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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: a0e3a18f4b ("ring-buffer: Bring back context level recursive checks")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
hifive-unleashed-5.1
Steven Rostedt (VMware) 2018-01-18 15:42:09 -05:00
parent 68e76e034b
commit 0164e0d7e8
1 changed files with 1 additions and 2 deletions
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3
kernel/trace/ring_buffer.c
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@ -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;