From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 1/2] ring-buffer: Fix duplicate results in mapping context to bits in recursive lock
Date: Fri, 19 Jan 2018 12:41:32 -0500 [thread overview]
Message-ID: <20180119174159.986942954@goodmis.org> (raw)
In-Reply-To: 20180119174131.963752801@goodmis.org
[-- Attachment #1: 0001-ring-buffer-Fix-duplicate-results-in-mapping-context.patch --]
[-- Type: text/plain, Size: 1295 bytes --]
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
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>
---
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 0cddf60186da..5af2842dea96 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2579,8 +2579,7 @@ 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;
--
2.13.2
next prev parent reply other threads:[~2018-01-19 17:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-19 17:41 [PATCH 0/2] [GIT PULL] tracing: A couple more small fixes for 4.15 Steven Rostedt
2018-01-19 17:41 ` Steven Rostedt [this message]
2018-01-19 17:41 ` [PATCH 2/2] tracing: Fix converting enums from the map in trace_event_eval_update() Steven Rostedt
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