Hello, Here is v4 of a series to remove @logbuf_lock, exposing the ringbuffer locklessly to both readers and writers. v3 is here [0]. 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_lock. Removing @logbuf_lock required changing the semantics of the kmsg_dumper callback in order to work locklessly. This series adjusts all kmsg_dumpers and users of the kmsg_dump_get_*() functions for the new semantics. This series is based on next-20210303. Changes since v3: - disable interrupts in the arch/um kmsg_dumper - reduce CONSOLE_LOG_MAX value from 4096 back to 1024 to revert the increasd 3KiB static memory footprint - change the kmsg_dumper() callback prototype back to how it was because some dumpers need the registered object for container_of() usage - for kmsg_dump_get_line()/kmsg_dump_get_buffer() restrict the minimal allowed sequence number to the cleared sequence number John Ogness [0] https://lore.kernel.org/lkml/20210225202438.28985-1-john.ogness@xxxxxxxxxxxxx/ John Ogness (15): um: synchronize kmsg_dumper mtd: mtdoops: synchronize kmsg_dumper printk: limit second loop of syslog_print_all printk: kmsg_dump: remove unused fields printk: refactor kmsg_dump_get_buffer() printk: consolidate kmsg_dump_get_buffer/syslog_print_all code printk: introduce CONSOLE_LOG_MAX printk: use seqcount_latch for clear_seq printk: use atomic64_t for devkmsg_user.seq printk: add syslog_lock printk: kmsg_dumper: remove @active field printk: introduce a kmsg_dump iterator printk: remove logbuf_lock printk: kmsg_dump: remove _nolock() variants printk: console: remove unnecessary safe buffer usage arch/powerpc/kernel/nvram_64.c | 8 +- arch/powerpc/xmon/xmon.c | 6 +- arch/um/kernel/kmsg_dump.c | 13 +- drivers/hv/vmbus_drv.c | 4 +- drivers/mtd/mtdoops.c | 17 +- fs/pstore/platform.c | 5 +- include/linux/kmsg_dump.h | 47 ++-- kernel/debug/kdb/kdb_main.c | 10 +- kernel/printk/internal.h | 4 +- kernel/printk/printk.c | 464 +++++++++++++++++---------------- kernel/printk/printk_safe.c | 27 +- 11 files changed, 310 insertions(+), 295 deletions(-) -- 2.20.1
