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printk: Provide helper for message prepending

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In order to support prepending different texts to printk
messages, split out the prepending code into a helper
function.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-11-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
John Ogness 2024-09-04 14:11:29 +02:06 committed by Petr Mladek
parent 13189fa73a
commit 75d430372a
1 changed files with 25 additions and 11 deletions
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36
kernel/printk/printk.c
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@ -2843,30 +2843,31 @@ 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.
* @pmsg is the original printk message.
* @fmt is the printf format of the message which will prepend the existing one.
*
* @dropped is the dropped count to report in the dropped message.
*
* 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.
@ -2888,6 +2889,19 @@ void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
pmsg->outbuf_len += len;
}
/*
* 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).