Re: [PATCH] tracing: Have all levels of checks prevent recursion
From: Alexander Lobakin <aleksander.lobakin@intel.com>
Date: 2023-07-21 15:36:08
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From: Steven Rostedt <rostedt@goodmis.org> Date: Fri, 15 Oct 2021 14:25:41 -0400 Sorry for such a necroposting :z Just wanted to know if this is a bug, so that I could send a fix, or intended behaviour.
quoted hunk ↗ jump to hunk
On Fri, 15 Oct 2021 14:20:33 -0400 Steven Rostedt [off-list ref] wrote:quoted
quoted
I think having one copy of that in a header is better than having 3 copies. But yes, something along them lines.I was just about to ask you about this patch ;-)Except it doesn't build :-p (need to move the inlined function down a bit)diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 4d244e295e85..b32e3dabe28b 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h@@ -77,6 +77,27 @@ /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */ #include <asm/preempt.h> +/** + * interrupt_context_level - return interrupt context level + * + * Returns the current interrupt context level. + * 0 - normal context + * 1 - softirq context + * 2 - hardirq context + * 3 - NMI context + */ +static __always_inline unsigned char interrupt_context_level(void) +{ + unsigned long pc = preempt_count(); + unsigned char level = 0; + + level += !!(pc & (NMI_MASK)); + level += !!(pc & (NMI_MASK | HARDIRQ_MASK)); + level += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
This doesn't take into account that we can switch the context manually via local_bh_disable() / local_irq_save() etc. During the testing of the separate issue[0], I've found that the function returns 1 in both just softirq and softirq under local_irq_save(). Is this intended? Shouldn't that be level += !!(pc & (NMI_MASK)); level += !!(pc * (NMI_MASK | HARDIRQ_MASK)) || irqs_disabled(); level += !!(pc * (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)) || in_atomic(); ? Otherwise, the result it returns is not really "context level".
+ + return level; +} +
[0] https://lore.kernel.org/netdev/b3884ff9-d903-948d-797a-1830a39b1e71@intel.com (local) Thanks, Olek _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv