[PATCH printk v2 0/7] printk: cleanup buffer handling

John Ogness
2022-11-23T23:14:21Z

Hi,

This is v2 of a series to cleanup buffer handling and prepare for
code sharing with the upcoming threaded/atomic consoles. v1 is
patches 13-18 of [0].

Changes since v1:

- Explain why console.h was chosen for buffer size defines.

- Keep DROPPED_TEXT_MAX define in printk.c.

- Put new BIT()-macro usage for console flags into its own commit.

- Modify descriptions for console flags as suggested.

- Add argument names and types to console callback definitions to
satisfy checkpatch.pl complaints.

- Avoid temporary usage of an ext_text/dropped_text union mid-series.

- Rename various structures, fields, and functions:

struct cons_text_buf -> struct console_buffers

struct cons_outbuf_desc -> struct console_message

cons_outbuf_desc.txtbuf -> console_message.cbufs

cons_outbuf_desc.len -> console_message.outbuf_len

cons_outbuf_desc.extmsg -> console_message.is_extmsg

cons_fill_outbuf() -> console_get_next_message()

cons_print_dropped() -> msg_print_dropped()

- Remove cons_outbuf_desc->dropped and make @dropped an argument of
msg_print_dropped() instead.

- Use "ext_text" and "ext_text_size" names for stack variables when
they refer to console_buffers->ext_text.

- Add a compile-time verification that DROPPED_TEXT_MAX is less than
CONSOLE_EXT_LOG_MAX - CONSOLE_LOG_MAX since the code expects that
a dropped+regular message will fit in console_buffers->ext_text.

- Replace hard-coded CONSOLE_LOG_MAX and CONSOLE_EXT_LOG_MAX usage
with sizeof() usage.

- For dropped messages, copy the regular message to append the
dropped message, instead of copying the dropped message to prepend
the regular message. Now it is not a hack and there is no need for
the __no_randomize_layout annotation.

- Reset console->dropped explicitly instead of relying on
msg_print_dropped() side-effects.

- Rework and expand comments and commit messages as requested.

John Ogness

[0] https://lore.kernel.org/lkml/20220924000454.3319186-1-john.ogness@linutronix.de

Thomas Gleixner (7):
printk: Move buffer size defines
console: Use BIT() macros for @flags values
console: Document struct console
printk: Add struct console_buffers
printk: Use struct console_buffers
printk: Use an output buffer descriptor struct for emit
printk: Handle dropped message smarter

include/linux/console.h | 139 ++++++++++++++++++-----
include/linux/printk.h | 2 -
kernel/printk/printk.c | 240 ++++++++++++++++++++++++++--------------
3 files changed, 269 insertions(+), 112 deletions(-)

base-commit: 11f1e536902b38bffab9913f8908309daf7e53e1
--
2.30.2