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ftrace: Clean up the recursion code a bit

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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) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2020-10-30 17:21:00 -04:00
parent 60602cb549
commit 7b68621f8d
1 changed files with 7 additions and 15 deletions
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22
include/linux/trace_recursion.h
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@ -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);
}
/**