Commit 1fb8915b authored Dec 11, 2014 by Steven Rostedt (Red Hat) Committed by Steven Rostedt Dec 11, 2014

printk: Do not disable preemption for accessing printk_func

As printk_func will either be the default function, or a per_cpu function
for the current CPU, there's no reason to disable preemption to access
it from printk. That's because if the printk_func is not the default
then the caller had better disabled preemption as they were the one to
change it.

Link: http://lkml.kernel.org/r/CA+55aFz5-_LKW4JHEBoWinN9_ouNcGRWAF2FUA35u46FRN-Kxw@mail.gmail.com

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent db086554

kernel/printk/printk.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -1859,10 +1859,16 @@ asmlinkage __visible int printk(const char *fmt, ...)
		int r;

		va_start(args, fmt);
		preempt_disable();

		/*
		* If a caller overrides the per_cpu printk_func, then it needs
		* to disable preemption when calling printk(). Otherwise
		* the printk_func should be set to the default. No need to
		* disable preemption here.
		*/
		vprintk_func = this_cpu_read(printk_func);
		r = vprintk_func(fmt, args);
		preempt_enable();

		va_end(args);

		return r;