2] - desc_push_tail(): added a full memory barrier before the descriptor tail push [3] - data_make_reusable()/data_alloc(): changed block ID reading/writing from READ_ONCE()/WRITE_ONCE() to regular assignments [4] - data_make_reusable(): removed unnecessary data tail re-check [5] - general: folded all smp_mb() and smp_wmb() calls into their neighboring cmpxchg_relaxed(), changing them to full cmpxchg() calls [6] - desc_read(): changed descriptor content reading from READ_ONCE() to memcpy() since it served no purpose for the legal data race - general: cleaned up memory barrier comments; in particular made sure that the reader and writer sides of the memory barrier pairs match in their descriptions - added a new section in the memory barrier documentation (near the top of printk_ringbuffer.c) that lists all 10 memory barrier pairs and briefly describes what they are ordering - _prb_read_valid(): changed the helper function to static - general: changed block size argument type from "unsigned long" to "unsigned int" since a record's *_buf_size fields are of type "unsigned int" - general: allow some lines to go beyond 80 characters John Ogness [0] https://lkml.kernel.org/r/20200501094010.17694-1-john.ogness@xxxxxxxxxxxxx [1] https://lkml.kernel.org/r/87ftcd86d2.fsf@xxxxxxxxxxxxxxxxxxxx [2] https://lkml.kernel.org/r/87v9ktcs3q.fsf@xxxxxxxxxxxxxxxxxxxx [3] https://lkml.kernel.org/r/87bllpyzgr.fsf@xxxxxxxxxxxxxxxxxxxx [4] https://lkml.kernel.org/r/87tuzkuxtw.fsf@xxxxxxxxxxxxxxxxxxxx [5] https://lkml.kernel.org/r/87pna5mjtp.fsf@xxxxxxxxxxxxxxxxxxxx John Ogness (3): crash: add VMCOREINFO macro to define offset in a struct declared by typedef printk: add lockless ringbuffer printk: use the lockless ringbuffer include/linux/crash_core.h | 3 + include/linux/kmsg_dump.h | 2 - kernel/printk/Makefile | 1 + kernel/printk/printk.c | 944 ++++++++-------- kernel/printk/printk_ringbuffer.c | 1674 +++++++++++++++++++++++++++++ kernel/printk/printk_ringbuffer.h | 352 ++++++ 6 files changed, 2527 insertions(+), 449 deletions(-) create mode 100644 kernel/printk/printk_ringbuffer.c create mode 100644 kernel/printk/printk_ringbuffer.h -- 2.20.1 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
