diff options
| author | John Ogness <john.ogness@linutronix.de> | 2024-08-20 08:35:49 +0206 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2024-08-21 14:56:24 +0200 |
| commit | 70411bf8d22ab3d2f794f199d81d70b62d3a85fa (patch) | |
| tree | d5a65ba6625f1616c88529ed2f7a83cc243882f5 /kernel/printk/printk_safe.c | |
| parent | c158834b223fbfab3a14855ac203b8d9cddbbefd (diff) | |
printk: Add is_printk_legacy_deferred()
If printk has been explicitly deferred or is called from NMI
context, legacy console printing must be deferred to an irq_work
context. Introduce a helper function is_printk_legacy_deferred()
for a CPU to query if it must defer legacy console printing.
In follow-up commits this helper will be needed at other call
sites as well.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240820063001.36405-24-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'kernel/printk/printk_safe.c')
| -rw-r--r-- | kernel/printk/printk_safe.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index 4421ccac31133..86439fd20aabf 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -38,6 +38,15 @@ void __printk_deferred_exit(void) __printk_safe_exit(); } +bool is_printk_legacy_deferred(void) +{ + /* + * The per-CPU variable @printk_context can be read safely in any + * context. CPU migration is always disabled when set. + */ + return (this_cpu_read(printk_context) || in_nmi()); +} + asmlinkage int vprintk(const char *fmt, va_list args) { #ifdef CONFIG_KGDB_KDB @@ -50,7 +59,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) * Use the main logbuf even in NMI. But avoid calling console * drivers that might have their own locks. */ - if (this_cpu_read(printk_context) || in_nmi()) + if (is_printk_legacy_deferred()) return vprintk_deferred(fmt, args); /* No obstacles. */ |