Messages in this thread Patch in this message | | | From | Thomas Gleixner <> | Subject | [patch RFC 17/29] printk: Use an output descriptor struct for emit | Date | Sun, 11 Sep 2022 00:27:58 +0200 (CEST) |
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To prepare for a new console infrastructure which is independent of the console BKL wrap the output mode into a descriptor struct so the new infrastrucure can share the emit code which dumps the ringbuffer record into the output text buffers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- include/linux/console.h | 15 +++++++ kernel/printk/printk.c | 94 ++++++++++++++++++++++++++++++++++-------------- 2 files changed, 82 insertions(+), 27 deletions(-)
--- a/include/linux/console.h +++ b/include/linux/console.h @@ -187,6 +187,21 @@ struct cons_text_buf { }; /** + * struct cons_outbuf_desc - console output buffer descriptor + * @txtbuf: Pointer to buffer for storing the text + * @outbuf: Pointer to the position in @buffer for + * writing it out to the device + * @len: Message length + * @extmsg: Select extended format printing + */ +struct cons_outbuf_desc { + struct cons_text_buf *txtbuf; + char *outbuf; + unsigned int len; + bool extmsg; +}; + +/** * struct console - The console descriptor structure * @name: The name of the console driver * @write: Write callback to output messages (Optional) --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2684,40 +2684,39 @@ static void __console_unlock(void) up_console_sem(); } -/* - * Print one record for the given console. The record printed is whatever - * record is the next available record for the given console. - * - * @text is a buffer of size CONSOLE_LOG_MAX. - * - * If extended messages should be printed, @ext_text is a buffer of size - * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL. - * - * If dropped messages should be printed, @dropped_text is a buffer of size - * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL. - * - * @handover will be set to true if a printk waiter has taken over the - * console_lock, in which case the caller is no longer holding the - * console_lock. Otherwise it is set to false. - * - * Returns false if the given console has no next record to print, otherwise - * true. + +/** + * cons_fill_outbuf - Fill the output buffer with the next record + * @con: The console to print on + * @desc: Pointer to the output descriptor + * + * The output descriptor contains all information which is necessary + * to print (buffer pointer, extended format selector...). + * + * Returns: False if there is no pending record in the ringbuffer + * True if there is a pending record in the ringbuffer. + * + * When the return value is true, then the caller has to check + * @desc->outbuf. If not NULL it points to the first character to write to + * the device and @desc->len contains the length of the message. * - * Requires the console_lock. + * If it is NULL then records have been dropped or skipped and con->seq + * has been forwarded so the caller can try to print the next record. */ -static bool console_emit_next_record(struct console *con, struct cons_text_buf *txtbuf, - bool *handover, bool extmsg) +static bool cons_fill_outbuf(struct console *con, struct cons_outbuf_desc *desc) { static int panic_console_dropped; + + struct cons_text_buf *txtbuf = desc->txtbuf; struct printk_info info; struct printk_record r; - unsigned long flags; char *write_text; size_t len; - prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX); + desc->outbuf = NULL; + desc->len = 0; - *handover = false; + prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX); if (!prb_read_valid(prb, con->seq, &r)) return false; @@ -2734,10 +2733,10 @@ static bool console_emit_next_record(str /* Skip record that has level above the console loglevel. */ if (suppress_message_printing(r.info->level)) { con->seq++; - goto skip; + return true; } - if (extmsg) { + if (desc->extmsg) { write_text = txtbuf->ext_text; len = info_print_ext_header(write_text, CONSOLE_EXT_LOG_MAX, r.info); len += msg_print_ext_body(write_text + len, CONSOLE_EXT_LOG_MAX - len, @@ -2747,6 +2746,47 @@ static bool console_emit_next_record(str len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time); } + desc->len = len; + desc->outbuf = write_text; + return true; +} + +/** + * console_emit_next_record - Print one record for the given console + * @con: The console to print on + * @txtbuf: Pointer to the output buffer + * @handover: Pointer to Handover handshake storage + * @extmsg: Selects extended message format + * + * The record printed is whatever record is the next available record for + * the given console. + * + * @handover will be set to true if a printk waiter has taken over the + * console_lock, in which case the caller is no longer holding the + * console_lock. Otherwise it is set to false. + * + * Returns false if the given console has no next record to print, otherwise + * true. + * + * Requires the console_lock. + */ +static bool console_emit_next_record(struct console *con, struct cons_text_buf *txtbuf, + bool *handover, bool extmsg) +{ + struct cons_outbuf_desc desc = { + .txtbuf = txtbuf, + .extmsg = extmsg, + }; + unsigned long flags; + + *handover = false; + + if (!cons_fill_outbuf(con, &desc)) + return false; + + if (!desc.outbuf) + goto skip; + /* * While actively printing out messages, if another printk() * were to occur on another CPU, it may wait for this one to @@ -2761,7 +2801,7 @@ static bool console_emit_next_record(str console_lock_spinning_enable(); stop_critical_timings(); /* don't trace print latency */ - call_console_driver(con, write_text, len, extmsg ? NULL : txtbuf->dropped_text); + call_console_driver(con, desc.outbuf, desc.len, extmsg ? NULL : txtbuf->dropped_text); start_critical_timings(); con->seq++;
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