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-rw-r--r--kernel/printk/printk.c97
1 files changed, 42 insertions, 55 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index c963ba534a78..2523332bd998 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1483,58 +1483,6 @@ static void zap_locks(void)
sema_init(&console_sem, 1);
}
-/*
- * Check if we have any console that is capable of printing while cpu is
- * booting or shutting down. Requires console_sem.
- */
-static int have_callable_console(void)
-{
- struct console *con;
-
- for_each_console(con)
- if (con->flags & CON_ANYTIME)
- return 1;
-
- return 0;
-}
-
-/*
- * Can we actually use the console at this time on this cpu?
- *
- * Console drivers may assume that per-cpu resources have been allocated. So
- * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
- * call them until this CPU is officially up.
- */
-static inline int can_use_console(unsigned int cpu)
-{
- return cpu_online(cpu) || have_callable_console();
-}
-
-/*
- * Try to get console ownership to actually show the kernel
- * messages from a 'printk'. Return true (and with the
- * console_lock held, and 'console_locked' set) if it
- * is successful, false otherwise.
- */
-static int console_trylock_for_printk(void)
-{
- unsigned int cpu = smp_processor_id();
-
- if (!console_trylock())
- return 0;
- /*
- * If we can't use the console, we need to release the console
- * semaphore by hand to avoid flushing the buffer. We need to hold the
- * console semaphore in order to do this test safely.
- */
- if (!can_use_console(cpu)) {
- console_locked = 0;
- up_console_sem();
- return 0;
- }
- return 1;
-}
-
int printk_delay_msec __read_mostly;
static inline void printk_delay(void)
@@ -1681,7 +1629,6 @@ asmlinkage int vprintk_emit(int facility, int level,
boot_delay_msec(level);
printk_delay();
- /* This stops the holder of console_sem just where we want him */
local_irq_save(flags);
this_cpu = smp_processor_id();
@@ -1705,6 +1652,7 @@ asmlinkage int vprintk_emit(int facility, int level,
}
lockdep_off();
+ /* This stops the holder of console_sem just where we want him */
raw_spin_lock(&logbuf_lock);
logbuf_cpu = this_cpu;
@@ -1821,7 +1769,7 @@ asmlinkage int vprintk_emit(int facility, int level,
* semaphore. The release will print out buffers and wake up
* /dev/kmsg and syslog() users.
*/
- if (console_trylock_for_printk())
+ if (console_trylock())
console_unlock();
preempt_enable();
lockdep_on();
@@ -2184,6 +2132,33 @@ int is_console_locked(void)
return console_locked;
}
+/*
+ * Check if we have any console that is capable of printing while cpu is
+ * booting or shutting down. Requires console_sem.
+ */
+static int have_callable_console(void)
+{
+ struct console *con;
+
+ for_each_console(con)
+ if (con->flags & CON_ANYTIME)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Can we actually use the console at this time on this cpu?
+ *
+ * Console drivers may assume that per-cpu resources have been allocated. So
+ * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
+ * call them until this CPU is officially up.
+ */
+static inline int can_use_console(void)
+{
+ return cpu_online(raw_smp_processor_id()) || have_callable_console();
+}
+
static void console_cont_flush(char *text, size_t size)
{
unsigned long flags;
@@ -2254,9 +2229,21 @@ void console_unlock(void)
do_cond_resched = console_may_schedule;
console_may_schedule = 0;
+again:
+ /*
+ * We released the console_sem lock, so we need to recheck if
+ * cpu is online and (if not) is there at least one CON_ANYTIME
+ * console.
+ */
+ if (!can_use_console()) {
+ console_locked = 0;
+ up_console_sem();
+ return;
+ }
+
/* flush buffered message fragment immediately to console */
console_cont_flush(text, sizeof(text));
-again:
+
for (;;) {
struct printk_log *msg;
size_t ext_len = 0;