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ftrace: Clean up the recursion code a bit 

ANBZ: #7841

commit 7b68621f8d upstream.

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>
[dtcccc: Refer to the fix by commit 021b6d11e5 ("tracing: Have all
levels of checks prevent recursion") on stable branch.]
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Reviewed-by: Yuanhe Shu <xiangzao@linux.alibaba.com>
Reviewed-by: Guanjun <guanjun@linux.alibaba.com>
Reviewed-by: Guixin Liu <kanie@linux.alibaba.com>
Link: https://gitee.com/anolis/cloud-kernel/pulls/2570
This commit is contained in:
Steven Rostedt (VMware) 2020-10-30 17:21:00 -04:00 committed by 小龙
parent a8b3465993
commit f97953d560
1 changed files with 3 additions and 8 deletions
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11
include/linux/trace_recursion.h
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@ -145,7 +145,7 @@ 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)
{
unsigned int val = current->trace_recursion;
unsigned int val = READ_ONCE(current->trace_recursion);
int bit;
bit = trace_get_context_bit() + start;
@ -155,7 +155,7 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign
* a switch between contexts. Allow for a single recursion.
*/
bit = start + TRACE_CTX_TRANSITION;
if (trace_recursion_test(bit)) {
if (val & (1 << bit)) {
do_ftrace_record_recursion(ip, pip);
return -1;
}
@ -173,13 +173,8 @@ 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;
bit = 1 << bit;
val &= ~bit;
barrier();
current->trace_recursion = val;
trace_recursion_clear(bit);
}
/**