| From a80b4e33952be0209ba984df1ff7464a72c353ad Mon Sep 17 00:00:00 2001 |
| From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> |
| Date: Thu, 18 Jan 2018 15:42:09 -0500 |
| Subject: [PATCH 1752/1795] ring-buffer: Fix duplicate results in mapping |
| context to bits in recursive lock |
| |
| 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> |
| Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> |
| --- |
| kernel/trace/ring_buffer.c | 3 +-- |
| 1 file changed, 1 insertion(+), 2 deletions(-) |
| |
| diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c |
| index f04c5b9f1ae9..052b44d616cb 100644 |
| --- a/kernel/trace/ring_buffer.c |
| +++ b/kernel/trace/ring_buffer.c |
| @@ -2592,8 +2592,7 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) |
| 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; |
| -- |
| 2.19.0 |
| |
