From: John Ogness Date: Wed, 4 Sep 2024 14:11:29 +0206 Subject: [PATCH 47/54] printk: Provide helper for message prepending Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.11/older/patches-6.11-rt7.tar.xz In order to support prepending different texts to printk messages, split out the prepending code into a helper function. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20240904120536.115780-11-john.ogness@linutronix.de Signed-off-by: Petr Mladek Signed-off-by: Sebastian Andrzej Siewior --- kernel/printk/printk.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2844,30 +2844,31 @@ static void __console_unlock(void) #ifdef CONFIG_PRINTK /* - * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This - * is achieved by shifting the existing message over and inserting the dropped - * message. + * Prepend the message in @pmsg->pbufs->outbuf. This is achieved by shifting + * the existing message over and inserting the scratchbuf message. * - * @pmsg is the printk message to prepend. - * - * @dropped is the dropped count to report in the dropped message. + * @pmsg is the original printk message. + * @fmt is the printf format of the message which will prepend the existing one. * - * If the message text in @pmsg->pbufs->outbuf does not have enough space for - * the dropped message, the message text will be sufficiently truncated. + * If there is not enough space in @pmsg->pbufs->outbuf, the existing + * message text will be sufficiently truncated. * * If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated. */ -void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped) +__printf(2, 3) +static void console_prepend_message(struct printk_message *pmsg, const char *fmt, ...) { struct printk_buffers *pbufs = pmsg->pbufs; const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf); const size_t outbuf_sz = sizeof(pbufs->outbuf); char *scratchbuf = &pbufs->scratchbuf[0]; char *outbuf = &pbufs->outbuf[0]; + va_list args; size_t len; - len = scnprintf(scratchbuf, scratchbuf_sz, - "** %lu printk messages dropped **\n", dropped); + va_start(args, fmt); + len = vscnprintf(scratchbuf, scratchbuf_sz, fmt, args); + va_end(args); /* * Make sure outbuf is sufficiently large before prepending. @@ -2890,6 +2891,19 @@ void console_prepend_dropped(struct prin } /* + * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". + * @pmsg->outbuf_len is updated appropriately. + * + * @pmsg is the printk message to prepend. + * + * @dropped is the dropped count to report in the dropped message. + */ +void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped) +{ + console_prepend_message(pmsg, "** %lu printk messages dropped **\n", dropped); +} + +/* * Read and format the specified record (or a later record if the specified * record is not available). *