From f5f022e53b874f978dda23847173cbf2589b07f5 Mon Sep 17 00:00:00 2001 From: John Ogness Date: Mon, 14 Sep 2020 14:39:54 +0206 Subject: [PATCH] printk: reimplement log_cont using record extension Use the record extending feature of the ringbuffer to implement continuous messages. This preserves the existing continuous message behavior. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20200914123354.832-7-john.ogness@linutronix.de --- kernel/printk/printk.c | 98 +++++++++--------------------------------- 1 file changed, 20 insertions(+), 78 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 964b5701688f..9a2e23191576 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -535,7 +535,10 @@ static int log_store(u32 caller_id, int facility, int level, r.info->caller_id = caller_id; /* insert message */ - prb_commit(&e); + if ((flags & LOG_CONT) || !(flags & LOG_NEWLINE)) + prb_commit(&e); + else + prb_final_commit(&e); return (text_len + trunc_msg_len); } @@ -1084,7 +1087,7 @@ static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, dest_r.info->ts_nsec = r->info->ts_nsec; dest_r.info->caller_id = r->info->caller_id; - prb_commit(&e); + prb_final_commit(&e); return prb_record_text_space(&e); } @@ -1884,87 +1887,26 @@ static inline u32 printk_caller_id(void) 0x80000000 + raw_smp_processor_id(); } -/* - * Continuation lines are buffered, and not committed to the record buffer - * until the line is complete, or a race forces it. The line fragments - * though, are printed immediately to the consoles to ensure everything has - * reached the console in case of a kernel crash. - */ -static struct cont { - char buf[LOG_LINE_MAX]; - size_t len; /* length == 0 means unused buffer */ - u32 caller_id; /* printk_caller_id() of first print */ - u64 ts_nsec; /* time of first print */ - u8 level; /* log level of first message */ - u8 facility; /* log facility of first message */ - enum log_flags flags; /* prefix, newline flags */ -} cont; - -static void cont_flush(void) -{ - if (cont.len == 0) - return; - - log_store(cont.caller_id, cont.facility, cont.level, cont.flags, - cont.ts_nsec, NULL, 0, cont.buf, cont.len); - cont.len = 0; -} - -static bool cont_add(u32 caller_id, int facility, int level, - enum log_flags flags, const char *text, size_t len) -{ - /* If the line gets too long, split it up in separate records. */ - if (cont.len + len > sizeof(cont.buf)) { - cont_flush(); - return false; - } - - if (!cont.len) { - cont.facility = facility; - cont.level = level; - cont.caller_id = caller_id; - cont.ts_nsec = local_clock(); - cont.flags = flags; - } - - memcpy(cont.buf + cont.len, text, len); - cont.len += len; - - // The original flags come from the first line, - // but later continuations can add a newline. - if (flags & LOG_NEWLINE) { - cont.flags |= LOG_NEWLINE; - cont_flush(); - } - - return true; -} - static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len) { const u32 caller_id = printk_caller_id(); - /* - * If an earlier line was buffered, and we're a continuation - * write from the same context, try to add it to the buffer. - */ - if (cont.len) { - if (cont.caller_id == caller_id && (lflags & LOG_CONT)) { - if (cont_add(caller_id, facility, level, lflags, text, text_len)) - return text_len; - } - /* Otherwise, make sure it's flushed */ - cont_flush(); - } - - /* Skip empty continuation lines that couldn't be added - they just flush */ - if (!text_len && (lflags & LOG_CONT)) - return 0; - - /* If it doesn't end in a newline, try to buffer the current line */ - if (!(lflags & LOG_NEWLINE)) { - if (cont_add(caller_id, facility, level, lflags, text, text_len)) + if (lflags & LOG_CONT) { + struct prb_reserved_entry e; + struct printk_record r; + + prb_rec_init_wr(&r, text_len, 0); + if (prb_reserve_in_last(&e, prb, &r, caller_id)) { + memcpy(&r.text_buf[r.info->text_len], text, text_len); + r.info->text_len += text_len; + if (lflags & LOG_NEWLINE) { + r.info->flags |= LOG_NEWLINE; + prb_final_commit(&e); + } else { + prb_commit(&e); + } return text_len; + } } /* Store it in the record log */ -- 2.20.1