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    SubjectRe: [PATCH v7 0/5] printk: Userspace format indexing support
    On Thu 2021-06-17 12:10:43, Petr Mladek wrote:
    > On Tue 2021-06-15 17:52:20, Chris Down wrote:
    > > We have a number of systems industry-wide that have a subset of their
    > > functionality that works as follows:
    > >
    > > 1. Receive a message from local kmsg, serial console, or netconsole;
    > > 2. Apply a set of rules to classify the message;
    > > 3. Do something based on this classification (like scheduling a
    > > remediation for the machine), rinse, and repeat.
    > >
    > > This provides a solution to the issue of silently changed or deleted
    > > printks: we record pointers to all printk format strings known at
    > > compile time into a new .printk_index section, both in vmlinux and
    > > modules. At runtime, this can then be iterated by looking at
    > > <debugfs>/printk/index/<module>, which emits the following format, both
    > > readable by humans and able to be parsed by machines:
    > >
    > > $ head -1 vmlinux; shuf -n 5 vmlinux
    > > # <level[,flags]> filename:line function "format"
    > > <5> block/blk-settings.c:661 disk_stack_limits "%s: Warning: Device %s is misaligned\n"
    > > <4> kernel/trace/trace.c:8296 trace_create_file "Could not create tracefs '%s' entry\n"
    > > <6> arch/x86/kernel/hpet.c:144 _hpet_print_config "hpet: %s(%d):\n"
    > > <6> init/do_mounts.c:605 prepare_namespace "Waiting for root device %s...\n"
    > > <6> drivers/acpi/osl.c:1410 acpi_no_auto_serialize_setup "ACPI: auto-serialization disabled\n"
    > >
    > > This mitigates the majority of cases where we have a highly-specific
    > > printk which we want to match on, as we can now enumerate and check
    > > whether the format changed or the printk callsite disappeared entirely
    > > in userspace. This allows us to catch changes to printks we monitor
    > > earlier and decide what to do about it before it becomes problematic.
    > >
    > > There is no additional runtime cost for printk callers or printk itself,
    > > and the assembly generated is exactly the same.
    > >
    > > Chris Down (5):
    > > string_helpers: Escape double quotes in escape_special
    > > printk: Straighten out log_flags into printk_info_flags
    > > printk: Rework parse_prefix into printk_parse_prefix
    > > printk: Userspace format indexing support
    > > printk: index: Add indexing support to dev_printk
    >
    > The patchset looks ready for linux-next from my POV. I could fixup the
    > messages as suggested by Andy when pushing.
    >
    > Well, I would still like to get acks from:
    >
    > + Andy for the 1st patch
    > + Jessica for the changes in the module loader code in 4th patch.

    They provided the Acks, so that we could push it.

    Andrew, this patchset depends on seq_file and string_helpers changes
    that are in -mm tree:

    lib-string_helpers-switch-to-use-bit-macro.patch
    lib-string_helpers-move-escape_np-check-inside-else-branch-in-a-loop.patch
    lib-string_helpers-drop-indentation-level-in-string_escape_mem.patch
    lib-string_helpers-introduce-escape_na-for-escaping-non-ascii.patch
    lib-string_helpers-introduce-escape_nap-to-escape-non-ascii-and-non-printable.patch
    lib-string_helpers-allow-to-append-additional-characters-to-be-escaped.patch
    lib-test-string_helpers-print-flags-in-hexadecimal-format.patch
    lib-test-string_helpers-get-rid-of-trailing-comma-in-terminators.patch
    lib-test-string_helpers-add-test-cases-for-new-features.patch
    maintainers-add-myself-as-designated-reviewer-for-generic-string-library.patch
    seq_file-introduce-seq_escape_mem.patch
    seq_file-add-seq_escape_str-as-replica-of-string_escape_str.patch
    seq_file-convert-seq_escape-to-use-seq_escape_str.patch
    nfsd-avoid-non-flexible-api-in-seq_quote_mem.patch
    seq_file-drop-unused-_escape_mem_ascii.patch


    Would you mind to take this patchset via -mm tree as well, please?

    You were not in CC. Should Chris send v8 with all the Acks and
    you in CC?

    Best Regards,
    Petr

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