On 2021-02-24, John Ogness <john.ogn...@linutronix.de> wrote: > The @active flag is useless. It should be removed.
I would like to clarify my statement, because the @active flag _did_ protect the arch/um dumper until now. (Although it didn't actually matter because arch/um does not have SMP or preemption support.) In mainline we have 6 dumpers. They can be classified as follows: 1. Dumpers that provide their own synchronization to protect against parallel or nested dump() calls. - arch/powerpc/kernel/nvram_64.c - fs/pstore/platform.c - arch/um/kernel/kmsg_dump.c (after this series) 2. Dumpers that are safe because they only dump on KMSG_DUMP_PANIC, which (currently) can never happen in parallel or nested. - arch/powerpc/platforms/powernv/opal-kmsg.c - drivers/hv/vmbus_drv.c 3. Dumpers that are unsafe and even @active did not provide the needed synchronization. - drivers/mtd/mtdoops.c In all 6 dumpers, @action does not provide any help. That is why it can be removed. But I am concerned about drivers/mtd/mtdoops.c that does not have any synchronization. Since my series is adding sychronization to arch/um/kernel/kmsg_dump.c, I suppose it should also add it to drivers/mtd/mtdoops.c also. And rather than moving the useless @active from kmsg_dumper to kmsg_dump_iter, I should just drop it. Unless there are any objections, I will make these changes for my v3. John Ogness
