From c2702a48b0ebec18337aa5e56139902a8572ee43 Mon Sep 17 00:00:00 2001 From: John Ogness Date: Wed, 9 Dec 2020 01:50:52 +0106 Subject: [PATCH 080/323] printk: inline log_output(),log_store() in vprintk_store() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.215-rt107.tar.xz In preparation for removing logbuf_lock, inline log_output() and log_store() into vprintk_store(). This will simplify dealing with the various code branches and fallbacks that are possible. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20201209004453.17720-2-john.ogness@linutronix.de Signed-off-by: Sebastian Andrzej Siewior --- kernel/printk/printk.c | 145 +++++++++++++++++++---------------------- 1 file changed, 67 insertions(+), 78 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a8af93cbc2936..5af0b0e0259c4 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -493,52 +493,6 @@ static void truncate_msg(u16 *text_len, u16 *trunc_msg_len) *trunc_msg_len = 0; } -/* insert record into the buffer, discard old ones, update heads */ -static int log_store(u32 caller_id, int facility, int level, - enum log_flags flags, u64 ts_nsec, - const struct dev_printk_info *dev_info, - const char *text, u16 text_len) -{ - struct prb_reserved_entry e; - struct printk_record r; - u16 trunc_msg_len = 0; - - prb_rec_init_wr(&r, text_len); - - if (!prb_reserve(&e, prb, &r)) { - /* truncate the message if it is too long for empty buffer */ - truncate_msg(&text_len, &trunc_msg_len); - prb_rec_init_wr(&r, text_len + trunc_msg_len); - /* survive when the log buffer is too small for trunc_msg */ - if (!prb_reserve(&e, prb, &r)) - return 0; - } - - /* fill message */ - memcpy(&r.text_buf[0], text, text_len); - if (trunc_msg_len) - memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); - r.info->text_len = text_len + trunc_msg_len; - r.info->facility = facility; - r.info->level = level & 7; - r.info->flags = flags & 0x1f; - if (ts_nsec > 0) - r.info->ts_nsec = ts_nsec; - else - r.info->ts_nsec = local_clock(); - r.info->caller_id = caller_id; - if (dev_info) - memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info)); - - /* A message without a trailing newline can be continued. */ - if (!(flags & LOG_NEWLINE)) - prb_commit(&e); - else - prb_final_commit(&e); - - return (text_len + trunc_msg_len); -} - int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); static int syslog_action_restricted(int type) @@ -1939,44 +1893,28 @@ static inline u32 printk_caller_id(void) 0x80000000 + raw_smp_processor_id(); } -static size_t log_output(int facility, int level, enum log_flags lflags, - const struct dev_printk_info *dev_info, - char *text, size_t text_len) -{ - const u32 caller_id = printk_caller_id(); - - if (lflags & LOG_CONT) { - struct prb_reserved_entry e; - struct printk_record r; - - prb_rec_init_wr(&r, text_len); - if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) { - 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 */ - return log_store(caller_id, facility, level, lflags, 0, - dev_info, text, text_len); -} - /* Must be called under logbuf_lock. */ int vprintk_store(int facility, int level, const struct dev_printk_info *dev_info, const char *fmt, va_list args) { + const u32 caller_id = printk_caller_id(); static char textbuf[LOG_LINE_MAX]; - char *text = textbuf; - size_t text_len; + struct prb_reserved_entry e; enum log_flags lflags = 0; + struct printk_record r; + u16 trunc_msg_len = 0; + char *text = textbuf; + u16 text_len; + u64 ts_nsec; + + /* + * Since the duration of printk() can vary depending on the message + * and state of the ringbuffer, grab the timestamp now so that it is + * close to the call of printk(). This provides a more deterministic + * timestamp with respect to the caller. + */ + ts_nsec = local_clock(); /* * The printf needs to come first; we need the syslog @@ -2015,7 +1953,58 @@ int vprintk_store(int facility, int level, if (dev_info) lflags |= LOG_NEWLINE; - return log_output(facility, level, lflags, dev_info, text, text_len); + if (lflags & LOG_CONT) { + prb_rec_init_wr(&r, text_len); + if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) { + 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; + } + } + + /* + * Explicitly initialize the record before every prb_reserve() call. + * prb_reserve_in_last() and prb_reserve() purposely invalidate the + * structure when they fail. + */ + prb_rec_init_wr(&r, text_len); + if (!prb_reserve(&e, prb, &r)) { + /* truncate the message if it is too long for empty buffer */ + truncate_msg(&text_len, &trunc_msg_len); + + prb_rec_init_wr(&r, text_len + trunc_msg_len); + if (!prb_reserve(&e, prb, &r)) + return 0; + } + + /* fill message */ + memcpy(&r.text_buf[0], text, text_len); + if (trunc_msg_len) + memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); + r.info->text_len = text_len + trunc_msg_len; + r.info->facility = facility; + r.info->level = level & 7; + r.info->flags = lflags & 0x1f; + r.info->ts_nsec = ts_nsec; + r.info->caller_id = caller_id; + if (dev_info) + memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info)); + + /* A message without a trailing newline can be continued. */ + if (!(lflags & LOG_NEWLINE)) + prb_commit(&e); + else + prb_final_commit(&e); + + return (text_len + trunc_msg_len); } asmlinkage int vprintk_emit(int facility, int level, -- 2.44.0