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    SubjectRe: [PATCH v2 3/4] printk/btrfs: Handle more message headers
    On Wed,  9 Nov 2016 13:41:30 +0100
    Petr Mladek <pmladek@suse.com> wrote:

    > The commit 4bcc595ccd80decb4245096e ("printk: reinstate KERN_CONT for
    > printing continuation lines") allows to define more message headers
    > for a single message. The motivation is that continuous lines might
    > get mixed. Therefore it make sense to define the right log level
    > for every piece of a cont line.
    >
    > The current btrfs_printk() macros do not support continuous lines
    > at the moment. But better be prepared for a custom messages and
    > avoid potential "lvl" buffer overflow.
    >
    > This patch iterates over the entire message header. It is interested
    > only into the message level like the original code.
    >
    > This patch also introduces PRINTK_MAX_SINGLE_HEADER_LEN. Three bytes
    > are enough for the message level header at the moment. But it used to
    > be three, see the commit 04d2c8c83d0e3ac5f ("printk: convert the format
    > for KERN_<LEVEL> to a 2 byte pattern").
    >
    > Also I fixed the default ratelimit level. It looked very strange
    > when it was different from the default log level.
    >
    > Signed-off-by: Petr Mladek <pmladek@suse.com>
    > ---
    > fs/btrfs/super.c | 26 +++++++++++++++-----------
    > include/linux/printk.h | 2 ++
    > 2 files changed, 17 insertions(+), 11 deletions(-)
    >
    > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
    > index 74ed5aae6cea..c083d84eaa32 100644
    > --- a/fs/btrfs/super.c
    > +++ b/fs/btrfs/super.c
    > @@ -202,27 +202,31 @@ void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function
    > void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
    > {
    > struct super_block *sb = fs_info->sb;
    > - char lvl[4];
    > + char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1];
    > struct va_format vaf;
    > va_list args;
    > - const char *type = logtypes[4];
    > + const char *type = NULL;
    > int kern_level;
    > struct ratelimit_state *ratelimit;
    >
    > va_start(args, fmt);
    >
    > - kern_level = printk_get_level(fmt);
    > - if (kern_level) {
    > + while ((kern_level = printk_get_level(fmt)) != 0) {
    > size_t size = printk_skip_level(fmt) - fmt;
    > - memcpy(lvl, fmt, size);
    > - lvl[size] = '\0';
    > +
    > + if (kern_level >= '0' || kern_level <= '7') {

    Shouldn't this be kernel_level >= '0' && kern_level <= '7' ?

    -- Steve

    > + memcpy(lvl, fmt, size);
    > + lvl[size] = '\0';
    > + type = logtypes[kern_level - '0'];
    > + ratelimit = &printk_limits[kern_level - '0'];
    > + }
    > fmt += size;
    > - type = logtypes[kern_level - '0'];
    > - ratelimit = &printk_limits[kern_level - '0'];
    > - } else {
    > + }
    > +
    > + if (!type) {
    > *lvl = '\0';
    > - /* Default to debug output */
    > - ratelimit = &printk_limits[7];
    > + type = logtypes[4];
    > + ratelimit = &printk_limits[4];
    > }
    >

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