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    Subject[PATCH printk-rework 12/14] printk: kmsg_dump: remove _nolock() variants
    Date
    kmsg_dump_rewind() and kmsg_dump_get_line() are lockless, so there is
    no need for _nolock() variants. Remove these functions and switch all
    callers of the _nolock() variants.

    The functions without _nolock() were chosen because they are already
    exported to kernel modules.

    Signed-off-by: John Ogness <john.ogness@linutronix.de>
    ---
    arch/powerpc/xmon/xmon.c | 4 +--
    include/linux/kmsg_dump.h | 18 +----------
    kernel/debug/kdb/kdb_main.c | 8 ++---
    kernel/printk/printk.c | 60 +++++--------------------------------
    4 files changed, 15 insertions(+), 75 deletions(-)

    diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
    index 43162b885259..4cac114ba32d 100644
    --- a/arch/powerpc/xmon/xmon.c
    +++ b/arch/powerpc/xmon/xmon.c
    @@ -3015,9 +3015,9 @@ dump_log_buf(void)
    catch_memory_errors = 1;
    sync();

    - kmsg_dump_rewind_nolock(&iter);
    + kmsg_dump_rewind(&iter);
    xmon_start_pagination();
    - while (kmsg_dump_get_line_nolock(&iter, false, buf, sizeof(buf), &len)) {
    + while (kmsg_dump_get_line(&iter, false, buf, sizeof(buf), &len)) {
    buf[len] = '\0';
    printf("%s", buf);
    }
    diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
    index 2fdb10ab1799..86673930c8ea 100644
    --- a/include/linux/kmsg_dump.h
    +++ b/include/linux/kmsg_dump.h
    @@ -60,18 +60,13 @@ struct kmsg_dumper {
    #ifdef CONFIG_PRINTK
    void kmsg_dump(enum kmsg_dump_reason reason);

    -bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter, bool syslog,
    - char *line, size_t size, size_t *len);
    -
    bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog,
    char *line, size_t size, size_t *len);

    bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool syslog,
    char *buf, size_t size, size_t *len_out);

    -void kmsg_dump_rewind_nolock(struct kmsg_dumper_iter *iter);
    -
    -void kmsg_dump_rewind(struct kmsg_dumper_iter *dumper_iter);
    +void kmsg_dump_rewind(struct kmsg_dumper_iter *iter);

    int kmsg_dump_register(struct kmsg_dumper *dumper);

    @@ -83,13 +78,6 @@ static inline void kmsg_dump(enum kmsg_dump_reason reason)
    {
    }

    -static inline bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter,
    - bool syslog, const char *line,
    - size_t size, size_t *len)
    -{
    - return false;
    -}
    -
    static inline bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog,
    const char *line, size_t size, size_t *len)
    {
    @@ -102,10 +90,6 @@ static inline bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool sysl
    return false;
    }

    -static inline void kmsg_dump_rewind_nolock(struct kmsg_dumper_iter *iter)
    -{
    -}
    -
    static inline void kmsg_dump_rewind(struct kmsg_dumper_iter *iter)
    {
    }
    diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
    index 7ae9da245e4b..dbf1d126ac5e 100644
    --- a/kernel/debug/kdb/kdb_main.c
    +++ b/kernel/debug/kdb/kdb_main.c
    @@ -2126,8 +2126,8 @@ static int kdb_dmesg(int argc, const char **argv)
    kdb_set(2, setargs);
    }

    - kmsg_dump_rewind_nolock(&iter);
    - while (kmsg_dump_get_line_nolock(&iter, 1, NULL, 0, NULL))
    + kmsg_dump_rewind(&iter);
    + while (kmsg_dump_get_line(&iter, 1, NULL, 0, NULL))
    n++;

    if (lines < 0) {
    @@ -2159,8 +2159,8 @@ static int kdb_dmesg(int argc, const char **argv)
    if (skip >= n || skip < 0)
    return 0;

    - kmsg_dump_rewind_nolock(&iter);
    - while (kmsg_dump_get_line_nolock(&iter, 1, buf, sizeof(buf), &len)) {
    + kmsg_dump_rewind(&iter);
    + while (kmsg_dump_get_line(&iter, 1, buf, sizeof(buf), &len)) {
    if (skip) {
    skip--;
    continue;
    diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
    index c5ea46ed88c7..744b806d5457 100644
    --- a/kernel/printk/printk.c
    +++ b/kernel/printk/printk.c
    @@ -3378,7 +3378,7 @@ void kmsg_dump(enum kmsg_dump_reason reason)
    }

    /**
    - * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
    + * kmsg_dump_get_line - retrieve one kmsg log line
    * @iter: kmsg dumper iterator
    * @syslog: include the "<4>" prefixes
    * @line: buffer to copy the line to
    @@ -3393,18 +3393,18 @@ void kmsg_dump(enum kmsg_dump_reason reason)
    *
    * A return value of FALSE indicates that there are no more records to
    * read.
    - *
    - * The function is similar to kmsg_dump_get_line(), but grabs no locks.
    */
    -bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter, bool syslog,
    - char *line, size_t size, size_t *len)
    +bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog,
    + char *line, size_t size, size_t *len)
    {
    struct printk_info info;
    unsigned int line_count;
    struct printk_record r;
    + unsigned long flags;
    size_t l = 0;
    bool ret = false;

    + printk_safe_enter_irqsave(flags);
    prb_rec_init_rd(&r, &info, line, size);

    if (!iter->active)
    @@ -3428,40 +3428,11 @@ bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter, bool syslog,
    iter->cur_seq = r.info->seq + 1;
    ret = true;
    out:
    + printk_safe_exit_irqrestore(flags);
    if (len)
    *len = l;
    return ret;
    }
    -
    -/**
    - * kmsg_dump_get_line - retrieve one kmsg log line
    - * @iter: kmsg dumper iterator
    - * @syslog: include the "<4>" prefixes
    - * @line: buffer to copy the line to
    - * @size: maximum size of the buffer
    - * @len: length of line placed into buffer
    - *
    - * Start at the beginning of the kmsg buffer, with the oldest kmsg
    - * record, and copy one record into the provided buffer.
    - *
    - * Consecutive calls will return the next available record moving
    - * towards the end of the buffer with the youngest messages.
    - *
    - * A return value of FALSE indicates that there are no more records to
    - * read.
    - */
    -bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog,
    - char *line, size_t size, size_t *len)
    -{
    - unsigned long flags;
    - bool ret;
    -
    - printk_safe_enter_irqsave(flags);
    - ret = kmsg_dump_get_line_nolock(iter, syslog, line, size, len);
    - printk_safe_exit_irqrestore(flags);
    -
    - return ret;
    -}
    EXPORT_SYMBOL_GPL(kmsg_dump_get_line);

    /**
    @@ -3550,22 +3521,6 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool syslog,
    }
    EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);

    -/**
    - * kmsg_dump_rewind_nolock - reset the iterator (unlocked version)
    - * @iter: kmsg dumper iterator
    - *
    - * Reset the dumper's iterator so that kmsg_dump_get_line() and
    - * kmsg_dump_get_buffer() can be called again and used multiple
    - * times within the same dumper.dump() callback.
    - *
    - * The function is similar to kmsg_dump_rewind(), but grabs no locks.
    - */
    -void kmsg_dump_rewind_nolock(struct kmsg_dumper_iter *iter)
    -{
    - iter->cur_seq = latched_seq_read_nolock(&clear_seq);
    - iter->next_seq = prb_next_seq(prb);
    -}
    -
    /**
    * kmsg_dump_rewind - reset the iterator
    * @iter: kmsg dumper iterator
    @@ -3579,7 +3534,8 @@ void kmsg_dump_rewind(struct kmsg_dumper_iter *iter)
    unsigned long flags;

    printk_safe_enter_irqsave(flags);
    - kmsg_dump_rewind_nolock(iter);
    + iter->cur_seq = latched_seq_read_nolock(&clear_seq);
    + iter->next_seq = prb_next_seq(prb);
    printk_safe_exit_irqrestore(flags);
    }
    EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
    --
    2.20.1
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