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-rw-r--r--kernel/printk.c50
1 files changed, 33 insertions, 17 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 19a9556..6b89dd9 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -327,7 +327,9 @@ static void __call_console_drivers(unsigned long start, unsigned long end)
struct console *con;
for (con = console_drivers; con; con = con->next) {
- if ((con->flags & CON_ENABLED) && con->write)
+ if ((con->flags & CON_ENABLED) && con->write &&
+ (cpu_online(smp_processor_id()) ||
+ (con->flags & CON_ANYTIME)))
con->write(con, &LOG_BUF(start), end - start);
}
}
@@ -453,6 +455,18 @@ __attribute__((weak)) unsigned long long printk_clock(void)
return sched_clock();
}
+/* Check if we have any console registered that can be called early in boot. */
+static int have_callable_console(void)
+{
+ struct console *con;
+
+ for (con = console_drivers; con; con = con->next)
+ if (con->flags & CON_ANYTIME)
+ return 1;
+
+ return 0;
+}
+
/**
* printk - print a kernel message
* @fmt: format string
@@ -566,27 +580,29 @@ asmlinkage int vprintk(const char *fmt, va_list args)
log_level_unknown = 1;
}
- if (!cpu_online(smp_processor_id())) {
+ if (!down_trylock(&console_sem)) {
/*
- * Some console drivers may assume that per-cpu resources have
- * been allocated. So don't allow them to be called by this
- * CPU until it is officially up. We shouldn't be calling into
- * random console drivers on a CPU which doesn't exist yet..
+ * We own the drivers. We can drop the spinlock and
+ * let release_console_sem() print the text, maybe ...
*/
+ console_locked = 1;
printk_cpu = UINT_MAX;
spin_unlock_irqrestore(&logbuf_lock, flags);
- goto out;
- }
- if (!down_trylock(&console_sem)) {
- console_locked = 1;
+
/*
- * We own the drivers. We can drop the spinlock and let
- * release_console_sem() print the text
+ * 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.
*/
- printk_cpu = UINT_MAX;
- spin_unlock_irqrestore(&logbuf_lock, flags);
- console_may_schedule = 0;
- release_console_sem();
+ if (cpu_online(smp_processor_id()) || have_callable_console()) {
+ console_may_schedule = 0;
+ release_console_sem();
+ } else {
+ /* Release by hand to avoid flushing the buffer. */
+ console_locked = 0;
+ up(&console_sem);
+ }
} else {
/*
* Someone else owns the drivers. We drop the spinlock, which
@@ -596,7 +612,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
printk_cpu = UINT_MAX;
spin_unlock_irqrestore(&logbuf_lock, flags);
}
-out:
+
preempt_enable();
return printed_len;
}
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