From: "Steven Rostedt (VMware)" <rost...@goodmis.org>
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: Steven Rostedt (VMware) <rost...@goodmis.org>
---
include/linux/trace_recursion.h | 22 +++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index 228cc56ed66e..a9f9c5714e65 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -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,
int start, int max)
{
- unsigned int val = current->trace_recursion;
+ unsigned int val = READ_ONCE(current->trace_recursion);
int bit;
/* A previous recursion check was made */
@@ -176,18 +176,15 @@ static __always_inline int
trace_test_and_set_recursion(unsigned long ip, unsign
* a switch between contexts. Allow for a single recursion.
*/
bit = TRACE_TRANSITION_BIT;
- if (trace_recursion_test(bit)) {
+ if (val & (1 << bit)) {
do_ftrace_record_recursion(ip, pip);
return -1;
}
- trace_recursion_set(bit);
- barrier();
- return bit + 1;
+ } else {
+ /* Normal check passed, clear the transition to allow it again
*/
+ val &= ~(1 << TRACE_TRANSITION_BIT);
}
- /* Normal check passed, clear the transition to allow it again */
- trace_recursion_clear(TRACE_TRANSITION_BIT);
-
val |= 1 << bit;
current->trace_recursion = val;
barrier();
@@ -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)
{
- unsigned int val = current->trace_recursion;
-
if (!bit)
return;
- bit--;
- bit = 1 << bit;
- val &= ~bit;
-
barrier();
- current->trace_recursion = val;
+ bit--;
+ trace_recursion_clear(bit);
}
/**
--
2.28.0
