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authorJohn Ogness <john.ogness@linutronix.de>2021-03-03 11:15:26 +0100
committerPetr Mladek <pmladek@suse.com>2021-03-08 11:43:32 +0100
commit996e966640ddea7b535cbe7b749e87a3b24f37e8 (patch)
tree4ff31ecacb0fe11b075edce6c9f24b552c8dff7f /kernel/printk/printk_safe.c
parentf9f3f02db98bbe678a8e57fe9432b196174744a3 (diff)
printk: remove logbuf_lock
Since the ringbuffer is lockless, there is no need for it to be protected by @logbuf_lock. Remove @logbuf_lock. @console_seq, @exclusive_console_stop_seq, @console_dropped are protected by @console_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-14-john.ogness@linutronix.de
Diffstat (limited to 'kernel/printk/printk_safe.c')
-rw-r--r--kernel/printk/printk_safe.c27
1 files changed, 9 insertions, 18 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index 2e9e3ed7d63e..bbf5c1993636 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -16,7 +16,7 @@
#include "internal.h"
/*
- * printk() could not take logbuf_lock in NMI context. Instead,
+ * In NMI and safe mode, printk() avoids taking locks. Instead,
* it uses an alternative implementation that temporary stores
* the strings into a per-CPU buffer. The content of the buffer
* is later flushed into the main ring buffer via IRQ work.
@@ -267,17 +267,9 @@ void printk_safe_flush(void)
void printk_safe_flush_on_panic(void)
{
/*
- * Make sure that we could access the main ring buffer.
+ * Make sure that we could access the safe buffers.
* Do not risk a double release when more CPUs are up.
*/
- if (raw_spin_is_locked(&logbuf_lock)) {
- if (num_online_cpus() > 1)
- return;
-
- debug_locks_off();
- raw_spin_lock_init(&logbuf_lock);
- }
-
if (raw_spin_is_locked(&safe_read_lock)) {
if (num_online_cpus() > 1)
return;
@@ -319,9 +311,7 @@ void noinstr printk_nmi_exit(void)
* reordering.
*
* It has effect only when called in NMI context. Then printk()
- * will try to store the messages into the main logbuf directly
- * and use the per-CPU buffers only as a fallback when the lock
- * is not available.
+ * will store the messages into the main logbuf directly.
*/
void printk_nmi_direct_enter(void)
{
@@ -376,20 +366,21 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
#endif
/*
- * Try to use the main logbuf even in NMI. But avoid calling console
+ * Use the main logbuf even in NMI. But avoid calling console
* drivers that might have their own locks.
*/
- if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK) &&
- raw_spin_trylock(&logbuf_lock)) {
+ if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK)) {
+ unsigned long flags;
int len;
+ printk_safe_enter_irqsave(flags);
len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
- raw_spin_unlock(&logbuf_lock);
+ printk_safe_exit_irqrestore(flags);
defer_console_output();
return len;
}
- /* Use extra buffer in NMI when logbuf_lock is taken or in safe mode. */
+ /* Use extra buffer in NMI. */
if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
return vprintk_nmi(fmt, args);