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printk: Allow printk_trigger_flush() to flush all types

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Currently printk_trigger_flush() only triggers legacy offloaded
flushing, even if that may not be the appropriate method to flush
for currently registered consoles. (The function predates the
NBCON consoles.)

Since commit 6690d6b527 ("printk: Add helper for flush type
logic") there is printk_get_console_flush_type(), which also
considers NBCON consoles and reports all the methods of flushing
appropriate based on the system state and consoles available.

Update printk_trigger_flush() to use
printk_get_console_flush_type() to appropriately flush registered
consoles.

Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/stable/20251113160351.113031-2-john.ogness%40linutronix.de
Tested-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://patch.msgid.link/20251113160351.113031-2-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
John Ogness
2025-11-13 17:09:47 +01:06
committed by Petr Mladek
parent 48e3694ae7
commit d01ff281bd
2 changed files with 23 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/printk/nbcon.c
View File

@@ -1849,7 +1849,7 @@ void nbcon_device_release(struct console *con)
if (console_trylock())
console_unlock();
} else if (ft.legacy_offload) {
printk_trigger_flush();
defer_console_output();
}
}
console_srcu_read_unlock(cookie);

23
kernel/printk/printk.c
View File

@@ -4567,9 +4567,30 @@ void defer_console_output(void)
__wake_up_klogd(PRINTK_PENDING_WAKEUP | PRINTK_PENDING_OUTPUT);
}
/**
* printk_trigger_flush - Attempt to flush printk buffer to consoles.
*
* If possible, flush the printk buffer to all consoles in the caller's
* context. If offloading is available, trigger deferred printing.
*
* This is best effort. Depending on the system state, console states,
* and caller context, no actual flushing may result from this call.
*/
void printk_trigger_flush(void)
{
defer_console_output();
struct console_flush_type ft;
printk_get_console_flush_type(&ft);
if (ft.nbcon_atomic)
nbcon_atomic_flush_pending();
if (ft.nbcon_offload)
nbcon_kthreads_wake();
if (ft.legacy_direct) {
if (console_trylock())
console_unlock();
}
if (ft.legacy_offload)
defer_console_output();
}
int vprintk_deferred(const char *fmt, va_list args)