diff mbox series

[11/54] ring-buffer: Fix duplicate results in mapping context to bits in recursive lock

Message ID TY1PR01MB16928BA78AE294BD526319E796090@TY1PR01MB1692.jpnprd01.prod.outlook.com (mailing list archive)
State New, archived
Headers show
Series [01/54] tracing: Remove redundant unread variable ret | expand

Commit Message

Motai.Hirotaka@aj.MitsubishiElectric.co.jp Aug. 29, 2018, 12:17 p.m. UTC 
In bringing back the context checks, the code checks first if its normal
(non-interrupt) context, and then for NMI then IRQ then softirq. The final
check is redundant. Since the if branch is only hit if the context is one of
NMI, IRQ, or SOFTIRQ, if it's not NMI or IRQ there's no reason to check if
it is SOFTIRQ. The current code returns the same result even if its not a
SOFTIRQ. Which is confusing.

  pc & SOFTIRQ_OFFSET ? 2 : RB_CTX_SOFTIRQ

Is redundant as RB_CTX_SOFTIRQ *is* 2!

Fixes: a0e3a18f4baf ("ring-buffer: Bring back context level recursive checks")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
(cherry picked from commit 0164e0d7e803af3ee1c63770978c728f8778ad01)
Signed-off-by: Hirotaka MOTAI <Motai.Hirotaka@aj.MitsubishiElectric.co.jp>
---
 kernel/trace/ring_buffer.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 5c4dc1c1..e3769d3c 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2585,18 +2585,17 @@  trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
 	unsigned int val = cpu_buffer->current_context;
 	unsigned long pc = preempt_count();
 	int bit;
 
 	if (!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
 		bit = RB_CTX_NORMAL;
 	else
 		bit = pc & NMI_MASK ? RB_CTX_NMI :
-			pc & HARDIRQ_MASK ? RB_CTX_IRQ :
-			pc & SOFTIRQ_OFFSET ? 2 : RB_CTX_SOFTIRQ;
+			pc & HARDIRQ_MASK ? RB_CTX_IRQ : RB_CTX_SOFTIRQ;
 
 	if (unlikely(val & (1 << bit)))
 		return 1;
 
 	val |= (1 << bit);
 	cpu_buffer->current_context = val;
 
 	return 0;