Commit 7b68621f authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

ftrace: Clean up the recursion code a bit 



In trace_test_and_set_recursion(), current->trace_recursion is placed into a
variable, and that variable should be used for the processing, as there's no
reason to dereference current multiple times.

On trace_clear_recursion(), current->trace_recursion is modified and there's
no reason to copy it over to a variable.

Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 60602cb5

include/linux/trace_recursion.h

+7 −15
Original line number Original line Diff line number Diff line
@@ -162,7 +162,7 @@ extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip); 
static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,

static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,

							int start, int max)

							int start, int max)

{

{

	unsigned int val = current->trace_recursion;

	unsigned int val = READ_ONCE(current->trace_recursion);

	int bit;

	int bit;





	/* A previous recursion check was made */

	/* A previous recursion check was made */
@@ -176,17 +176,14 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign 
		 * a switch between contexts. Allow for a single recursion.

		 * a switch between contexts. Allow for a single recursion.

		 */

		 */

		bit = TRACE_TRANSITION_BIT;

		bit = TRACE_TRANSITION_BIT;

		if (trace_recursion_test(bit)) {

		if (val & (1 << bit)) {

			do_ftrace_record_recursion(ip, pip);

			do_ftrace_record_recursion(ip, pip);

			return -1;

			return -1;

		}

		}

		trace_recursion_set(bit);

	} else {

		barrier();

		return bit + 1;

	}



		/* Normal check passed, clear the transition to allow it again */

		/* Normal check passed, clear the transition to allow it again */

	trace_recursion_clear(TRACE_TRANSITION_BIT);

		val &= ~(1 << TRACE_TRANSITION_BIT);

	}





	val |= 1 << bit;

	val |= 1 << bit;

	current->trace_recursion = val;

	current->trace_recursion = val;
@@ -197,17 +194,12 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign 




static __always_inline void trace_clear_recursion(int bit)

static __always_inline void trace_clear_recursion(int bit)

{

{

	unsigned int val = current->trace_recursion;



	if (!bit)

	if (!bit)

		return;

		return;





	bit--;

	bit = 1 << bit;

	val &= ~bit;



	barrier();

	barrier();

	current->trace_recursion = val;

	bit--;

	trace_recursion_clear(bit);

}

}





/**

/**