linux-kernel - Tracing to console

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Message-ID: <08fe327a686f590008de3d6f43c880c655c648c2.camel@wdc.com>
Date:   Fri, 15 Jun 2018 21:01:53 +0000
From:   Bart Van Assche <Bart.VanAssche@....com>
To:     "rostedt@...dmis.org" <rostedt@...dmis.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mingo@...hat.com" <mingo@...hat.com>
Subject: Tracing to console

Hello Steven,

If I run the following commands as root:

cd /sys/kernel/debug/tracing
grep pm_ available_events > set_event
echo function >current_tracer
grep scsi_ available_filter_functions | while read a b; do echo $a; done >set_ftrace_filter
echo 1 >events/printk/enable
echo 1 >tracing_on
echo 1 >/proc/sys/kernel/tracepoint_printk
echo - - - >/sys/class/scsi_host/host0/scan

then the following appears on the console:

console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
console: console: console: console: console: console: console: console: console: console: console: ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ ... ]

I assume that the repeated "console: " prefix is a bug and also that the same
line repeats over and over again is also a bug? I ran into this with commit
017b3f8a10ca ("scsi: snic: fix a couple of spelling mistakes: "COMPLETE"").

Thanks,

Bart.